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Article

Time-Delayed Cold Gelation of Low-Ester Pectin and Gluten with CaCO3 to Facilitate Manufacture of Raw-Fermented Vegan Sausage Analogs

by
Maurice Koenig
1,
Kai Ahlborn
1,
Kurt Herrmann
1,
Myriam Loeffler
2 and
Jochen Weiss
1,*
1
Department of Food Material Science, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstraße 25, 70599 Stuttgart, Germany
2
Department of Microbial and Molecular Systems, Meat Technology & Science of Protein-Rich Foods (MTSP), Leuven Food Science and Nutrition Research Centre, KU Leuven Campus Ghent, Gebroeders de Smetstraat 1, 9000 Ghent, Belgium
*
Author to whom correspondence should be addressed.
Appl. Sci. 2025, 15(15), 8510; https://doi.org/10.3390/app15158510
Submission received: 23 June 2025 / Revised: 18 July 2025 / Accepted: 25 July 2025 / Published: 31 July 2025
(This article belongs to the Special Issue Processing and Application of Functional Food Ingredients)
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Abstract

To advance the development of protein-rich plant-based foods, a novel binder system for vegan sausage alternatives without the requirement of heat application was investigated. This enables long-term ripening of plant-based analogs similar to traditional fermented meat or dairy products, allowing for refined flavor and texture development. This was achieved by using a poorly water-soluble calcium source (calcium carbonate) to introduce calcium ions into a low-ester pectin—gluten matrix susceptible to crosslinking via divalent ions. The gelling reaction of pectin–gluten dispersions with Ca2+ ions was time-delayed due to the gradual production of lactic acid during fermentation. Firm, sliceable matrices were formed, in which particulate substances such as texturized proteins and solid vegetable fat could be integrated, hence forming an unheated raw-fermented plant-based salami-type sausage model matrix which remained safe for consumption over 21 days of ripening. Gluten as well as pectin had a significant influence on the functional properties of the matrices, especially water holding capacity (increasing with higher pectin or gluten content), hardness (increasing with higher pectin or gluten content), tensile strength (increasing with higher pectin or gluten content) and cohesiveness (decreasing with higher pectin or gluten content). A combination of three simultaneously occurring effects was observed, modulating the properties of the matrices, namely, (a) an increase in gel strength due to increased pectin concentration forming more brittle gels, (b) an increase in gel strength with increasing gluten content forming more elastic gels and (c) interactions of low-ester pectin with the gluten network, with pectin addition causing increased aggregation of gluten, leading to strengthened networks.

1. Introduction

Global food production is striving to become more material-, labor- and energy-efficient. Hence, research is focusing on the design and production of consumer-acceptable plant-based foods, which have been shown to require fewer natural resources and to be less taxing on the environment [1,2]. Increasing the amount of plant-based foods globally is not an easy task, though, since meat often serves as the main protein source in many diets. Nutritional value, texture, taste and cultural practices pose substantial hurdles to shifting diets towards a predominately plant-based one [3,4]. To increase the approval of plant-based foods, protein-rich plant-based meat analogs (PBMAs) with organoleptic properties similar to those of their animal counterparts have been researched and developed, with a variety of products now being available in supermarkets. PBMAs that imitate processed meat products such as sausages are especially popular [5] and typically consist of insoluble textured plant proteins bound together via a first sticky, later solidifying binding system [6,7]. These binders usually require a heating step for solidification, and examples thereof include plant proteins heated to 65–85 °C to induce denaturation and crosslinking [8], modified starches heated to 52–100 °C to induce gelation [9], and hydrocolloids such as agar-agar, locust bean gum and xanthan heated to 50–90 °C to promote chain interactions and network formation [10]. While enzymes such as transglutaminase do not require heating to create crosslinks, a thermal treatment at 65–85 °C is typically needed to render them inactive in the final product.
However, creating PBMAs with appealing quality attributes remains a challenge [11,12], and often a large number of additives (e.g., flavoring and preserving agents, stabilizers, and antioxidants) are required in their manufacture, which is detrimental to consumer acceptance [13]. Improvements could come from using novel processing approaches [12], amongst which microbial fermentation has been shown to be particularly promising, especially if specialized starter cultures are used. Implementation of fermentation therefore has the potential to replace many of these additives, since many fermentatively formed substances can take on tasks that are currently still performed by additives. For instance, fermentation has been shown to be able to improve the shelf life and quality of PBMAs [14,15,16], allowing for a reduction in preservatives and stabilizers; fermentation of pea protein with lactic acid bacteria also decreased the extent of protein oxidation [17], enabling a reduction in antioxidant insertion. The same also applies to the fermentative reduction of unwanted structures in products, like the reduction and masking of undesired flavor compounds inherent in many plant proteins [18,19], which in turn ensures the usage of fewer flavorings to mask off-flavors in these products.
Moreover, fermentation may not only reduce the amount of undesirable flavor compounds in PBMAs, but also lead to the generation of new, desirable compounds. In dry fermented meat sausages, over 80 aroma active compounds were identified, most of them derived from the conversion of spices (60.5%), lipid oxidation (18.9%) and amino acid catabolism (11.8%) during ripening [20]. Similarly, the fermentation of some cereals has been shown to produce volatile compounds not unlike those found in fermented meat products [18]. Initial studies on the fermentation of protein extrudates made by high-moisture extrusion cooking have also demonstrated that suitable starter cultures, like those used in the production of dry fermented meat sausages, cleave plant proteins to produce bioactive peptides and amino acids and generate lactic acid without incurring negative effects on texture attributes like springiness and cohesiveness [21].
Both the production of desired meaty aromas and the degradation of undesired aromas during fermentation of plant substances have already been demonstrated several times; however, commercially successful products depend not only on individual aroma substances but also on well-adjusted overall aroma profiles. These can only be achieved by targeted combinations of specialized starter cultures with corresponding substrates under optimized fermentation conditions [22,23]. Large-scale screenings of various plant materials with suitable fermentative strains will be required for quality development, as it is tremendously difficult to predict the effects combined substrates and cultures can have on each other and on products [24].
However, the implementation of fermentative strains in PBMA production proves to be difficult, since the heat-inactivation of the desired strains is inevitable when thermal treatments, which are required for proper texture development, are applied. By omitting these thermal treatments, most common binding materials used in PBMAs on the market are unusable. Furthermore, the survival of undesired spoilage and pathogenic strains, usually desirably inactivated during thermal treatment, poses another difficulty. However, if ‘raw fermented’ products are to be manufactured, where flavor and texture modifications occur over long time spans due to the metabolic activity of microorganisms, thermal treatment has to be avoided.
In theory, starter cultures could also be added to products after a heating step, e.g., by injection or surface treatment. The latter provides the simplest method, and products with small volumes can benefit from it especially. It can be carried out after the classic production and heating of a product and hardly changes anything in the usual production processes. Only the subsequent novel maturing processes needs to be explored. For larger product volumes, however, simple surface treatments are not sufficient to provide the inside of the matrix with sufficient starter cultures, since the penetration depth of most starter cultures (except deeply penetrating mold mycelia [25]) is very limited (<5 mm [26]). In this case, these would have to be introduced by injection under the most sterile conditions possible, which would require the purchase of new equipment for many PBMA producers and would therefore not be financially viable. For these products of larger volume, it would thus be preferable to use cold-set binding systems, since these mimic the approach used in the production of traditional fermented meat and dairy products, such as raw fermented sausages and raw milk cheeses [27]. In this process, meat and dairy proteins form networks due to attractive molecular interactions promoted by low pH levels and the presence of salt. The gelation of these traditional cold-setting systems does not occur immediately but rather over a period of time, thereby facilitating operations such as filling and shaping prior to ripening. Thus, plant-based cold-set binder systems must exhibit a slow gelation kinetic in order to be fit for purpose.
Cold-set binders are defined as binders that can gel without the need of heating to induce texture formation. The most commonly used cold-set gels are formed by acid-, ion- and enzyme-induced crosslinking [28,29]. It is known that some proteins such as soy protein isolates can form cold-set gels after the addition of cations such as calcium or iron when denatured first via heating [30,31]. However, the resulting gels based on plant proteins to date lack sufficient texture and cohesion. This can be improved using transglutaminase (TG), an enzyme that catalyzes the formation of isopeptide bonds between proteins [32] and hence improves network formation between proteins. However, as mentioned above, the use of TG usually is typically accompanied by a heating step to inactivate the enzyme due to issues surrounding labeling, safety and quality [13,33]. Thus, there is a need to carry out research in the development of cold-set plant protein gels with firmer structures facilitating slicing or shredding.
Wheat gluten is a widely used plant protein in the manufacture of PBMAs [34]. It can be found as a structuring ingredient in traditional products such as seitan, but also in textured vegetable protein (TVP) [35,36], and in complex PBMAs [37]. Vital wheat gluten is a cohesive, viscoelastic complex of proteins characterized by a high viscoelasticity when hydrated [38] and is able to form extensible continuous networks that are strong yet adhesive [39]. When used as an ingredient in complex PBMAs, wheat gluten has been reported to modulate structural as well as sensory properties [40]. Gluten networks are also known to interact with other components in PBMAs such as starch and hydrocolloids [41,42]. Further research regarding the design of complex binder systems with wheat gluten and other binding agents in model systems has been recommended [37].
Among cold-gelling hydrocolloids, the most used ones are alginate, carrageenan and pectin. These long-chained polysaccharides found in the cell walls of brown algae (alginate), red seaweed (carrageenan), and citrus fruits and apples (pectin) are crosslinkable by multivalent ions and can form elastic-to-rigid gel structures depending on their origin, molecular structure and environmental conditions [43]. Pectin has a high acceptance amongst consumers and is composed of glycosidic α-1.4-linked D-galacturonic acid chains [44]. Depending on the degree of esterification (DE) of the carboxyl group of the galacturonic acid, pectins are classified as either high-ester pectin (DE > 50%; high-methoxyl pectin) or low-ester pectin (DE > 50%; low-methoxyl (LM) pectin) [43]. Amidated pectins (or amidated low-methoxyl pectins) are readily available and are obtained by de-esterification using ammonia, resulting in the substitution of the methyl ester groups with amid groups. High-ester pectin gels may be formed with various sugars, typically at concentrations above 55% at low pH values (pH < 3.5), while low-ester and amidated low-ester pectins gel with divalent cations [44], of which the most prevalent in the food industry is calcium due to its low toxicity and price [45]. Gelation in these systems is rapid and occurs quickly after mixing with the hydrocolloid, making subsequent mixing and filling operations difficult.
To make fermentation in PBMA products like raw fermented sausages possible, we propose the usage of a low-water-soluble calcium source such as calcium carbonate (calcite: 0.00066 g/100 mL) [46] to introduce calcium ions into the hydrocolloid matrix without instant gelation reaction, as it was proposed for homogeneous alginate gels as a cultivation medium for microbiology usage [47]. Upon contact with lactic acid, calcium carbonate is known to react to water-soluble calcium lactate (4.8 g/100 mL) [48,49] and hence should initiate time-delayed calcium gelation upon contact with lactic acid, formed during fermentation with lactic acid bacteria (LAB). This yields a cold-gelling hydrocolloid matrix stabilizing around a wheat gluten basic structure. Hence, applied in combination, it should resemble the gelation process of a model product ‘raw-fermented sausage’ and allow for raw-fermented vegan sausage analogs to be manufactured. The process has the potential to offer all the advantages of classic raw-fermented products, namely, influencing flavor, texture, bioavailability and shelf life. This study aims to investigate the feasibility and practical applicability of generating such a matrix, identify the influence of matrix compositions, as well as assess the proposed model matrix in terms of its suitability as a meat substitute.

2. Materials and Methods

2.1. Materials

For the manufacture of a plant-based salami-type sausage model that could be used for investigations into time-delayed cold gelation, a complex matrix was produced. Wheat gluten texturate (TVP; product name: SCM110; 65.0% protein, 19.5% carbohydrate, 7.6% ash, 3.4% fat, 4.5% water) produced via low-moisture extrusion cooking was obtained from Loryma GmbH (Zwingenberg, Germany), and a plant-based solid-fat replacer (70% fat, 27.1% water, 2.7% protein, 0.1% carbohydrate, 0.1% ash) based on a crosslinked emulsion gel [50] was produced to mimic animal fat. Further, gluten powder (vital wheat gluten 838001; Loryma GmbH, Zwingenberg), amidated low-ester pectin (Amid CF025; 24–29% DE, 21–25% DA; Herbstreith & Fox GmbH & Co. KG, Neuenbürg, Germany), calcium carbonate (Salandis GbR, Greifswald, Germany) and spices were used. Beetroot powder, garlic paste (420300014DE) and monosodium glutamate were used as additives and obtained from Van Hees GmbH (Walluf, Germany). Sweet paprika powder and salt (NaCL) were purchased from MEGA (Das Fach-Zentrum für die Metzgerei und Gastronomie eG, Stuttgart, Germany). Black pepper was purchased from Fuchs Foodservice GmbH (Dissen a.T.W., Germany). Salami aroma ‘salami pulvermischung’ was obtained from Givaudan SA (Vernier, Switzerland). Iron oxide (Eisenoxid) was purchased from Jack Link’s LSI (Ansbach, Germany). The batter was inoculated with a commercial raw-fermented sausage starter culture, ‘Bitec LK30’, with 0.25 g/Kg, according to the manufacturer’s instructions (Frutarom Savory Solutions Austria GmbH, Salzburg, Austria), and consisted of lactobacilli, staphylococci and micrococci.

2.2. Sausage Manufacturing

Six batches of 4 kg each of a plant-based sausage mix were produced using standard meat processing equipment on a pilot plant scale, according to Figure 1, using the formulation shown in Table 1. The preparation was based on established principles published previously [51], and the chosen ingredients were carefully selected in consultation with the respective manufacturers as well as unpublished preliminary trials, some of which can be viewed in the Supplementary Materials.
First, the pectin solutions were prepared in a kitchen appliance (TM6 Thermomix; Vorwerk Deutschland Stiftung & Co. KG, Wuppertal, Germany) in which pectin (40 g, 120 g, 200 g) was dissolved in 90 °C distilled water (2120 g, 2040 g, 1960 g) for 3 min at level 3 (500 rpm), followed by 3 min at level 6 (3100 rpm). According to the manufacturer, high-shear stirring at high temperatures for a short time enables the pectin to dissolve completely, even at higher concentrations, while keeping pectin hydrolysis at a minimum. Afterwards the honey-like dispersion was allowed to cool down to about 45 °C. A chilled solid-fat replacer emulsion gel was chopped into cubes of 12 mm size using a dice cutter (Type 0802; Marel TREIF GmbH, Oberlahr, Germany). For the main production, soaked TVP was mixed with one half of the gluten powder in a bowl chopper (K64 AC8 VAK; Seydelmann KG, Aalen, Germany) for 30 s at 1000 rpm with backwards-spinning knives (i.e., the mixing mode). Then, the mixture was comminuted for 30 s at 1500 rpm. Spices (Table A1), CaCO3 and the starter culture (0.25 g/kg) were mixed in for 90 s using the mixing mode. Then, the emulsion gel cubes and the second half of the gluten powder were added and further comminuted for 30 s at 1500 rpm, yielding a loose, particulate mass. Finally, the pectin solution was added and mixed in for 90 s using a mixing mode which caused the loose particles to stick together to form a coherent mass. The plant-based ‘sausage analog batter’ was then filled into cellulose casings (49 mm diameter; NOJAX E-Z PEEL; Viskase, Lombard, IL, USA) using a vacuum filler (VF 610 plus; Albert Handtmann Holding GmbH & Co. KG, Biberach, Germany), yielding 4 sausages of 900 g each. These were subsequently cold-smoked (25 °C, 75% RH, 2 × 7 min after 24 h and 48 h), fermented and dried simultaneously in a cooking and smoking chamber (Airmaster UK 1800 BE, FR 702; Reich Thermoprozesstechnik GmbH, Schechingen, Germany).
The structure of the final sausage matrix is schematically shown in Figure 2.

2.3. Fermentation

The sausages were ripened at 25 °C for the first 24 h to ensure starter culture growth and subsequently dried at 15 °C (air circulation velocity: 600 m3/h) in 24 h steps, with the relative humidity (RH) decreasing by 2% every 24 h, starting at 96% and finishing at 80% RH after 8 days. The sausages were treated with friction smoke for 15 min after 24 h, 48 h and 72 h of drying to prevent mold growth on surfaces and to give the matrix a product-typical smoky aroma, surface structure and coloring. Samples with a dry matter content of 55% or 65% were taken from the chamber, packed under vacuum conditions (C 400, MULTIVAC; Sepp Haggenmüller SE & Co. KG, Wolfertschweden, Germany) and stored at 15 °C for further ripening until analysis. Fermentation, drying and ripening temperatures were selected based on processing of the meat-containing original product, allowing the growth of desired starter strains early on in the process, yet subsequently slowing down the growth of pathogens [52]. Taking the drying period into account, the matrices were thus ripened for 21 days after production and remained unheated throughout the whole process.

2.4. Assessment of Time-Delayed Gelation

To assess the delay in the gelation reaction time and hence the practicability of the proposed methodology, samples of the plant-based ‘sausage analog batter’ containing 15% gluten–3% pectin were additionally filled into sealable 30 mL cups after varying storage times at 15 °C between final mixing and filling (0 min, 30 min, 60 min, 120 min). Additionally, a batch of the same mass was produced without the addition of a starter culture to evaluate the effects of microbial acidification on the texture. Once filled, the cups were ripened sealed for 24 h at 25 °C, followed by 72 h at 15 °C. Subsequently, texture analysis (n = 8) was performed using a 15 mm diameter flat cylinder with a puncture depth of 15 mm via a texture analyzer (Instron Model 3365 Tensile Tester; Instron GmbH, Darmstadt, Germany).

2.5. Physicochemical Properties

All physicochemical properties were determined in triplicate if not stated otherwise. The pH value of the sausages was measured with a pH meter (pH 537, WTW; Weilheim, Germany). aw values of the raw batter as well as of the sausages with 55% and 65% dry matter contents were determined using a HygroPalm water activity meter (AW1, Rotronic AG; Bassersdorf, Switzerland). Total fat content was measured in duplicate after acid hydrolysis of homogenized samples according to the Weibull–Stold method, followed by Soxhlet extraction (B-811; Büchi Labortechnik AG, Flawil, Switzerland), using petroleum ether as a solvent [53]. The protein content was measured via the Dumas combustion method using an automatic nitrogen analyzer (C. Gerhardt GmbH & Co. KG, Königswinter, Germany) and calculated from the nitrogen content using a protein conversion factor for wheat gluten of 5.61 [54]. Ash content was determined by preheating the samples for 24 h at 200 °C, with subsequent incineration for 48 h at 600 °C in a muffle furnace (Type M 110; Heraeus Instruments GmbH, Bad Grund, Germany).

2.6. Texture Analysis

Texture analysis of the sausages was performed using a texture analyzer using cylindrical specimens of 15 mm diameter and height that had been cut from the matrix core to minimize the influence of dry edges. The samples were uniaxially compressed twice between two plate geometries with a matrix compression of 75% for (a) hardness measurement (n = 10) and a matrix compression of 50% for (b) springiness and (c) cohesiveness (n = 10) measurement, as recommended for meat product analysis [55]. Additionally, the tensile strength (d); (n = 12) was measured via a rupture test, analyzing the force required to pull apart sample cylinders of 34 mm diameter (=9.08 cm2) and 7 mm height which had been glued between the two plate geometries, adapted after Herz [56].

2.7. Food Safety

Three of the sausage samples containing 15% gluten and 1%, 3% and 5% pectin were analyzed representatively for their food safety after 21 days of ripening at 15 °C by a commercial laboratory for food hygiene (Institut für Lebensmittelhygiene Rüdiger Stroh, Dreifelderstr. 4, 70599 Stuttgart) following § 64 LFGB and DIN ISO-Methods. They were tested for aerobic mesophilic colony-forming units (cfu), referred to in the following as the ‘fermentation flora’, and common food pathogens, including Escherichia coli, Listeria monocytogenes and Salmonella spp. Details of the analysis can be found in Figure A1 and Figure A2 of Appendix B.

2.8. Sensorial Analysis

There was not sufficient sample material to include a full sensorial analysis; therefore, only a minor internal tasting of selected remaining samples was carried out. Samples were cut in 1 mm thick slices (cold cuts) and descriptively analyzed by trained panelists (n = 5 people).

2.9. Statistical Analysis

Statistical analysis was performed using the SPSS Statistics 27 program (IBM Deutschland GmbH, Ehningen, Germany). After a Levene test revealed the heterogeneity of variances, Welch tests were performed to compare single attributes. Differences of p < 0.05 were considered to be significantly different. Despite the heterogeneity of variances, 2-way analysis of variance (ANOVA) was additionally performed.

3. Results and Discussion

3.1. Assessment of Time-Delayed Gelation

The functionality of the proposed method in terms of gelling and the time by which it was delayed was assessed. In industrial production dimensions, delays in production processes can always occur and can lead to longer downtimes at various points in the process. It is therefore advantageous if a product can bridge longer periods of time before final completion without any loss of quality.
The gelling reaction itself happened as anticipated; the introduced CaCO3 was able to react effectively with the low-ester pectin and formed firm gels. The time delay of this reaction was also possible, however, due to the low intrinsic pH of the pectin solution (pH = 4.2); a partial gelling reaction of low-ester pectin with calcium occurred gradually over time before the fermentation started. This is to be seen in Figure 3, in which a clear drop in hardness can be observed with longer storage times before filling in both the fermented and unfermented matrix. This indicates that, especially in the first 60 min after mixing, a partial gelling reaction between pectin and CaCO3 occurred, even without microbial acid being involved. These early-gelled structures were again disrupted by the high shear forces during the filling process, which is why they could no longer contribute to the structure of the final matrix with similar efficiency to the pectin that gelled in the final position after filling.
A certain gel strength was also achieved without implementation of fermentation; however, the fermented matrices (pH = 4.6) exhibited a distinctly better-developed gel structure across all samples compared to the non-fermented ones (pH = 5.7).
In order to create matrices that are as firm as possible, the storage time between mixing and filling should be kept as short as possible, which is not optimal for manufacturing. However, this only applies to the mixing of low-ester pectin and CaCO3, which enables slightly extended flexibility in production. Of course, this is not an exclusion criterion for products; liver sausage, for example, must be filled and further processed directly after creating the emulsion in order to prevent the final product quality from deteriorating [57]. However, it would be advantageous to extend these potential intermediate storage times without affecting the product. An important factor that influences the dissociation speed of calcium ions into the surrounding environment is the particle size of the used CaCO3. Finer grinds lead to larger contact areas and hence faster gelling [47]. Alternatively, another hydrocolloid with less internal acidity, such as ι-carrageenan (pH = 8–11) [58], could be used. Another option would be to encapsulate or bind the calcium by complexing, as is already performed in other applications. EDTA (E 385), for example, would be an option here, which also is known to release calcium at pH values lower than pH = 4.0 [59]. This in turn would be too late a release, which would disrupt the organoleptic properties of the product due to the low pH value. Further research in this area would be necessary to optimize the process. Assuming it can be ensured that filling can happen fairly directly after mixing, the proposed method can be successfully applied.

3.2. Physicochemical Properties

3.2.1. Weight Loss

Due to the varying batch compositions, the initial dry matter content also varied (see Table 1). In previous experiments with similar matrices, the dry matter content had proven to be decisive, especially for textural properties [60]. The sausages were hence dried and ripened after production until equal dry matter contents of 55% and 65% for each batch were reached. The dry matter of traditional raw-fermented sausages usually ranges between 55 and 85% [61,62,63], whereas plant-based salami analogs usually have between 29 and 64% dry matter [64]. The weight loss development for all batches during the first 8 days of drying is shown in Figure 4.
The drying kinetics were primarily influenced by the pectin concentration and only slightly by the total water content. Samples with 1% pectin lost weight the fastest, followed by samples containing 3% and 5% pectin. Samples containing only 10% gluten also consistently lost weight faster than their 15%-gluten counterparts. According to Herz, Moll, Schmitt and Weiss [37], water binding can be considered a key attribute to evaluate binder functionality, along with stickiness and hardness. Hence, pectin addition increased binder functionality in this regard distinctly. Low-ester pectin is known to enhance the structure of gluten networks through increased intermolecular hydrogen bonds as well as the conversion of sulfhydryl groups (-SH) to disulfide bonds (-S-S-), which increases the water holding capacity of gluten protein matrices [41,42]. Additionally, formation of random coils can occur, leading to competition for water between gluten proteins and polysaccharides, resulting in further structural changes depending on available water [65]. Additional visual representations of the raw-fermented sausage analog cross sections are shown in Figure 5.

3.2.2. pH Value

The final pH values of all samples (pH 4.3–4.5) were below the range reported for traditional meat-based salamis, which tends to be pH 4.8–5.5 [66,67]. Similar to the drying kinetics, pH development was primarily influenced by pectin concentration and only slightly by water content. Higher pectin concentrations led to lower pH values, probably caused by the pectin’s native pH when dissolved in water (pH 4.2 ± 0.5). The dextrose content might also have had an influence, since pectin is standardized with it by the manufacturer. The latter provides a more readily available substrate for lactic acid fermentation, potentially contributing to a lower pH. Additionally, an increased gluten content led to slightly higher pH values. This could have been caused by the lower aw value associated with gluten addition in these batches and thus decreased metabolic activity of the microorganisms, combined with a different buffering capacity of gluten. Glutamic acid makes up a large part of gluten (~37%) [68], and with its pKa2 at pH 4.25 [69], where the strongest buffering effect of the amino acid can be expected, the total buffering capacity of gluten in this pH range can also be expected to make a contribution.

3.2.3. aw Value

The water activity in the raw batter after production ranged from 0.971 to 0.966, as shown in Table 2. With decreasing aw values at higher gluten and pectin concentrations, this was in line with the initial dry matter content the samples had. Similar trends in pH and weight loss developments were apparent once the samples were dried to 55% and 65%, with both of the binder components providing water binding capacity. Synergistic effects between the components were observed, since low-ester pectin is known to increase the water holding capacity of gluten protein matrices [41,42]. At 65% dry matter, the aw values ranged from 0.926 to 0.916, which is somewhat higher than in dried salami, which typically have aw values of around 0.90–0.88 in order to be shelf-stable at room temperature [52]. Water activity, however, has been found to be closely related to the juiciness of the product (see ‘Sensory Analysis’), which is why further drying of the product would have a downside until a better fat substitute is found which can compensate the increased drying.

3.2.4. Chemical Constituents

The results of the chemical analysis are shown in Table 3. The protein content in the raw batter after production ranged from 14.89% to 19.39%, in accordance with the composition of the matrix; and samples with 15% gluten in the raw batter showed an approximately 5% higher protein content compared to samples with 10% gluten. Similar trends were visible for total water content (increasing with lower gluten and pectin concentrations) and carbohydrate content (increasing with higher pectin concentrations). Carbohydrate contents ranged from 6.43% to 11.25%, and thus were considerably higher than values found in traditional meat salami batter, where carbohydrate content is modulated with dextrose addition (0.25–1%) [62]. Fat and ash contents were consistent throughout the batches at about 10% and 2.7%, respectively.

3.3. Texture Analysis

The results of the texture profile analysis are depicted in Figure 6. Due to software issues during the measurement, the TPA data for batch ‘15% gluten–1% pectin–55% dry matter’ was lost and there was not sufficient sample material left to repeat the measurement in statistically relevant repetition numbers. Hence, it was not included in the assessment.

3.3.1. Pectin Concentration

With increasing pectin content (statistical reference letter: a-b-c), the hardness increased as well. In samples with higher gluten contents, however, the relative influence of pectin was reduced, yet it was still visible and significant. The same trend appeared for tensile strength as well as springiness. Cohesiveness, on the other hand, decreased with increasing pectin concentration, hinting towards a less elastic matrix.
This can be attributed to a combination of three simultaneously occurring effects, namely, (a) an increase in gel strength due to the low-ester pectin–calcium gel due to increased pectin concentration, (b) interactions of low-ester pectin with the gluten network and (c) the slightly higher binder-to-extrudate ratio. Calcium-induced gels with low-ester pectins are known to form stronger yet more brittle gels with increasing pectin concentrations [70,71], which is in line with these findings.
Furthermore, several studies report that low-ester pectin interacts with gluten networks when applied in combination, with higher pectin contents also leading to increased pectin–gluten interactions [42], where network formation develops progressively over time, promoting stronger dough structures [72]. The hardness and elasticity of gluten networks can be attributed to the formation of disulfide and hydrogen bonds [73], with pectin addition causing increased aggregation of gluten through intermolecular hydrogen bonds [42], conversion of sulfhydryl groups (-SH) to disulfide bonds (-S-S-) [41], electrostatic interaction [74] or the formation of random coils [65], all of which contribute to strengthened gluten networks, though they do not necessarily influence the cohesiveness [75]. Hence, we concluded that the observed reduced cohesiveness could predominantly be caused by the calcium-induced pectin gel, whereas increased hardness and tensile strength may be caused by both effects. In the studied system, the overall texture is influenced by both components, the gluten as well as the pectin networks, as well as interactions between the two.

3.3.2. Gluten Concentration

With a higher gluten content within the sausage matrix (statistical reference letter: X-Y), an increase in hardness and a decrease in cohesiveness were found, again consistent with a higher binder-to-extrudate ratio, leading to stronger yet less elastic matrices. There was, however, no significant influence of gluten on springiness or tensile strength. It should be further mentioned that in complex composite systems each of the individual structural units contributes to the behavior of the overall system, and since the individual components all have different mechanical properties, a non-linear mixing behavior can result with increasing binder content and decreasing fiber extrudate content [60].

3.3.3. Dry Matter

With increasing dry matter content (statistical reference letter: K-L), hardness and tensile strength were increased. However, there was no influence found on springiness. Cohesiveness was reduced with increased dry matter at lower gluten contents (10%), while there was no statistical difference at 15% gluten content. Additionally, two-way ANOVA revealed that only at higher dry matter contents were significant differences found for the combinatorial effect of pectin and gluten.
In summary, the increase in dry matter, gluten and pectin contents led to an increased hardness and a decreased cohesiveness. For springiness and tensile strength, there were trends visible towards increased springiness, with higher pectin concentrations as well as higher tensile strength due to increased pectin and dry matter contents.

3.3.4. Practical Assessment

Since the transferability of these findings to actual mouthfeel and chewing experience is limited, these TPA values were put in perspective by comparison with TPA values typically found for traditional dry fermented sausages based on a broad case study with similar analysis settings [61]. To this end, all values were adjusted to standardized values (N/cm2) to ensure comparability. Hardness values of traditional samples ranged from 31.26 N/cm2 to 87.89 N/cm2, with an average value of 41.87 N/cm2, compared to our plant-based matrices with values of 6.85 N/cm2–79.34 N/cm2. The springiness results of traditional samples were in the range of 4 mm–6.7 mm, averaging 4.7 mm, whereas the plant-based matrices produced here ranged from 3.7 to 5.4 mm. The obtained cohesiveness values ranged from 0.32 to 0.45 for meat salamis, averaging 0.40, whereas the plant-based matrices ranged from 0.29 to 0.40. Finally, the tensile strength ranged from 0.7 N/cm2 to 20.6 N/cm2, averaging 7.9 N/cm2, among all tested meat products. The plant-based matrices, however, ranged between 0.2 and 1.3 N/cm2.
Thus, the tensile strength values of the plant-based matrices only reached the lower edge of the range for comparable meat products. Yet all four tested characteristics were in comparable regions, especially samples with higher dry matter, gluten and pectin contents. It should be noted, though, that texture profile analysis only allows for a limited comparison in terms of actual texture perception. These results only give a broad estimate of the model matrices’ qualitative suitability to act as raw fermented sausage analogs. Further evaluations, such as sensorial analysis and oral processing, are required to understand which food structure causes what kind of change in the chewing process [76].
The influence of the embedded particles (TVP + fat gel) on the textural properties of the whole system should also not be neglected. They both may act as active fillers, and their individual properties, as well as their interplay with the continuous matrix, are essential for the textural characteristics of the composite product [77,78]. Additionally, textural properties of different hydrocolloids vary widely, as shown in numerous studies [79,80]. When applied combined, e.g., alginate/pectin mixed gels, further synergistic effects have been reported [81]. The use of different starter cultures can also have a distinct influence on the textural attributes of fermented products [82,83]. Therefore, with the large variety of LM pectins, as well as other potential hydrocolloids, TVPs, fat replacers and starter cultures, in commercial markets, a large toolbox of potential levers for texture and flavor adjustments is becoming available.

3.4. Sensorial Analysis

Samples were cut in 1 mm thick slices (cold cuts) in order to be tasted. First bites were generally described as good and product-typical; however, the slices were described as too easy to tear when bitten into and could not reach the typical high tear resistance of salami cold cuts. This tensile strength improved with higher pectin, gluten and dry matter contents, which is in line with the texture analysis, as hardness and tensile strength were increased in similar samples as well. With lower pectin contents, the matrix also showed decreased strength and increased brittleness.
After prolonged chewing, higher gluten contents combined with low dry matter contents led to the matrix forming a rather elastic gluten mass in the mouth; hence, at the beginning of the chewing phase, ‘high pectin–high gluten–high dry matter’ was preferred, whereas at the end of the chewing phase, ‘high pectin–low gluten–high dry matter’ was preferred.
The smell of the product was described as very good, product-typical and sourly fermented with savory notes; the same applied to the aroma. Here, however, the fermentative aroma was overshadowed by too much acidity (see Figure 4) and described as ‘product-typical fermentation aroma’, ‘peppery/spicy finish’, an ‘intense, sour–salty taste’ and a ‘slightly beany aftertaste’. This, hence, can be further improved by adapted choice of starter culture (e.g., mildly acidifying heterofermentative LAB), adapted choice of ingredients (e.g., TVP with a lower carbohydrate content and/or a higher buffering capacity) or adapted process control (lower process temperature and faster drying via a smaller sausage caliber).
The juiciness of the matrix was described as sufficient but decreasing with high dry matter content. In addition to the water content, juiciness is also strongly influenced by the amount of free fat in the matrix. With all of the oil being bound in stable emulsion gels, the lubricating effect of fat leaking into the matrix is missing and the sample appears drier [77,78]. A better-suited fat alternative must be found in the long term.

3.5. Food Safety

Fermentation flora [aerobic mesophilic cfu] measured after 21 days were found to be between 5.8 × 107 cfu/g and 4.1 × 108 cfu/g, levels that are considered typical for fermented products. Further details can be found in Table 4. Escherichia coli, Listeria monocytogenes and Salmonella spp. were not detected in any of the samples, and the samples were thus deemed safe for consumption. The aw values (0.926 to 0.916), combined with the observed pH values (pH 4.3–4.5) as well as the additional applied hurdles (protective cultures, salt content, smoking, vacuum packaging after drying and storage at 15 °C), were sufficient to guarantee the food safety of the raw-fermented plant-based salami analogs.
As noted previously, with increasing pectin concentration in the matrix, both the pH and aw values decreased, which made for a somewhat safer environment in the matrix. This, however, did not prove to be of significance under the tested parameters, since the values achieved during fermentation and drying were dominant here. For more practice-oriented applications it will be crucial to find a good balance between sufficient acidity for a safe product and an appropriate acidity for a mild, pleasant taste similar to the one that traditional raw-fermented sausages provide (~pH 4.8–5.5 [66,67]). This could be accomplished by use of bacterial strains tailored to the plant-based matrix. Food safety will have to be re-examined then, though, considering that plant-based materials typically show moderate vital cell and spore contaminations with a large variety of strains, including Listeria monocytogenes and Bacillus cereus, due to their cultivation, harvesting and processing conditions [84].

3.6. Limitations of This Study

As this study provides the basis for a novel unheated fermented vegan meat analog, the focus of the work was on the basic feasibility of such a product. However, the focus and the scientific depth of research on many topics that deserve more attention and urgently need it in order to illuminate the proposed methodology from all sides fell by the wayside. First of all, the gelling kinetics and all the influencing factors should be examined more closely to be able to ensure a controlled gelling reaction. Furthermore, the resulting network structure, including the molecular interactions between constituents, must be analyzed. Apart from the loss of data that impaired the TPA, texture analyses can only ever provide limited information about the actual textural properties. Hence, further rheological, tribological but above all sensory investigations with a broad panel are required to provide adequate assessments of the matrix characteristics. Further aspects that have not been sufficiently addressed here are the effects of long-term fermentation on the matrix. The focus here lies particularly on the development of desired aroma and texture using different strain and substrate combinations. However, food safety should also be re-evaluated, especially in the context of spore formers, which were not examined here, and in the case of alternative ripening and storage conditions. Finally, possible fermentative degradation and oxidation products that may arise during fermentation and storage should also be investigated. This is not only relevant to preventing the formation of rancid flavors but also the formation of potentially harmful substances like biogenic amines.

4. Conclusions

The results of this study have shown that the manufacture of a raw-fermented (unheated) plant-based salami analog is feasible. The manufactured product remained unheated for 21 days of ripening; developed a firm, sliceable structure; and remained safe for consumption. The proposed methodology inducing low-ester pectin gelation via calcium carbonate slowly released by acid after the processing performed as intended, forming a strong network in combination with gluten. The gelation occurred in a time-delayed fashion, due to the low solubility of calcium carbonate in water, with starter cultures generating sufficient quantities of lactic acid over time. However, due to the low intrinsic pH of the pectin solution (pH = 4.2), a partial gelling reaction of low-ester pectin with calcium occurred gradually over time before the fermentation started, especially in the first 60 min after mixing. Provided that filling can happen fairly directly after mixing, the proposed method can be successfully applied; however, in the long term, an improved calcium delivery system via complexation or an equivalent should be considered.
The gels were able to bind particulate substances such as texturized proteins (TVPs) and solid fat. Both gluten and low-ester pectin had a significant influence on the overall properties of the matrices, especially with respect to water holding capacity, hardness, tensile strength and cohesiveness. A combination of three simultaneously occurring effects was observed, modulating the properties of the matrices, namely, (a) an increase in pectin gel strength due to increased pectin concentration forming more brittle gels, (b) an increase in gluten gel strength with increasing gluten content forming more elastic gels, and (c) interactions of low-ester pectin with the gluten network, with pectin addition causing increased aggregation of gluten, leading to further strengthening of gluten networks. In a tasting, the first bites of the vegan cold cuts were described as generally good and product-typical; however, they were also described as too easy to tear when bitten into and could not reach the typical high tear resistance of salami cold cuts. The smell of the product was described as very good, product-typical and sourly fermented with savory notes; the same applied to the aroma. Here, however, the fermentative aroma was overshadowed by too much acidity.
With the large amount of gluten and hydrocolloids on the market, our study demonstrates that a large toolbox for further texture optimization is available. Fillers such as plant protein texturates and solid-fat mimetics may further be modulated to optimize the textural properties of such systems. Moreover, the choice of starter cultures will clearly be of great importance, especially when it comes to the effects of flavor development over longer periods of time, a fact that will be investigated in future studies. Finally, the results may be translatable to a larger variety of raw-fermented plant-based products, other than salami analogs, offering the option of developing novel fermented products such as raw-fermented plant-based ham, cheese, yoghurt or curd.

Supplementary Materials

The following supporting information can be downloaded at https://www.mdpi.com/article/10.3390/app15158510/s1: Preliminary trials. References [85,86,87,88,89,90,91,92,93,94,95,96,97,98] are cited in the supplementary materials

Author Contributions

M.K.: Conceptualization, Methodology, Investigation, Visualization, Writing—original draft. K.A.: Conceptualization, Investigation, Methodology. K.H.: Conceptualization, Investigation, Methodology. M.L.: Funding acquisition, Project administration, Supervision, Writing—review and editing. J.W.: Conceptualization, Funding acquisition, Supervision, Writing—review and editing. All authors have read and agreed to the published version of the manuscript.

Funding

This IGF Project of the FEI (Forschungskreis der Ernährungsindustrie e.V., Bonn, Germany) was supported via AiF [21931N] within the program for promoting the Industrial Collective Research (IGF) of the German Federal Ministry for Economic Affairs and Energy (BMWE) on the basis of a decision by the German Bundestag.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Data will be made available on request.

Conflicts of Interest

The authors declare no conflicts of interest.

Abbreviations

The following abbreviations are used in this manuscript:
PBMAsPlant-based meat analogs
DEDegree of esterification
LMLow-methoxylated
LABLactic acid bacteria
TVPTextured vegetable protein
RHRelative humidity
CFUColony-forming units
ANOVAAnalysis of variance
TPATexture profile analysis

Appendix A

Table A1. Spices and colorants used in the vegan salami model matrix.
Table A1. Spices and colorants used in the vegan salami model matrix.
IngredientsAmount (%)
Salt1.7
Salami aroma0.7
Garlic paste0.5
Paprika powder0.4
Pepper0.2
CaCO30.1
Colorants
Beetroot powder0.4
FeOx0.04
Total4.04

Appendix B

Applsci 15 08510 g0a1
Figure A1. Food safety analysis report, page 1, with internal labeling: ‘Batch 1 = 15% glut. 1% pec.’; ‘Batch 2 = 15% glut. 3% pec.’; ‘Batch 3 = 15% glut. 5% pec.’.
Figure A1. Food safety analysis report, page 1, with internal labeling: ‘Batch 1 = 15% glut. 1% pec.’; ‘Batch 2 = 15% glut. 3% pec.’; ‘Batch 3 = 15% glut. 5% pec.’.
Applsci 15 08510 g0a1
Applsci 15 08510 g0a2
Figure A2. Food safety analysis report, page 2, with internal labeling: ‘Batch 1 = 15% glut. 1% pec.’; ‘Batch 2 = 15% glut. 3% pec.’; ‘Batch 3 = 15% glut. 5% pec.’.
Figure A2. Food safety analysis report, page 2, with internal labeling: ‘Batch 1 = 15% glut. 1% pec.’; ‘Batch 2 = 15% glut. 3% pec.’; ‘Batch 3 = 15% glut. 5% pec.’.
Applsci 15 08510 g0a2

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Figure 1. Production scheme of the raw-fermented plant-based salami analog matrices, with additional depictions of several processing steps as well as the final product after ripening for 21 days (sausage without casing at 65% dry matter).
Figure 1. Production scheme of the raw-fermented plant-based salami analog matrices, with additional depictions of several processing steps as well as the final product after ripening for 21 days (sausage without casing at 65% dry matter).
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Figure 2. Model system for a plant-based salami-type sausage analog based on low-moisture-extruded plant protein fibers and solid-fat particles, bound by the proposed binding system based on pectin and gluten.
Figure 2. Model system for a plant-based salami-type sausage analog based on low-moisture-extruded plant protein fibers and solid-fat particles, bound by the proposed binding system based on pectin and gluten.
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Figure 3. Effects of acidification by starter cultures and intermediate storage time between mixing and filling of the plant-based salami analog mass on the final product texture. Sample masses were filled into sealable cups (n = 8) after varying storage times at 15 °C. Once filled, they ripened for 24 h at 25 °C and then for 72 h at 15 °C and were subsequently analyzed.
Figure 3. Effects of acidification by starter cultures and intermediate storage time between mixing and filling of the plant-based salami analog mass on the final product texture. Sample masses were filled into sealable cups (n = 8) after varying storage times at 15 °C. Once filled, they ripened for 24 h at 25 °C and then for 72 h at 15 °C and were subsequently analyzed.
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Figure 4. Weight loss and pH courses of the different plant-based salami analogs, all with identical base masses, varying only in binder composition (pectin/gluten), during 8 days of drying.
Figure 4. Weight loss and pH courses of the different plant-based salami analogs, all with identical base masses, varying only in binder composition (pectin/gluten), during 8 days of drying.
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Figure 5. Exemplary cross sections of the plant-based salami analogs varying only in binder composition (pectin/gluten) after 21 days of ripening at 15 °C, dried to equal dry matter contents of 65%.
Figure 5. Exemplary cross sections of the plant-based salami analogs varying only in binder composition (pectin/gluten) after 21 days of ripening at 15 °C, dried to equal dry matter contents of 65%.
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Figure 6. Texture profile analysis of plant-based salami analog samples, all with identical base masses, varying only in binder composition (pectin/gluten), with (a) hardness, (b) springiness and (c) cohesiveness measured via double compression test and (d) tensile strength measured via rupture test. Samples were dried to equal dry matter (DM) contents of 55% and 65% and ripened for 21 days at 15 °C. Statistical differences are indicated by reference letters a-b-c (pectin concentration), K-L (dry matter content) and X-Y (gluten concentration).
Figure 6. Texture profile analysis of plant-based salami analog samples, all with identical base masses, varying only in binder composition (pectin/gluten), with (a) hardness, (b) springiness and (c) cohesiveness measured via double compression test and (d) tensile strength measured via rupture test. Samples were dried to equal dry matter (DM) contents of 55% and 65% and ripened for 21 days at 15 °C. Statistical differences are indicated by reference letters a-b-c (pectin concentration), K-L (dry matter content) and X-Y (gluten concentration).
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Table 1. Initial production composition of plant-based raw-fermented salami analog matrices, all with identical base masses, varying only in binder composition (pectin/gluten).
Table 1. Initial production composition of plant-based raw-fermented salami analog matrices, all with identical base masses, varying only in binder composition (pectin/gluten).
IngredientsSausage Composition (%)
15% Glut.
1% Pec.		15% Glut
3% Pec.		15% Glut.
5% Pec.		10% Glut.
1% Pec.		10% Glut.
3% Pec.		10% Glut.
5% Pec.
Spices *4.044.044.044.044.044.04
Fat gel12.9612.9612.9612.9612.9612.96
TVP **141414141414
Binder696969696969
Binder consisting of
Water535149585654
Gluten151515101010
Pectin135135
Dry matter363840313335
* Spices in Appendix A, ** soaked in water–TVP (2:1).
Table 2. Water activity values of plant-based raw-fermented salami analogs, all with identical base masses, varying only in binder composition (pectin/gluten), at different time points throughout the drying and ripening process.
Table 2. Water activity values of plant-based raw-fermented salami analogs, all with identical base masses, varying only in binder composition (pectin/gluten), at different time points throughout the drying and ripening process.
Batch Compositionaw Values (-)
In Raw BatterAt 55% Dry MatterAt 65% Dry Matter
15% glut.–1% pec.0.971 ± 0.0010.933 ± 0.0030.922 ± 0.002
15% glut.–3% pec.0.968 ± 0.0010.931 ± 0.0010.920 ± 0.001
15% glut.–5% pec.0.967 ± 0.0010.927 ± 0.0010.916 ± 0.002
10% glut.–1% pec.0.979 ± 0.0000.937 ± 0.0030.926 ± 0.000
10% glut.–3% pec.0.977 ± 0.0010.935 ± 0.0010.926 ± 0.002
10% glut.–5% pec.0.966 ± 0.0010.932 ± 0.0000.922 ± 0.001
Table 3. Chemical analysis (water, protein, ash, fat and carbohydrate contents) of the different plant-based raw-fermented salami analogs, all with identical base masses, varying only in binder composition (pectin/gluten), measured in the raw batter.
Table 3. Chemical analysis (water, protein, ash, fat and carbohydrate contents) of the different plant-based raw-fermented salami analogs, all with identical base masses, varying only in binder composition (pectin/gluten), measured in the raw batter.
Batch
Composition		Water
Content (%)		Protein
(%)		Ash
(%)		Fat
(%)		Carbohydrates
* (%)
15% glut.–1% pec.59.90 ± 0.3119.39 ± 1.522.89 ± 0.0210.69 ± 0.037.13 ± 1.87
15% glut.–3% pec.58.06 ± 0.3319.68 ± 0.332.90 ± 0.0310.14 ± 0.039.22 ± 0.72
15% glut.–5% pec.56.18 ± 0.0719.34 ± 0.392.85 ± 0.0110.56 ± 1.2511.07 ± 1.72
10% glut.–1% pec.65.94 ± 0.2315.11 ± 0.782.58 ± 0.029.94 ± 0.566.43 ± 1.59
10% glut.–3% pec.63.15±0.2814.89 ± 0.552.61 ± 0.0210.21 ± 0.119.14 ± 0.96
10% glut.–5% pec.60.66 ± 0.1914.96 ± 0.482.65 ± 0.0410.48 ± 0.1311.25 ± 0.84
* Calculated.
Table 4. Assessment of microbiological quality of the raw-fermented plant-based sausage analogs with 65% dry matter after 21 days of fermentation at 15 °C only.
Table 4. Assessment of microbiological quality of the raw-fermented plant-based sausage analogs with 65% dry matter after 21 days of fermentation at 15 °C only.
Batch
Composition		Aerobic Mesophilic Colony Count
‘Fermentation Flora’
(CFU/g)		Escherichia coli
(CFU/g)		Listeria mono-
cytogenes
(CFU/g)		Salmonella spp.
(CFU/25 g)
15% glut.–1% pec.2.4 × 108n.d. (<101)n.d. (<101)n.d. (<101)
15% glut.–3% pec.5.8 × 107n.d. (<101)n.d. (<101)n.d. (<101)
15% glut.–5% pec.4.1 × 108n.d. (<101)n.d. (<101)n.d. (<101)
n.d. = not detectable; CFU = colony-forming units.
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Koenig, M.; Ahlborn, K.; Herrmann, K.; Loeffler, M.; Weiss, J. Time-Delayed Cold Gelation of Low-Ester Pectin and Gluten with CaCO3 to Facilitate Manufacture of Raw-Fermented Vegan Sausage Analogs. Appl. Sci. 2025, 15, 8510. https://doi.org/10.3390/app15158510

AMA Style

Koenig M, Ahlborn K, Herrmann K, Loeffler M, Weiss J. Time-Delayed Cold Gelation of Low-Ester Pectin and Gluten with CaCO3 to Facilitate Manufacture of Raw-Fermented Vegan Sausage Analogs. Applied Sciences. 2025; 15(15):8510. https://doi.org/10.3390/app15158510

Chicago/Turabian Style

Koenig, Maurice, Kai Ahlborn, Kurt Herrmann, Myriam Loeffler, and Jochen Weiss. 2025. "Time-Delayed Cold Gelation of Low-Ester Pectin and Gluten with CaCO3 to Facilitate Manufacture of Raw-Fermented Vegan Sausage Analogs" Applied Sciences 15, no. 15: 8510. https://doi.org/10.3390/app15158510

APA Style

Koenig, M., Ahlborn, K., Herrmann, K., Loeffler, M., & Weiss, J. (2025). Time-Delayed Cold Gelation of Low-Ester Pectin and Gluten with CaCO3 to Facilitate Manufacture of Raw-Fermented Vegan Sausage Analogs. Applied Sciences, 15(15), 8510. https://doi.org/10.3390/app15158510

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