Milk heat treatment affects microbial characteristics of cows’ and goats’ “Jben” traditional fresh cheeses

Analysis of the bacterial diversity in Moroccan Jben cheese using TTGE, DGGE, and 16S rRNA sequencing

This research investigated the physicochemical, microbiological, and bacterial diversity of Jben cheese, a popular artisanal variety in Morocco. The bacterial diversity was explored using culture-independent methods, including temporal temperature gel electrophoresis (TTGE), denaturing gradient gel electrophoresis (DGGE), and high-throughput sequencing (HTS). Significant intra-sample differences were observed for most physicochemical parameters within each milk type, while inter-sample differences occurred between cow and goat cheeses for dry matter and ash. Jben cheese exhibited distinct characteristics, with low pH values of 3.96, 4.16, and 4.18 for cow, goat, and mixed cheeses, respectively. Goat cheeses had higher fat (49.23 g/100 g), ash (1.91 g/100 g), and dry matter (36.39 g/100 g) than cow cheeses. All cheeses displayed high microbial counts, with a notable prevalence of the lactic acid bacteria (LAB) group, averaging 8.80 ± 0.92 log CFU/g. Jben cheese also displayed high contamination levels with total coliforms, faecal coliforms, yeast, and molds. Fatty acid profiling revealed fraudulent practices in Jben cheese marketing, with cow or mixed cheeses sold as goat cheese, as proven by low capric acid concentration. HTS analysis of Jben cheese identified ten genera and twenty-four species, highlighting Lactococcus lactis as predominant. TTGE and DGGE confirmed the presence of L. lactis but failed to provide the detailed profile achieved through HTS analysis. HTS has been demonstrated to be more reliable, whereas TTGE/DGGE methods, though informative, were more time-consuming and less reliable. Despite limitations, the combined use of TTGE, DGGE, and HTS provided a comprehensive view of indigenous bacterial communities in Jben cheese, identifying L. lactis as the main species.

In vitro assessment of biofunctional properties of Lactiplantibacillus plantarum strain Jb21-11 and the characterization of its exopolysaccharide

ABSTACT

The microbiota of traditional food provides a rich reservoir of biodiversity to find new strains with interesting features for novel functional food formulation. Therefore, this study aimed to investigate the biofunctional potential of the lactic acid bacteria (LAB) strain Jb21-11 isolated from Jben, a traditional Algerian fresh cheese. This isolate was selected out of a collection of 154 LAB based on its exopolysaccharide (EPS) phenotype and was preliminarily identified by polyphasic characterization as Lactiplantibacillus plantarum (previously known as Lactobacillus plantarum) and its biofunctional properties were then assessed in vitro. The tested strain demonstrated good resistance to gastric juice, acidity around pH 2, and 2% (v/v) bile salts, which are important characteristics for potential biofunctional LAB candidates. It also showed a good production of ropy EPS with 674 mg/L on MRS medium. However, this ability appears to compromise the adhesion of the strain to Caco-2 cells (less than 1%), which according to our results, seems not to be related to autoaggregation and hydrophobicity (44.88 ± 0.028% and 16.59 ± 0.012%). Furthermore, promising antimicrobial activity against three pathogenic bacteria (Escherichia coli, Staphylococcus aureus, and Salmonella) was detected probably due to antimicrobial metabolites excreted during fermentation process into the medium. Moreover, the strain L. plantarum Jb21-11 displayed a therapeutic functionality with both anti-inflammatory and immunomodulatory action using RAW 264.7 cells. The chemical features of the novel ropy Jb21-11-EPS were also investigated revealing the presence of three monosaccharides, namely, mannose, galactose, and glucose, with a molar ratio of 5.42:1.00:4.52 linked together by α- and β-glycosidic bonds, presenting a relatively high molecular weight of 1.08 × 105 Da of interest for a texturing potential. Therefore, the new producing EPS strain Jb21-11 is a promising candidate for use as an adjunct culture for improving the texture of functional food.

Tracking microbial quality, safety and environmental contamination sources in artisanal goat cheesemaking factories

A harmonised microbiological survey was performed in two artisanal factories of raw goat milk cheeses (A and B) located in the Andalusian region (Spain). A total of 165 different control points or samples (raw materials, final products, food-contact surfaces [FCS], and air) were examined as microbial and pathogen sources of contamination of artisanal goat raw milk cheeses. For raw milk samples analysed from both producers, the concentrations of aerobic-mesophilic bacteria (AMB), total coliforms, coagulase-positive Staphylococcus spp. (CPS), lactic-acid bacteria (LAB) and moulds and yeasts ranged between 3.48 and 8.59, 2.45-5.48, 3.42-4.81, 4.99-8.59 and 3.35-6.85 log cfu/mL respectively. For the same microbial groups, the analysis of raw milk cheeses revealed concentrations ranging from 7.82 to 8.88, 2.00-6.82, 2.00-5.28, 8.11-9.57 and 2.00-5.76 log cfu/g, respectively. Although the raw material analysed from producer A presented higher microbial loads and between-batch variability, it was B the producer with the most loaded final products. Regarding the microbial air quality, the fermentation area, storage room, milk reception and packaging room were the most AMB loaded places, while the ripening chamber was the area with higher fungal loads in bioareosol from both producers. Conveyor belts, cutting machine, storage boxes and brine tank were highlighted as the most contaminated FCS evaluated. Staphylococcus aureus was the only pathogen detected within the set of 51 isolates from samples as revealed by MALDI-TOF and molecular PCR, with a prevalence of 12.5% for samples from the producer B. The public health risk attributed to the consumption of artisanal goat cheese should not be neglected, and may consider the whole cheesemaking processing chain, from microbiological quality of raw milk to the ready-to-eat final product, especially concerning the presence of S. aureus.

The influence of the texture and color of goat’s salad cheese on the emotional reactions of consumers compared to cow’s milk cheese and Feta cheese

In this study, the sensory and mechanical aspects of the texture of goat’s milk salad cheese were correlated with the emotional profiles of consumers. Using descriptive sensory analysis and instrumental assessment, the texture profile of goat’s milk salad cheese was compared to cow’s milk salad cheese and Feta cheese. Texture measurements confirmed that goat’s cheese compared to cow’s cheese had more softness and less hardness, and Feta cheese had the highest whiteness index compared to the other cheeses. Goat’s milk salad cheese was much less acceptable to consumers compared to cow’s milk cheese and Feta cheese. Consumers also indicated that the hardness of goat’s cheese was lower than that of cow’s cheese and Feta cheese. A reduction in “stickiness” in comparison with cow’s cheese was also reported; however, it was much higher than that for Feta cheese. The “fracturability” and “graininess” of goat’s cheese was similar to cow’s cheese. Emotional profile analysis showed that goat’s cheese evokes mainly negative emotions. Consumers indicated only one positive emotion in the case of this cheese, which was “healthy”. The most frequently mentioned emotions after the consumption of goat’s cheese were “upset”, “disgusted” and “worried”. Many consumers also indicated “disappointed” and “angry”, which did not occur after the consumption of cow’s cheese. This research shows how important it is to combine several analyses and techniques when evaluating dairy products, including salad cheeses. It is also important that consumer research is enriched by emotional profiling.

Graphical abstract

Development of a Novel Flavored Goat Cheese with Gentiana lutea Rhizomes

Gentiana lutea rhizomes, generally used as a bittering agent in food, were harvested from two geographical sites (Massif Central: MC and Jura: J) to evaluate their potential use in the flavoring step during goat cheesemaking. Gentian flavored goat cheeses (MCGC and JGC) were elaborated by a one-night immersion of unflavored goat cheeses (CGC) into gentian-infused whey. The impregnation of gentian in goat cheeses was evaluated by chemical and sensory analysis. The chemical composition of cheeses was analyzed by HS-SPME-GC-MS (Head-Space-Solid Phase MicroExtraction-Gas Chromatography-Mass Spectrometry) for volatile compounds (alcohols, ketones, aldehydes, esters, alkenes, alkanes, acids, terpenes) and UHPLC-DAD (Ultra High-Performance Liquid Chromatography-Diode Array Detector) for gentian bitter compounds (seco-iridoids). The sensory analysis consisted of a bitterness rating and a free description of cheeses by 17 trained panelists. Results of the study highlighted that unflavored goat cheeses presented higher unpleasant notes (goaty and lactic whey) and higher amounts of hexanoic acid and toluene compared to gentian flavored goat cheeses. The bitterness of gentian flavored goat cheeses was higher compared to unflavored cheeses and could be explained by loganic acid transfer from yellow gentian to flavored cheeses. Other free descriptors of gentian flavored goat cheeses revealed more complex notes (herbal, vegetal, floral, sweet, spicy and creamy) and higher relative amounts of volatile compounds such as 3-methyl butanoic acid, 2-methyl propanoic acid, 4-methyl decane, 2,3-butanediol, ethanol, diacetyl, methyl acetate and 2-phenylethyl acetate, compared to unflavored cheeses. Phenylethyl acetate was the only volatile compound that enabled differentiation of gentian origin on gentian flavored goat cheeses. Gentian rhizomes could be considered a promising flavoring agent contributing to the olfactive and gustative complexity of flavored goat cheeses and the reduction of their goaty perceptions.

An Insight into Goat Cheese: The Tales of Artisanal and Industrial Gidotyri Microbiota

The purpose of this study was to determine for the first time the microbiota in artisanal-type and industrial-type Gidotyri cheeses and investigate the influence of the cheese-making practices on their composition using culture-independent techniques. The microbiota present in artisanal with commercial starters (Artisanal_CS, n = 15), artisanal with in-house starters (Artisanal_IHS, n = 10) and industrial (Ind., n = 9) Gidotyri cheese samples were analyzed using a targeted metagenomic approach (16S rRNA gene). The Ind. Gidotyri cheese microbiota were less complex, dominated by the Streptococcaceae family (91%) that was more abundant compared to the artisanal Gidotyri cheeses (p < 0.05). Artisanal cheeses were more diverse compositionally with specific bacterial species being prevalent to each subtype. Particularly, Loigolactobacillus coryniformis (OTU 175), Secundilactobacillus malefermentans (OTU 48), and Streptococcus parauberis (OTU 50) were more prevalent in Artisanal_IHS cheeses compared to Artisanal_CS (p ≤ 0.001) and Ind. (p < 0.01) Gidotyri cheeses. Carnobacterium maltaromaticum (OTU 23) and Enterobacter hormaechei subsp. hoffmannii (OTU 268) were more prevalent in Artisanal_CS cheeses compared to Artisanal_IHS cheeses (p < 0.05) and Ind. cheeses (p < 0.05). Hafnia alvei (OTU 13) and Acinetobacter colistiniresistens (OTU 111) tended to be more prevalent in Artisanal_CS compared to the other two cheese groups (p < 0.10). In conclusion, higher microbial diversity was observed in the artisanal-type Gidotyri cheeses, with possible bacterial markers specific to each subtype identified with potential application to traceability of the manufacturing processes’ authenticity and cheese quality.

Traditional Fermented Dairy Products in Southern Mediterranean Countries: From Tradition to Innovation

Fermented dairy products have been essential elements in the diet of Southern Mediterranean countries for centuries. This review aims to provide an overview of the traditional fermented products in Southern Mediterranean countries, with a focus on fermented dairy products, and to discuss innovative strategies to make improved versions of these traditional products. A large variety of fermented dairy products were reviewed, showing high diversity, depending on the used raw materials, starter cultures, and preparation procedures. Traditionally, dairy products were fermented using spontaneous fermentation, back-slopping, and/or the addition of rennet. Compared with commercial products, traditional products are characterized by peculiar organoleptic features owing to the indigenous microflora. The main limitation of traditional products is preservation as most products were consumed fresh. In addition to drying, brine or oil was used to extend the product shelf life but resulted in high salt/fat products. Several studies suggested alternative ingredients/processing to make revised products with new flavors, improved nutritional quality, and a longer shelf life. There is still plenty of room for more research to obtain a better understanding of the indigenous microflora and on quality improvement and standardization to reach a wider market.

Different Ultrasound Exposure Times Influence the Physicochemical and Microbial Quality Properties in Probiotic Goat Milk Yogurt

Despite goat milk having health benefits over cow milk, goat milk yogurt (GY) presents low consistency and viscosity, which reduces its overall acceptability by the consumer. Thus, new innovative methods can be an alternative to improve the quality of GY. Hence, this study aimed to investigate the effect of ultrasound (US) treatment with different sonication times on quality parameters of probiotic GY during refrigerated storage. US treatment was conducted at 20 KHz for 3, 6, and 9 min in yogurt. Lactobacillus bulgaricus and Lactobacillus acidophilus LA-5 were sensitive to US treatment, presenting a decrease in the yogurts stocked. This loss of viability led to reduced post-acidification due to smaller lactose metabolization in yogurt samples submitted to the US. Among tested treatments, the application of 6 min enhanced the apparent viscosity and consistency index of GY yogurts. In addition, this time also reduced tyramine and total biogenic amine (BAs) content. These findings suggest that 6 min of sonication is a promising way to improve the rheological properties and reduce the acidity and BAs content in GY. Further studies should be performed to optimize the US setting conditions to preserve the probiotic culture viability in yogurts.