Microbial and Sensory Evaluation of Halophytes Cultivated in a Soilless System Under Different Salinities

Abstract

The increasing interest in halophytes as sustainable crops and their potential functional properties highlights the need to understand how cultivation conditions affect their quality for human consumption. The present study aimed to evaluate the influence of salinity on the microbial quality of the halophytes Disphyma crassifolium, Inula crithmoides, Mesembryanthemum nodiflorum, and Suaeda maritima, cultivated using a soilless system under different salinities. The sensorial quality of D. crassifolium and S. maritima was also assessed by an experienced panel of culinary chefs. The microbial quality was measured by counting aerobic microorganisms (30 °C and 6.5 °C), fungi, Escherichia coli, and coagulase-positive staphylococci. Salinity increase caused a concentration-dependent salt accumulation in the plants, triggering a rise in the microbial populations, namely aerobic and filamentous fungi on D. crassifolium and I. crithmoides and psychrotrophic microorganisms on S. maritima (p < 0.05). Except for M. nodiflorum, plants cultivated at the highest salinity (465 mM) had levels of filamentous fungi higher than 3 Log CFU/g. Concerning aerobes, plants presented a satisfactory microbiological quality (<6 Log CFU/g) even when cultivated at high salinity (465 mM), and yeasts, E. coli, and staphylococci were never detected. D. crassifolium and S. maritima cultivated at intermediate salinities were preferred by the sensory evaluation panel. In conclusion, soilless system cultivation produces plants adequate for consumption, considering their microbial and sensorial quality.

1. Introduction

Halophytes are plants adapted to thrive in environments with high salinity, such as coastlines, salt marshes, and mangroves [1,2]. The ability of halophytes to survive in extreme salinity is attributable to their morphophysiological strategies, such as salt exclusion, salt elimination by the root system, salt excretion through specialised organs (salt glands or salt bladders), and diluting ions using succulence mechanisms. The halophytic adaptation to salinity is also associated with some biochemical mechanisms, such as (a) ion homeostasis, involving various channels and transporters, to prevent salt entrance to the roots, and vacuolar compartmentalisation of ions; (b) the osmotic adjustment attained through uptake of inorganic ions, and the de novo synthesis of organic osmolytes, to maintain turgor pressure and organellar volume within the growing plant cells; and (c) efficient antioxidant defence mechanisms to protect plants from oxidative stress resultant from the accumulation of reactive oxygen species (ROS) produced under high salinity [3,4]. These adaptations allow halophytes not only to survive but to flourish in conditions that are inhospitable to most crops, but they may also interfere with the nutritional, microbial, and sensorial attributes, namely in their taste and texture, when these plants are used as foods. Recent research has highlighted the important ecological roles of halophytes, particularly in coastal ecosystems, where they contribute to erosion prevention, bioremediation of saline environments through pollutant removal, and the restoration of degraded soils via phytodesalination [2,5,6,7].

Among the most studied halophytes are Disphyma crassifolium (Aizoaceae), a low-growing annual succulent with round leaves and pink to violet flowers; Inula crithmoides (Asteraceae), a perennial succulent with fleshy green to yellow leaves reaching up to 1 m in height; Mesembryanthemum nodiflorum (Aizoaceae), an annual plant forming horizontal clumps with tender, salty, and acidic leaves; and Suaeda maritima (Amaranthaceae), characterised by branched stems and sessile curved leaves that turn red with age [8,9,10,11,12]. These species are commonly found in saline marshes and saltmarsh zones of the Mediterranean, as well as in regions such as Macaronesia and the Middle East [2,12]. These plants are increasingly recognised for their ecological resilience and economic potential in saline agriculture [5,13]. Their ability to thrive in marginal soils makes them keystone species for rehabilitating degraded coastal and arid ecosystems, stabilising sediments, and reducing soil salinity [3,7,14]. Economically, these plants offer sustainable alternatives for regions facing freshwater scarcity, with some species already commercialised in markets around the Mediterranean [15]. The integration of halophytes into soilless cultivation systems presents an opportunity to optimise yield, reduce land competition, and address global food security challenges intensified by climate change [16].

Beyond their ecological benefits, halophytes possess significant nutritional and medicinal value [17]. They are rich in bioactive compounds, including vitamins, carotenoids, polyphenols, omega-3 fatty acids, and flavonoids, some of which have demonstrated antihypertensive and antimicrobial effects [1,2,17,18]. For example, D. crassifolium is noted for its antioxidant activity; I. crithmoides contains relevant levels of vitamins B1, B6, β-carotene, and lutein; M. nodiflorum is a good source of vitamins A, C, and B6 and carotenoids, and S. maritima is associated with a wide range of metabolites and high antioxidant potential [2,11,18,19,20]. These nutritional attributes have led to increased interest in the agricultural production, commercialisation, and consumption of halophytes, both as functional foods and as novel ingredients in gourmet cuisine.

While the agronomic potential and phytochemical profiles of halophytes have been widely studied, their microbial quality, particularly under controlled cultivation conditions, such as soilless systems is rather unknown. Most research has focused on their growth and nutritional value, with limited attention given to how salinity regimes influence microbial populations in edible halophytes [2,12,17,21,22]. This is a significant concern, as halophytes, like all plants, are naturally colonised by diverse microbial communities, including bacteria, viruses, and fungi, which are usually non-pathogenic. However, the microbial quality of food is of concern, not only from the food safety point of view but also due to the spoilage associated with the decrease in shelf-life, which may result in vast commercial losses. The growth of microbial populations in foods leads to the deterioration of nutritional quality and is associated with the alteration of organoleptic properties. Notably, there are no established microbiological criteria specifically for halophytes under European Union food legislation, despite their increasing use as raw or cooked vegetables.

Considering the growing interest in the consumption and commercialisation of halophytes, this study investigated how different salinity levels in soilless cultivation systems affect not only the growth but also the microbiological and sensory quality of D. crassifolium, I. crithmoides, M. nodiflorum, and S. maritima. The research focused on the microbiological quality, including the presence of Escherichia coli and coagulase-positive Staphylococcus in these plants. In addition, the study examined the sensory properties of D. crassifolium and S. maritima, aiming to identify salinity ranges that balance food safety and consumer appeal, while the sensory characteristics of I. crithmoides and M. nodiflorum have already been described in a previous study. By bridging aspects of agricultural research with microbiological quality and sensory evaluation, this work aims to advance the practical utilisation of halophytes, providing evidence-based strategies for their safe and appealing production in controlled environments.

2. Materials and Methods

2.1. Experimental Setup and Halophyte Species

The study took place in a 200 m² polyethylene greenhouse at RiaFresh facilities (Portugal) from early spring to mid-autumn (March to October) under controlled conditions of temperature and relative humidity (%RH). The four species studied, D. crassifolium, M. nodiflorum, I. crithmoides, and S. maritima, were grown in a closed, soilless system, with seeds directly sown in the substrate within honeycombed trays. All halophyte species were developed under natural photoperiod and temperature. Figure 1 shows the species studied and cultivated in the greenhouse.

2.2. Growth Conditions

Six distinct salinity treatments (35, 110, 200, 275, 350, and 465 mmol L⁻¹ NaCl) were administered across three cultivation tables, each containing three randomly distributed trays. Each tray comprised one replicate per species, occupying about 0.18 m². The salinity levels were defined considering the range between a semi-saline medium (<40 mmol L⁻¹ NaCl) and the salinity of seawater (630 mmol L⁻¹ NaCl). Individual tanks with added NaCl dissolved in the nutrient solution represented each salinity level.

Nutrient solutions were prepared in 500 L tanks using fresh water from a well. Their composition (proprietary to RiaFresh^®) ensured balanced nutrition with all essential macro- and micronutrients, and no deficiencies were observed throughout the trial. An air pump and diffusion system provided continuous aeration. Simulated tidal irrigation involved two daily floods. Solution monitoring included daily pH (Hanna Instruments Portugal, Póvoa de Varzim, Portugal) and electrical conductivity (EC, dSm⁻¹, Hanna Instruments Portugal, Póvoa de Varzim, Portugal) measurements, with nitrate concentration (NO₃⁻, mg L⁻¹) assessed twice a week, following the procedure described by Hoather and Rackham [23]. Briefly, filtered samples were acidified and analysed for NO₃⁻ by absorption at 220 nm (corrected at 275 nm), using a UV–visible spectrophotometer (UV-160 A, Shimadzu, Kyoto, Japan). Nutritive solutions were refilled twice a week and completely replaced at least once a month.

Harvesting was performed when each species’ stem reached at least 20 cm. Pruning shears were used, and the fresh weight of collected biomass was immediately recorded. Productivity was quantified based on harvested aerial part fresh weight per area and time after sowing (g m⁻² day⁻¹). Relative productivity per salinity level was calculated as a percentage variation compared to the lowest salinity (35 mmol L⁻¹). For each treatment and replicate (at least six replicates of each cultivation condition), an aboveground biomass sample was collected, refrigerated, frozen (−20 °C), and freeze-dried before milling in a planetary ball mill (Retsch-PM 100, Retsch GmbH, Haan, Germany). Powdered samples were stored in a desiccator until analysis. The electrical conductivity (EC) was measured to translate the salty flavour of samples using a conductivity meter (Hanna Instruments Portugal, Póvoa de Varzim, Portugal).

2.3. Microbial Quality Evaluation

The microbial quality of the halophytes, Disphyma crassifolium, Inula crithmoides, Mesembryanthemum nodiflorum, and Suaeda maritima, cultivated using a soilless technique in three different concentrations (35, 200, and 465 mM of NaCl) was evaluated through the enumeration of aerobic microorganisms at 30 °C and 6.5 °C, filamentous fungi and yeasts, Escherichia coli, and coagulase-positive staphylococci, according to the International Organization for Standardization (ISO) standards ISO 4833-1:2013 [24], ISO 17410:2019 [25], ISO 21527-1:2008 [26], ISO 16649-2:2001 [27], and ISO 6888-1:2003 [28], respectively. For each analysis, 10 g of each plant was aseptically collected, mixed with 90 mL of sterile Ringer solution (Oxoid, Basingstoke, UK), and homogenised for 2 min (Model 400 Circulator, Seward, Norfolk, UK). Serial dilutions were performed using a sterile Ringer solution. The aerobic microorganisms at 30 °C were determined after the incorporation of aliquots of 1 mL in Plate Count Agar (PCA) (Scharlau, Barcelona, Spain) and incubated at the mentioned temperature for 3 days. The psychrotrophic aerobic microorganisms (6.5 °C) were determined by spread-plating aliquots of 0.1 mL onto the surface of the PCA, following incubation for 10 days.

Filamentous fungi and yeasts were counted on Dichloran Rose Bengal Chloramphenicol Agar Petri dishes (Scharlau, Barcelona, Spain) incubated at 25 ± 1 °C for 2 to 5 days. To enumerate E. coli, aliquots of 1 mL were inoculated in Chromocult Triptone Bile X-glucuronide Agar (TBX) (Merck, Darmstadt, Germany), following incubation at 44 °C for 24 h. The enumeration of the coagulase-positive staphylococci was performed by inoculating Baird-Parker medium (Oxoid) with 0.1 mL of the dilutions, followed by incubation at 37 °C during 24–48 h, according to the ISO 6888-1 [28]. The Staphylase Test (Oxoid) was used to test for the coagulase reaction of typical and atypical colonies. Aliquots of the dilutions were inoculated in duplicate, for all determinations.

The results were expressed as Log CFU/g of plant fresh weight. Experimental values are expressed as means ± standard deviation.

2.4. Sensory Analytical Method

Quantitative descriptive analysis (QDA) was employed to evaluate the organoleptic characteristics of Disphyma crassifolium and Suaeda maritima cultivated at six different salinities (35, 110, 200, 275, 350, and 465 mM NaCl), following the methodology outlined by Lima et al. [12]. In the referenced study, the authors assessed the same sensory attributes for Inula crithmoides and Mesembryanthemum nodiflorum. The sensory indicators for this study were established through preliminary discussions with a fine-dining chef with large experience using these plants in gourmet cuisine, referencing established descriptors for the evaluation of the halophyte plants. The selected attributes included flavour (salty and bitter taste), texture (crunchiness, juiciness, amount of fibre), physical parameters (appearance, plant length), and overall appreciation. Each attribute was precisely defined prior to the evaluation; for example, “crunchiness” referred to the perceived crispness during mastication, “juiciness” to the release of liquid upon biting, and “amount of fibre” to the perceived fibrousness or stringiness of the sample.

Quantification was performed using a four-point intensity scale specifically constructed for this study. For salty taste, bitter taste, and crunchiness, the scale ranged from “not enough” to “too much”; for the amount of fibre, from “non-existent” to “excessive”; for plant length, from “too short” to “too long”; and for appearance and overall appreciation, from “very bad” to “excellent”. These scoring principles were communicated in a detailed guideline document to all panellists before evaluation, ensuring a shared understanding of the criteria.

The tasting panel consisted of ten award-winning fine-dining chefs, with a mean professional experience of sixteen years. All chefs were selected based on their expertise in the use of halophyte plants in gourmet cuisine and their prior experience in sensory analysis. To enhance objectivity and reliability, a calibration session was conducted online before the formal evaluation. During this session, panellists discussed and aligned their understanding of each attribute and the scoring system, using reference samples where possible. This process also served to clarify terminology and ensure consistency in the application of the evaluation criteria according to QDA methodology requirements defined by Stone et al. [29].

To minimise individual preference bias and ensure impartiality, all samples were coded with random three-digit numbers and presented in a randomised order to each chef, ensuring a blind tasting. Chefs were instructed to refrain from discussing their assessments with others during the evaluation and were reminded to base their ratings solely on the defined criteria. Completed questionnaires were submitted online ensuring the confidentiality and independence of responses. The questionnaire itself was reviewed and pilot-tested by one of the chefs to confirm clarity and appropriateness of language. Given the high level of expertise of the panel and the calibration session, no further formal training was deemed necessary. These procedures ensured that the evaluation was rigorous and reproducible, with careful steps taken to control for potential biases and enhance the reliability and objectivity of the sensory data.

2.5. Statistical Analysis

Statistical analysis was performed using Statistica 7.0 software (Statsoft Inc., Tulsa, OK, USA). Results were expressed as mean ± standard error of the mean, and experiments were conducted at least in triplicate. Significant differences were assessed by analysis of variance (ANOVA) using the Tukey HSD (honestly significant differences) test, or Duncan’s new multiple range test when parameterisation of the data did not prevail.

3. Results and Discussion

3.1. Effects of Salinity on Productivity and Conductivity

Increasing cultivation salinity negatively impacted plant growth (Figure 2a). Similarly to what had been observed with M. nodiflorum and I. crithmoides [2], the species D. crassifolium exhibited a significant decrease (around 50%) in productivity at a salinity of 110 mmol L⁻¹, compared to samples grown at 35 mmol L⁻¹. At the highest salinity tested (465 mmol L⁻¹), productivity dropped to 95%. S. maritima displayed similar responses, although slightly less pronounced. Its productivity decreased by 40% with the increase from 35 to 110 mmol L⁻¹, and 86% at 465 mmol L⁻¹. These findings align with previous results by Aghaleh et al. [30] and Lima et al. [2], who observed reduced growth in Salicornia persica, S. europaea, and S. ramosissima at salinities exceeding 100 mmol L⁻¹. Similarly, Lima et al. [12] reported a 57% decrease in relative productivity for I. crithmoides when salinity was increased from 35 to 110 mmol L⁻¹. However, M. nodiflorum exhibited a contrasting behaviour, achieving maximum productivity between salinities of 35 and 100 mmol L⁻¹. These results indicate that the synergistic response between crop salinity and productivity is specific to each halophyte plant species. Nonetheless, the increase in salt concentration has undoubtedly resulted in a significant escalation in strategies employed to maintain ion and osmotic homeostasis, which, in turn, resulted in high energy expenditures, explaining the observed decline in productivity [31].

The conductivity of both species (Figure 2b) showed a slight increase from 110 mmol L⁻¹ with stabilisation at higher salinities (275 to 465 mmol L⁻¹), which shows an acclimation linked with the ability to regulate salt concentration in the tissues.

3.2. Microbial Quality

The effect of increasing salinity on the microbial quality of the halophytes Disphyma crassifolium, Inula crithmoides, Mesembryanthemum nodiflorum and Suaeda maritima are shown in

Table 1. Microbial quality of halophyte plants studied.

Halophyte Species	Microbial Groups (Log CFU g/plant −1)	Salinity (mmol L−1)
		35	200	465
D. crassifolium	Aerobic microorganisms at 30 °C	2.00 ± 0.06 aA	3.08 ± 0.05 bB	3.61 ± 0.05 cC
M. nodiflorum		2.98 ± 0.03 aB	3.26 ± 0.12 aB	3.06 ± 0.08 aB
I. crithmoides		4.54 ± 0.20 aC	5.18 ± 0.14 bC	5.38 ± 0.05 bD
S. maritima		2.65 ± 0.03 bB	2.48 ± 0.01 aA	2.60 ± 0.06 abA
D. crassifolium	Aerobic microorganisms at 6.5 °C (psychrotrophics)	2.00 ±0.01 aA	2.35 ± 0.49 aA	3.07 ± 0.16 aB
M. nodiflorum		2.35 ± 0.49 aA	2.15 ± 0.21 aA	2.97 ± 0.10 aB
I. crithmoides		2.35 ± 0.49 aA	2.50 ± 0.28 aA	2.15 ± 0.21 aA
S. maritima		2.48 ± 0.01 aA	2.80 ± 0.14 abA	3.14 ± 0.20 cB
D. crassifolium	Filamentous fungi	2.45 ± 0.21 aAB	3.80 ± 0.03 bA	4.38 ± 0.05 cC
M. nodiflorum		2.15 ± 0.21 aA	1.24 ± 1.75 aA	2.30 ± 0.43 aA
I. crithmoides		2.63 ± 0.21 aAB	3.00 ± 0.06 aA	3.11 ± 0.01 aAB
S. maritima		3.03 ± 0.11 aB	3.02 ± 0.09 aA	3.29 ± 0.02 aB
D. crassifolium	Yeasts	≤2	≤2	≤2
M. nodiflorum		≤2	≤2	≤2
I. crithmoides		≤2	≤2	≤2
S. maritima		≤2	≤2	≤2

Different uppercase letters in the same column indicate significant differences (p < 0.05) between halophyte species at each salinity, and different lowercase letters in the same line indicate significant differences (p < 0.05) between salinity levels for each species (≤2 Log CFU/g, indicates below the detection limit).

.

The increase in salinity of the nutritive solution was accompanied by a general rise in the microbial populations studied, namely the total aerobic and filamentous fungi on D. crassifolium and I. crithmoides and the psychrotrophic population on S. maritima (p < 0.05). The psychrotrophic population was less abundant when compared to the values of the mesophylls. This rise in microbial populations in conditions of salt stress was also observed in Salicornia ramosissima [2]. As mentioned above, the increase in the cultivation salinity of the nutritive solution during the growth of the four plants implies the adoption of ionic and osmotic homeostasis strategies, which are certainly different in the plants studied. D. crassifolium loses succulence and increases osmotic metabolite (e.g., proline) production due to salt increase [32]. Similarly, I. crithmoides increases the production of osmolytes, such as glycine betaine, and sugars (arabinose, fructose, and glucose). Still, it also activates a K⁺ transportation system, which may contribute to its salt tolerance [33]. M. nodiflorum, similarly to other Mesembryanthemum species, accumulates salt and water in epidermal bladder cells that act as a water storage reservoir, which helps them to maintain ion sequestration and homeostasis in the leaves [34]. Finally, S. maritima accumulates inorganic ions and proline to adapt to saline conditions, decreasing its transpiration rate and improving its water use efficiency [35,36]. These different responses to salt stress may result in different degrees of colonisation by microbial populations, as seen in this work.

The highest numbers of aerobic microorganisms were observed in I. crithmoides (4.54, 5.18, 5.38 Log CFU g⁻¹ in the 35, 200, and 465 mM of NaCl, respectively) and the lowest numbers of filamentous fungi on M. nodiflorum (2.15, 1.24, and 2.30 Log CFU g⁻¹ in the three concentrations, respectively). In the work of Lima et al. [12], M. nodiflorum extracts showed an increasing trend in phenolic production with salt stress, while I. crithmoides appeared to be more susceptible, losing the ability to produce phenolic compounds at salinities of 100 mmol L⁻¹ or higher. In addition, M. nodiflorum showed a significant increase in the antioxidant capacity observed up to a salinity of 275 mmol L⁻¹. The fact that M. nodiflorum presents higher phenolic content and higher antioxidant capacity may explain the inferior microbial colonisation observed when compared to I. crithmoides, namely regarding aerobic microorganisms at 30 °C and filamentous fungi, as phenolics are known to inhibit the growth of different bacteria and fungi [37].

Yeasts, E. coli, and S. aureus were not detected on these halophytes in any growing conditions. However, except for M. nodiflorum, plants cultivated at the highest salinity (465 mM) showed a level of filamentous fungi higher than 3 Log CFU g⁻¹. Nonetheless, regarding contamination with aerobes, the halophytes studied presented a satisfactory microbiological quality (<6 Log CFU g⁻¹) even when plants were cultivated at the highest salinity tested (465 mM). Overall, plants grown with low salinity levels (35 mM) revealed better microbial quality, being classified as satisfactory when considering aerobic microorganisms grown at 30 °C, and acceptable when considering fungi. Additionally, none of the samples studied contained E. coli, so it can be said that the halophytes analysed fulfilled the microbiological criteria of food hygiene according to the European Commission [38,39]. Results of the present study indicate that soilless cultures using low salinities produce plants adequate for consumption, considering their microbial quality. Antioxidative defence systems, especially non-enzymatic antioxidants (like flavonoids, ascorbate, glutathione, and tocopherols) but also enzymatic antioxidants (like superoxide dismutase, catalase, and glutathione reductase), are part of the mechanisms that enable halophytes to thrive in high salt conditions [3]. They may also be implicated in antimicrobial defence systems in some halophyte species/strains such as M. nodiflorum and S. maritima. On the other hand, different species of halophytic plants certainly develop distinct adaptive strategies depending on their gene pool and the environment in which they grow. In the case of D. crassifolium, hydroxybenzoic acids, which are antimicrobial and antifungal agents, were not detected, thus justifying the increase in the number of filamentous fungi, with increasing salinity in the plants studied (Table 1). In addition, this species has been described as having an efficient osmolyte accumulation system [40], and we hypothesise that these osmolytes constitute food reserves for some microbial groups (filamentous fungi). The present study’s results indicate that soilless cultures using low salinities produce plants adequate for consumption, considering their microbial quality. However, the growth of the microbial populations during storage was not evaluated, and thus, the shelf-life of plants at different temperatures, including refrigeration, was not evaluated.

3.3. Sensory Properties

To assess the commercial potential of these plants, an organoleptic evaluation was conducted by a trained sensory panel comprising highly acclaimed chefs, many of whom were awarded Michelin stars. This approach aimed to identify the plant with the most desirable sensory characteristics. Employing the quantitative descriptive analysis (QDA) method, the chefs defined the relevant sensory attributes for evaluation. Each chef received a set of plants grown at varying salinity levels and evaluated them based on predetermined parameters, which included saltiness, bitterness, crunchiness, juiciness, fibre content, visual appearance, and plant length. The responses were ranked and statistically analysed, with the results for species D. crassifolium and S. maritima presented in Figure 3. Results concerning the other two species were previously published in Lima et al. [12].

Despite a wide range in cultivation salinity (35–465 mmol L⁻¹), most sensory attributes of the analysed halophyte plant samples displayed subtle differences. This aligns with previous findings by Lima et al. [12] for M. nodiflorum and I. crithmoides grown under similar salinity variations, using the same sensory attributes, quantitative descriptive analysis (QDA) method, and trained tasters. As in Lima et al. [12], the most noticeable sensory differences between salt concentration in the cultivating medium were observed for prominent attributes like salty and bitter tastes in both species, although attributes like crunchiness and juiciness were also discriminant of salinity in S. maritima. The most pronounced sensory changes occurred in this species, with the plants grown at the lowest salinity tested scoring poorer for all attributes except juiciness. Notably, the “crunchiness” attribute had the lowest average score. These results are supported by other studies that showed that increasing cultivation salinity intensifies saltiness, while lower salinities enhance firmness but reduce juiciness and affect colour [12,41]. Moreover, Martins-Noguerol et al. [42] reported that higher salinity reduces the content of monounsaturated and polyunsaturated fatty acids and proteins, directly impacting the texture, liquid retention, taste, and juiciness of samples grown at the highest NaCl concentration (450 mmol L⁻¹). Common to both tested species was the fact that the intermediate salinities tested had the best scores in “Global Appreciation”. The scores of juiciness, crunchiness, and amount of fibre contributed the most to these results. The accumulation of osmolytes and succulence mechanisms to maintain the cell turgor pressure under higher saline conditions are strategies adopted by various halophytic plants for ion and osmotic homeostasis, explaining the general increasing juiciness and crunchiness attributes of plants used in the present work as salinity increases, particularly in D. crassifolium. Lima et al. [12] also found that I. crithmoides and M. nodiflorum grown at intermediate concentrations of NaCl performed better.

In summary, lower salinities applied in soilless cultivation systems provide a more balanced organoleptic profile for halophyte species.

4. Conclusions

This study demonstrated that soilless cultivation of Disphyma crassifolium, Inula crithmoides, Mesembryanthemum nodiflorum, and Suaeda maritima ensures microbiological quality (<6 Log CFU/g aerobes; absence of E. coli, staphylococci, and yeasts) at salinities up to 465 mM, in accordance with EU food hygiene standards. However, filamentous fungi exceeded 3 Log CFU/g in most species at 465 mM, highlighting salinity-dependent microbial risks. Furthermore, the results indicate that intermediate salinities (200–350 mM NaCl) optimised the sensory appeal of D. crassifolium and S. maritima, which were preferred by panellists due to attributes such as texture and flavour, while also maintaining microbial quality. This dual focus on safety and sensory preference establishes 200–350 mM as the ideal range for commercial production, offering a model for scaling up halophyte agriculture in saline environments without compromising food safety or consumer acceptance. [38,39]