Search Results (14)

Some of the main factors affecting the product quality and shelf life of cheese include weight loss during storage, microbial spoilage, and structural changes in processing technology. Edible films are coating materials produced with the aim of improving quality properties and extending shelf life, and various studies have been conducted on their properties. However, research examining the effects of coatings enriched with spice-derived natural antimicrobial compounds is scarce in relation to cheese quality. In this study, edible films and spice mixtures were applied to cheese during storage, and their effects on weight loss, textural properties, and microbiological stability were investigated. Response surface methodology was used to determine the edible films and spice mixtures used in the coatings. The amounts of whey protein isolate and konjac glucomannan in the composition of edible films were found to affect water vapor permeability, elongation coefficient, and tensile strength properties; in the spice mixtures, thyme, rosemary, and red pepper were found to have antifungal effects. Based on the data obtained, it was determined that applying an edible film coating to the cheese surface reduced weight loss and improved textural properties, while applying a spice mixture coating increased microbial stability. This study demonstrates that the use of edible films supported by natural protective components could be a practically applicable, innovative, and sustainable approach to improving the properties of cheese and extending its shelf life. Full article

Manouri is a Greek whey cheese, with a Protected Denomination of Origin recognition, produced by heating the cheese whey and added milk and/or cream at high temperatures (88–90 °C) to form a coagulum. High-heat treatment results in the inactivation of any indigenous microorganisms from the raw materials. However, the high moisture, fat and pH of the cheese make it a favorable medium for the growth of any microbial contamination. The objective of this study was to investigate the application of a commercial protective culture (CPC) on the microbial profile of Manouri cheese during storage. Three treatments were prepared: S1 was the control cheese with sterile water sprayed on the surface, S2 was sprayed with a dense CPC and S3 with a diluted CPC. The experimental cheeses were covered with greaseproof paper and stored at 5 °C for 21 days. For all three treatments, the fat content and total solids showed a significant increase during storage, while protein and carbohydrates showed a significant decrease at 14 days. The application of the CPC resulted in cheeses with higher pH than the control cheese, probably due to the growth of acidifying lactic acid bacteria in the microbiota of the S2 and S3 cheeses. Manouri cheese sprayed with the CPC showed a reduction of 1.60–1.69 log CFU/g in the population of yeasts; no effect was observed on Enterobacteriaceae and Staphylococcus spp. The dominant yeast microbiota was identified as Candida zeylanoides (63.5%), Candida parapsilosis (21.1%) and Candida famata (15.4%). Although the application of the CPC was not able to control the spoilage bacteria, it showed an effective way to control the growth of yeasts in Manouri cheese. However, the presence of certain Candida spp. reveals the significance of applying good hygiene practices throughout the cheesemaking process. Full article

Different solvents water, ethanol and ethanol/water (6:4 v/v), were compared in the extraction of pomegranate peels and seeds (PPS) in terms of recovery yields, antioxidant properties, and antimicrobial action against typical spoilage bacterial and fungal species. The best performing extract (ethanol/water (6:4 v/v) was shown to contain mostly ellagic acid and punicalagin as phenolic compounds (5% overall) and hydrolysable tannins (16% as ellagic acid equivalents) and was able to inhibit the growth of the acidophilic Alicyclobacillus acidoterrestris at a concentration as low as 1%. The preservation of the organoleptic profile of A. acidoterrestris-inoculated apple juice with extract at 1% over 20 days was also observed thanks to the complete inhibition of bacterial growth, while the extract at 0.1% warranted a significant (40%) inhibition of the enzymatic browning of apple smoothies over the first 30 min. When incorporated in whey proteins’ isolate (WPI) at 5% w/w, the hydroalcoholic extract conferred well appreciable antioxidant properties to the resulting coating-forming hydrogel, comparable to those expected for the pure extract considering the amount present. The WPI coatings loaded with the hydroalcoholic extract at 5% were able to delay the browning of cut fruit by ca. 33% against a 22% inhibition observed with the sole WPI. In addition, the functionalized coating showed an inhibition of lipid peroxidation of Gouda cheese 2-fold higher with respect to that observed with WPI alone. These results open good perspectives toward sustainable food preservation strategies, highlighting the potential of PPS extract for the implementation of WPI-based active packaging. Full article

A species-specific multiplex-PCR method and phenotypic tests were combined to evaluate biochemical and genotypic differences between 24 representative Leuconostoc mesenteroides diverse isolates previously found to dominate in spoiled, vacuum-packed Anthotyros whey cheeses stored at 4 °C for 40 days and identified by 16S rRNA gene sequencing. Based on their phenotypic (API 50 CHL) profiles, the 24 isolates comprised 6 multi-strain and 7 single-strain biotypes. Only two single-strain biotypes (L4A and L4B) produced slime (dextran) from sucrose, and only four biotypes (L2A–L2C, L3; 7 isolates) fermented L-arabinose; the remaining 15 isolates (biotypes L1A–L1F) were dextran-negative, oligofermenting Ln. mesenteroides variants, able to ferment D-xylose and grow at 37 °C. Based on their multiplex-PCR (rpoB, araA, dsr, and sorA) gene profiles in comparison with those of the type strains of the four Ln. mesenteroides subsp. cremoris (rpoB), dextranicum (rpoB/dsr), mesenteroides (rpoB/araA/dsr/sorA), and jonggajibkimchii (rpoB/araA/dsr), no isolate was assigned to the first two subspecies and only four isolates (L2A and L2C) to the subsp. mesenteroides. Ten isolates shared the subsp. jonggajibkimchii profile, while the other ten ones have a fifth atypical profile (rpoB/dsr/sorA), seemingly being closer to the subsp. dextranicum. Particularly the atypical biotype L1B representatives of the most prevalent psychrotrophic Ln. mesenteroides subsp. jonggajibkimchii (rpoB/araA/dsr) genotype at Anthotyros whey cheese spoilage deserve further biochemical and molecular characterization studies. Full article

Biodegradable packaging, both alone and in combination with acid whey protein coatings, has been used to pack fresh Gouda cheese to improve preservation prior ripening or storage. This study involved three key components: (i) the selection of biodegradable packaging (BP), (ii) the development of a plain liquid acid whey protein concentrate, pectin-based edible coating (BP + Ch + Coating), and (iii) the incorporation of at least 6 log₁₀ CFU (colony forming units) mL⁻¹ Lacticaseibacillus paracasei (BP + Ch + Coating + Lp) and Lactobacillus helveticus (BP + Ch + Coating + Lh) strains. The created compositions were compared with cheese packed in conventional polyethylene (PE) packaging to evaluate their overall synergy effect in reducing microbiological spoilage and influencing chemical parameters in Gouda cheese during 45 days of ripening and cold storage. The evaluation included microbiological analysis (total LAB, Enterobacteriaceae spp., and fungi CFU) and quality assessment of pH, moisture content, water activity, texture, and colour (CEI system) during ripening and shelf life. Although biodegradable packaging (BP) alone did not protect the cheese effectively compared to conventional packaging (EVA/PE/EPC/PVDC), the combination of biodegradable packaging with a coating (BP + Ch + Coating) showed protective properties against Enterobacteriaceae spp. and mould, maintaining moisture, pH, and colour during ripening and storage. Incorporation of L. helveticus (BP + Ch + Coating + Lh) into the coating efficiently decreased the growth of fungi. Full article

The cheese rind is the natural food packaging of cheese and is subject to a wide range of external factors that compromise the appearance of the cheese, including color defects caused by spoilage microorganisms. First, eight films based on whey protein isolate (WPI) coatings were studied, of which IS3CA (WPI 5% + sorbitol 3% + citric acid 3%) was selected for presenting better properties. From the IS3CA film, novel films containing melanin M1 (74 µg/mL) and M2 (500 µg/mL) were developed and applied to cheese under proof-of-concept and industrial conditions. After 40 days of maturation, M2 presented the lowest microorganism count for all the microbial parameters analyzed. The cheese with M2 showed the lowest lightness, which indicates that it is the darkest cheese due to the melanin concentration. It was found that the mechanical and colorimetric properties are the ones that contribute the most to the distinction of the M2 film in cheese from the others. Using FTIR-ATR, it was possible to distinguish the rinds of M2 cheeses because they contained the highest concentrations of melanin. Thus, this study shows that the film with M2 showed the best mechanical, chemical and antimicrobial properties for application in cheese. Full article

The aim of this study was to reveal the sites of yeast contamination in dairy production and perform taxonomic characterization of potential yeast spoilers in cheese making. Occurrence of spoilage yeasts was followed throughout the manufacture of white-brined cheese at a Danish dairy, including the areas of milk pasteurization, curd processing, and packaging (26 sites in total). Spoilage yeasts were isolated from whey, old cheese curd, and air samples in viable counts of 1.48–6.27 log CFU/mL, 5.44 log CFU/g, and 1.02 log CFU/m³, respectively. Yeast isolates were genotypically classified using (GTG)₅-PCR fingerprinting and identified by sequencing of the D1/D2 region of the 26S rRNA gene. The largest yeast heterogeneity was found in old curd collected under the turning machine of molds, where 11 different yeast species were identified. The most frequently isolated yeast species were Candida intermedia, Kluyveromyces marxianus, and Pichia kudriavzevii. The less abundant yeast species included Candida auris, Candida parapsilosis, Candida pseudoglaebosa, Candida sojae, Cutaneotrichosporon curvatus, Cutaneotrichosporon moniliiforme, Papiliotrema flavescens, Rhodotorula mucilaginosa, Vanrija humicola, and Wickerhamiella sorbophila. The awareness on occurrence and taxonomy of spoilage yeasts in cheese production will contribute to a knowledge-based control of contaminating yeasts and quality management of cheese at the dairies. Full article

Effective biopreservation measures are needed to control the growth of postprocess Listeria monocytogenes contamination in fresh whey cheeses stored under refrigeration. This study assessed growth and biocontrol of inoculated (3 log₁₀ CFU/g) L. monocytogenes in vacuum-packed, fresh (1-day-old) or ‘aged’ (15-day-old) Anthotyros whey cheeses, without or with 5% of a crude enterocin A-B-P extract (CEntE), during storage at 4 °C. Regardless of CEntE addition, the pathogen increased by an average of 2.0 log₁₀ CFU/g in fresh cheeses on day 15. Gram-negative spoilage bacteria also increased by an average of 2.5 log₁₀ CFU/g. However, from day 15 to the sell-by date (days 35–40), L. monocytogenes growth ceased, and progressively, the populations of the pathogen declined in most cheeses. This was due to an unmonitored, batch-dependent natural acidification by spoilage lactic acid bacteria, predominantly Leuconostoc mesenteroides, which reduced the cheese pH to 5.5, and finally to ≤5.0. The pH reductions and associated declines in pathogen viability were greater in the CEntE-treated samples within each batch. L. monocytogenes failed to grow in cheeses previously ‘aged’ in retail for 15 days. Overall, high population levels (>7.5 log₁₀ CFU/g) of psychrotrophic Enterobacteriaceae, particularly Hafnia alvei, were associated with an extended growth and increased survival of L. monocytogenes during storage. Full article

Although fresh whey cheeses are prone to rapid deterioration, mainly by psychrotrophic Gram-negative bacteria and lactic acid bacteria (LAB), data on the specific spoilage species in traditional Greek whey cheeses are scarce. Therefore, this study quantified growth and characterized the primary spoilage bacteria in fresh Anthotyros whey cheeses stored at 4 °C in a vacuum for 40 days, without or with an added 5% (v/w) of an enterocin A-B-P crude extract (CEntE). Psychrotrophic Pseudomonas spp., Aeromonas spp., Hafnia spp. and Serratia spp. grew faster than LAB during early storage. However, LAB outgrew the Gram-negative bacteria and prevailed by mid to late storage in all cheese batches, causing a strong or milder batch-dependent natural acidification. Two major non-slime-producing and two minor biotypes of Leuconostoc-like bacteria, all identified as Leuconostoc mesenteroides by 16S rRNA sequencing, dominated the LAB association (76.7%), which also included four subdominant Carnobacterium maltaromaticum biotypes (10.9%), one Leuconostoc lactis biotype (3.3%) and few Lactococcus (1.6%), mesophilic Lactobacillus (0.8%) and Enterococcus (0.8%). Growth and distribution of LAB and Gram-negative species were strongly batch-dependent and plant-dependent. The CEntE neither retarded growth nor altered the whey cheese spoilage association but enhanced LAB growth and the declines of Gram-negative bacteria by late storage. Full article

Whey is the main byproduct of the dairy industry and contains sugars (lactose) and proteins (especially serum proteins and, at lesser extent, residual caseins), which can be valorized by the fermentative action of yeasts. In the present study, we characterized the spoilage yeast population inhabiting natural whey starter (NWS), the undefined starter culture of thermophilic lactic acid bacteria used in Parmigiano Reggiano (PR) cheesemaking, and evaluated thermotolerance, mating type, and the aptitude to produce ethanol and bioactive peptides from whey lactose and proteins, respectively, in a selected pool of strains. PCR-RFLP assay of ribosomal ITS regions and phylogenetic analysis of 26S rDNA D1/D2 domains showed that PR NWS yeast population consists of the well-documented Kluyveromyces marxianus, as well as of other species (Saccharomyces cerevisiae, Wickerhamiella pararugosa, and Torulaspora delbrueckii), with multiple biotypes scored within each species as demonstrated by (GTG)₅-based MSP-PCR. Haploid and diploid K. marxianus strains were identified through MAT genotyping, while thermotolerance assay allowed the selection of strains suitable to grow up to 48 °C. In whey fermentation trials, one thermotolerant strain was suitable to release ethanol with a fermentation efficiency of 86.5%, while another candidate was able to produce the highest amounts of both ethanol and bioactive peptides with potentially anti-hypertensive function. The present work demonstrated that PR NWS is a reservoir of ethanol and bioactive peptides producer yeasts, which can be exploited to valorize whey, in agreement with the principles of circularity and sustainability. Full article

Parmigiano Reggiano is a hard PDO cheese made from bovine raw milk, whose microbiological characteristics have important repercussions on cheese quality. According to the EU official production protocol, milk temperature at the farm must not drop below 18 °C. The present research aimed to study the effect of cooling milk at the farm at 9 °C on the characteristics of milk and on the cheesemaking process and losses during manufacture. Six cheesemaking trials were performed in two different dairies. In each of them, two cheesemakings were made in parallel: one with milk kept at 9 °C (TM9) and the other with milk kept at 20 °C (TM20). TM9 milk, in comparison with TM20, showed after the creaming process a significant reduction not only of total bacterial count but also of psychrotrophic and lipolytic bacteria. At the same time, TM9 milk showed a higher creaming capacity and, consequently, a lower fat content than TM20. TM9 vat milk had worst coagulation properties than TM20, which caused slightly higher loss of fat and curd fines into the whey. Nevertheless, these changes were too small to influence the efficiency of the cheesemaking process; conversely, maintaining milk at the farm at 9 °C led to a reduction of the number of spoilage bacteria. Full article

In the present study, cheese whey was utilized for the development of a novel functional beverage, using Lactobacillus casei ATCC 393 probiotic cells immobilized on Pistacia terebinthus resin (pissa Paphos). Evaluation of shelf life of the produced beverages showed that spoilage microorganisms were not observed in beverages containing P. terebinthus resin. Terpenes’ rich content might have contributed to the antimicrobial activity of the produced beverages; however, no significant effect on the viability of the immobilized probiotic cells was obtained. Whey beverages containing the immobilized biocatalyst retained a high viability (>1 × 10⁶ CFU/g) of probiotic cells during a storage period of 30 days at 4 °C. The superiority of whey beverages containing the immobilized biocatalyst was also highlighted by GC-MS analysis, while the enhanced aromatic profile, which was mostly attributed to the higher concentration of terpenes, was also detected during the sensory evaluation performed. Conclusively, this study indicated the high commercialization potential of these novel functional whey beverages, within the frame of a sustainable dairy waste valorization approach. To the best of our knowledge, this is the first food-oriented approach within the guidelines of the circular economy reported in the literature, using the autochthonous Pistacia terebinthus resin for the production of functional whey beverages. Full article

Cheese whey has been described as an environmental hazard due to its high organic content. Although it has been suggested that whey can be used as food disinfectant, it continues to pose an environmental problem because it still contains a high organic load. Here, we aimed to develop a low-cost, scalable fermentation protocol to produce a disinfectant from dairy waste that has very little organic content and high levels of lactic acid. Fermentation was achieved with industrial whey from ewe, goat, and cow’s milk, using a specific mesophilic-lactic acid bacteria starter mix over 120 h, which yielded the highest lactic acid production and the lowest lactose content. Antibacterial activity was observed against Listeria monocytogenes, Salmonella enterica, and Escherichia coli O157:H7, plus a total of thirteen other food pathogenic and spoilage strains, and antibacterial activities were determined to be highest after 120 h. We further validated this whey’s application as a disinfectant in shredded lettuce and compared its efficacy to that of chlorine, evaluating microbial quality, texture, color, and sensory perception, pH, and O₂ and CO₂ determinations. Results showed that not only was microbial quality better when using our whey solution (p < 0.05), but also the quality indicators for whey were statistically similar to those treated with chlorine. Hence, our work validates the use of an industrial waste whey as a low-cost, efficient, and environmentally safe disinfectant, with potential applications for minimally processed foodstuffs as an alternative to chlorine. Full article

In the present study the effect of innovative biocatalysts as starter cultures in sourdough bread making was explored. The biocatalysts consisted of Lactobacillus paracasei K5 and Lactobacillus bulgaricus ATCC 11842 (in single and mixed form), immobilized on delignified wheat bran (DWB), and freeze dried without cryoprotectants. The parameters monitored were physicochemical characteristics, mold and rope spoilage appearance, volatile composition, and organoleptic characteristics. Results obtained showed that both biocatalysts exhibit good fermentative activity. However, the best results were achieved when freeze-dried immobilized L. paracasei K5 was applied as a single culture. In particular, the produced bread had a higher acidity (8.67 mL 0.1 N NaOH) and higher organic load (2.90 g/kg lactic acid and 1.11 g/kg acetic acid). This outcome was the main reason why this bread was preserved more regarding mold spoilage (14 days) and rope spoilage (12 days), respectively. In addition, the employment of freeze-dried immobilized L. paracasei K5 led to bread with better aromatic profile in terms of concentrations and number of volatile compounds produced as gas chromatography/mass spectrometry (GC/MS) analysis proved. Finally, no significant differences were observed through sensorial tests. Last but not least, it should be highlighted that the used microorganisms were cultured in cheese whey, minimizing the cost of the proposed biotechnological procedure. Full article