Phenotypic, Technological, Safety, and Genomic Profiles of Gamma-Aminobutyric Acid-Producing Lactococcus lactis and Streptococcus thermophilus Strains Isolated from Cow's Milk.

Gamma-aminobutyric acid (GABA)-producing lactic acid bacteria (LAB) can be used as starters in the development of GABA-enriched functional fermented foods. In this work, four GABA-producing strains each of Lactococcus lactis and Streptococcus thermophilus species were isolated from cow's milk, and their phenotypic, technological, and safety profiles determined. Genome analysis provided genetic support for the majority of the analyzed traits, namely, GABA production, growth in milk, and the absence of genes of concern. The operon harboring the glutamate decarboxylase gene (gadB) was chromosomally encoded in all strains and showed the same gene content and gene order as those reported, respectively, for L. lactis and S. thermophilus. In the latter species, the operon was flanked (as in most strains of this species) by complete or truncated copies of insertion sequences (IS), suggesting recent acquisition through horizontal gene transfer. The genomes of three L. lactis and two S. thermophilus strains showed a gene encoding a caseinolytic proteinase (PrtP in L. lactis and PrtS in S. thermophilus). Of these, all but one grew in milk, forming a coagulum of good appearance and an appealing acidic flavor and taste. They also produced GABA in milk supplemented with monosodium glutamate. Two L. lactis strains were identified as belonging to the biovar. diacetylactis, utilized citrate from milk, and produced significant amounts of acetoin. None of the strains showed any noticeable antibiotic resistance, nor did their genomes harbor transferable antibiotic resistance genes or genes involved in toxicity, virulence, or pathogenicity. Altogether these results suggest that all eight strains may be considered candidates for use as starters or components of mixed LAB cultures for the manufacture of GABA-enriched fermented dairy products.

Effect of industrial wastewater treatment system upgrade on the composition of emitted odorants and volatile organic compounds from a cheese production facility.

This study investigates the rarely studied volatile organic compound emissions from a cheese production facility and the impact of its wastewater treatment system upgrade on the composition of emitted odorants. Wastewater grab samples were collected from six separate wastewater channels before (2019) and after (2021) the system upgrade and analyzed for volatile organic compounds, pH, total dissolved solids, and electrical conductivity. Results showed that the channel from hard cheese production in 2021 had the highest number of volatile organic compounds (35), followed by the fresh cheese production channel (22). Following the industrial wastewater treatment system upgrade, a mineral oil contamination occurred; however, the number of odorants with nasal impact frequency (NIF) ≥ 0.5 in the effluent decreased from 11 to 5. 2-Propenoic acid butyl ester (NIF 0.75) stood out as the most prominent compound, described as fruity, waxy, or green. After the industrial wastewater treatment system upgrades, we observed a decrease in the number of odorants. However other measures must be taken to ensure proper wastewater processing. PRACTITIONER POINTS: More than 60 VOCs were identified in 6 channels from the cheese production facility.15 odorants in cheese production wastewater were detected by SPME-GC-MS/O. The most potent odorants before and after the system upgrade were 1-octen-3-ol and 2-propenoic acid butyl ester, respectively. The upgrades of the industrial wastewater treatment system had a positive impact on reducing the number of odorants and their odor intensity.

Elimination of detached Listeria monocytogenes from the biofilm on stainless steel surfaces during milk and cheese processing using natural plant extracts.

Bacterial cells can form biofilm on food contact surfaces, becoming a source of food contamination with profound health implications. The current study aimed to determine some Egyptian medicinal plants antibacterial and antibiofilm effects against foodborne bacterial strains in milk plants. Results indicated that four ethanolic plant extracts, Cinnamon (Cinnamomum verum), Chamomile (Matricaria chamomilla), Marigold (Calendula officinalis), and Sage (Salvia officinalis), had antibacterial (12.0-26.5 mm of inhibition zone diameter) and antibiofilm (10-99%) activities against Staphylococcus aureus, Bacillus cereus, Listeria monocytogenes and Salmonella Typhimurium. The tested extracts had minimum inhibitory concentration values between 0.14 and 2.50 mg/ml and minimum bactericidal concentration values between 0.14 and 12.50 mg/ml. L. monocytogenes was more sensitive for all tested ethanolic extracts; Sage and Cinnamon showed a bacteriocidal effect, while Chamomile and Marigold were bacteriostatic. The ethanolic extracts mixture from Chamomile, Sage, and Cinnamon was chosen for its antibiofilm activity against L. monocytogenes using L-optimal mixture design. Gas chromatography and mass spectrometry analysis showed that this mixture contained 12 chemical compounds, where 2-Propenal,3-phenyl- had the maximum area % (34.82%). At concentrations up to 500 µg/ml, it had no cytotoxicity in the normal Vero cell line, and the IC50 value was 671.76 ± 9.03 µg/ml. Also, this mixture showed the most significant antibacterial effect against detached L. monocytogenes cells from formed biofilm in stainless steel milk tanks. At the same time, white soft cheese fortified with this mixture was significantly accepted overall for the panelist (92.2 ± 2.7) than other cheese samples, including the control group.

Comprehensive metabolic profiling of Geotrichum candidum and comparison with Saccharomyces cerevisiae.

Geotrichum candidum is a dimorphic yeast used in cheese processing. To our knowledge, no major metabolites have been identified to date in G. candidum except for some amino acid and fatty acid metabolites. This has limited research on the commercial use of G. candidum. In this study, we aimed to analyze temporal changes in the intra- and extra-cellular metabolites of G. candidum and Saccharomyces cerevisiae cultured in YM medium as reference. As a result of metabolite analysis, it was observed that G. candidum tends to accumulate　pentose phosphate pathway compounds, which are involved in nucleic acid synthesis, after 48 h of cultivation when compared to S. cerevisiae. In addition, G. candidum accumulated higher amounts of the antioxidant glutathione in the medium than did S. cerevisiae. In addition, G. candidum accumulated large amounts of B vitamins such as pantothenic acid and nicotinic acid in the medium. Finally, we examined the potential of G. candidum as a host for the production of useful compounds such as pantothenic acid. When cultured in medium supplemented with the pantothenic acid precursor ß-alanine, G. candidum produced 12-fold higher amounts of pantothenic acid (30 µM) than that by S. cerevisiae. This study indicates that G. candidum accumulates various useful compounds that are dissimilar to those produced by S. cerevisiae. Furthermore, G. candidum has the potential to produce useful chemicals under appropriate culture conditions.

Chitosan film with pineapple peel extract in the extension of shelf life of Indian cottage cheese: Release kinetics and bio-accessibility studies.

Pineapple-peel-based chitosan film was employed to extend the shelf life of Indian Cottage Cheese, commonly termed "paneer" in the Indian subcontinent. Pineapple peel extracts (PPE) at 3 different concentrations (1-3 %) were incorporated into the chitosan matrix. In comparison to control samples (unpacked paneer), packaged paneer samples exhibited reduced weight loss, lipid peroxidation, and pH changes. The microbiological shelf life of paneer got extended till 9th day at 4 °C when packaged in chitosan-PPE films. Korsmeyer-Peppas's model suggested that the release of polyphenols from the chitosan-PPE film followed Fickian diffusion. As per sensory evaluation on a 9-point hedonic scale, packaged paneer samples were superior in juiciness, texture, color, flavor, and overall acceptability compared to unpackaged paneer samples. As compared to the control sample (CS), the overall acceptance was higher for the film with 1 % pineapple peel extract (CS PPE 1), followed by films with 2 % and 3 % pineapple peel extracts (CS-PPE 2 and CS-PPE 3). The bio-accessibility study utilized the dynamic gastric model to simulate digestion in the upper gastrointestinal tract and revealed 40-60 % recovery rate of polyphenols from the chitosan-pineapple peel film.

Limited Cheese Intake Paradigm Replaces Patterns of Behavioral Disorders in Experimental PTSD: Focus on Resveratrol Supplementation.

Currently, the efficacy of drug therapy for post-traumatic stress disorder or PTSD leaves much to be desired, making nutraceutical support a promising avenue for treatment. Recent research has identified the protective effects of resveratrol in PTSD. Here, we tested the behavioral and neurobiological effects of combining cheese consumption with resveratrol supplements in an experimental PTSD model. Using the elevated plus maze test, we observed that cheese intake resulted in a shift from anxiety-like behavior to depressive behavior, evident in increased freezing acts. However, no significant changes in the anxiety index value were observed. Interestingly, supplementation with cheese and resveratrol only led to the elimination of freezing behavior in half of the PTSD rats. We further segregated the rats into two groups based on freezing behavior: Freezing+ and Freezing0 phenotypes. Resveratrol ameliorated the abnormalities in Monoamine Oxidize -A and Brain-Derived Neurotrophic Factor gene expression in the hippocampus, but only in the Freezing0 rats. Moreover, a negative correlation was found between the number of freezing acts and the levels of Monoamine Oxidize-A and Brain-Derived Neurotrophic Factor mRNAs in the hippocampus. The study results show promise for resveratrol supplementation in PTSD treatment. Further research is warranted to better understand the underlying mechanisms and optimize the potential benefits of resveratrol supplementation for PTSD.

Control of Listeria monocytogenes in a fresh cheese using aromatic and medicinal plants and enterocin: a comparative study.

The aim of this study was to investigate the effectiveness of essential oils (EOs) or crude extracts (CEs) of eight aromatic and medicinal plants (AMPs) and its association with enterocin OS1 on Listeria monocytogenes and food spoilage bacteria in Moroccan fresh cheese. The cheese batches were treated with EO of Rosmarinus officinalis, Thymus vulgaris, Syzygium aromaticum, Laurus nobilis, Allium sativum, Eucalyptus globulus, or CE of Crocus sativus and Carthamus tinctorius, and/or enterocin OS1, and stored for 15 days at 8°C. The data were subjected to correlations analysis, variance analysis, and principal components analysis. Results clearly showed a positive correlation between L. monocytogenes reduction and storage time. Moreover, reduction on Listeria counts induced by Allium-EO and Eucalyptus-EO reached 2.68 and 1.93 Log CFU/g with respect to untreated samples after 15 days, respectively. Similarly, enterocin OS1 alone has significantly reduced the L. monocytogenes population with 1.46 Log CFU/g. The most promising result was the synergy observed between many AMPs and enterocin. Indeed, treatments with Eucalyptus-EO + OS1 and Crocus-CE + OS1 decreased the Listeria population to undetectable after only 2 days and throughout the storage period. These findings suggest a promising application/use of this natural combination, which preserves the safety and long-lasting conservation of fresh cheese.

Optimization of caseinolytic and coagulating activities of Solanum tuberosum rennets for cheese making.

BACKGROUND: In recent years, the rising global demand for cheese, the high cost and limited supply of calf rennet, and consumer choices have increased research into new alternatives to animal or recombinant chymosins for cheese making. Plant proteases with caseinolytic activity (CA) and milk-clotting activity (MCA) have been proposed as alternatives for milk clotting to obtain artisanal cheeses with new organoleptic properties. They have been named vegetable rennets (vrennets). The aim of this study was to evaluate the performance of two Solanum tuberosum aspartic proteases (StAP1 and StAP3) as vrennets for cheese making and to obtain a statistical model that could predict and optimize their enzymatic activity. RESULTS: To optimize the CA and MCA activities, a response surface methodology was used. Maximum values of CA and MCA for both enzymes were found at pH 5.0 and 30-35 °C. Analysis of the degradation of casein subunits showed that it is possible to tune the specificity of both enzymes by changing the pH. At pH 6.5, the αS - and ß- subunit degradation is reduced while conserving a significant MCA. CONCLUSION: The statistical models obtained in this work showed that StAP1 and StAP3 exert CA and MCA under pH and temperature conditions compatible with those used for cheese making. The casein subunit degradation percentages obtained also allowed us to select the best conditions for the degradation of the κ-casein subunit by StAPs. These results suggest that StAP1 and StAP3 are good candidates as vrennets for artisan cheese making. © 2023 Society of Chemical Industry.

Portable near-infrared (NIR) spectrometer and chemometrics for rapid identification of butter cheese adulteration.

Artisanal cheeses are highly valued around the world for their distinct sensory characteristics, thus being prone to adulteration by substituting authentic material for cheaper products, such as vegetable oil. In this work, we developed a method based on a portable NIR spectrometer as a non-destructive and low-cost alternative to identify adulteration in butter cheese. Dataset consisted of authentic and intentionally adulterated cheeses in the laboratory and commercial cheeses, which were identified as authentic and adulterated with vegetable oil after analysis of the fatty acid profile. PLS-DA classification models identified adulterated samples with an accuracy of 94.44%. PLS prediction models showed excellent performance (RPD > 3.0) to predict the adulterant level. These results demonstrate that NIR spectra can be used to identify the replacement of authentic fat by soybean oil in butter cheese and that the developed models can be used to identify adulteration in external samples with good performance.

Mango (Mangifera indica L.) young leaf extract as brine additive to improve the functional properties of mozzarella cheese.

Mango (Mangifera indica L.) has been an important plant in traditional medicine for over 4000 years, probably because of its remarkable antioxidant activity. In this study, an aqueous extract from mango red leaves (M-RLE) was evaluated for its polyphenol profile and antioxidant activity. The extract was used as brine replacement (at 5%, 10% and 20% v/v) in fresh mozzarella cheese for improving its functional properties. During storage (12 d at 4 ± °C), compositional analysis performed on mozzarella has shown a progressive increase of iriflophenone 3-C-glucoside and mangiferin, the compounds most present in the extract, with a noticeable preference for the benzophenone. At the same time, the antioxidant activity of mozzarella peaked at 12 d of storage, suggesting a binding action of that matrix for the M-RLE bioactive compounds. Moreover, the use of the M-RLE has not negatively influenced the Lactobacillus spp. population of mozzarella, even at the highest concentration.

Valorisation of Whey Permeate in Sequential Bioprocesses towards Value-Added Products-Optimisation of Biphasic and Classical Batch Cultures of Kluyveromyces marxianus.

Whey permeate is categorised as hazardous wastewater for aquatic environments, mainly due to its high lactose content. Therefore, it must be valorised before being released into the environment. One pathway for whey permeate management is its use in biotechnological processes. Herein, we present roads for whey permeate valorisation with the K. marxianus WUT240 strain. The established technology is based on two bioprocesses. During first, 2.5 g/L 2-phenylethanol and fermented plant oils enriched with different flavourings are obtained after 48 h biphasic cultures at 30 °C. The second process leads to a maximum of 75 g ethanol/L (YP/S = 0.53 g/g) after 96 h at 30 °C. Moreover, established whey permeate valorisation pathways reduced its biochemical oxygen demand and chemical oxygen demand values by 12- to 3-fold, respectively. Together, the present study reports a complete, effective, and environmentally friendly whey permeate management strategy while simultaneously enabling the acquisition of valuable compounds with substantial application potential.

Effect of Microencapsulated Basil Extract on Cream Cheese Quality and Stability.

The antimicrobial and antioxidant effects of plant extracts are well known, but their use is limited because they affect the physicochemical and sensory characteristics of products. Encapsulation presents an option to limit or prevent these changes. The paper presents the composition of individual polyphenols (HPLC-DAD-ESI-MS) from basil (Ocimum basilicum L.) extracts (BE), and their antioxidant activity and inhibitory effects against strains of Staphylococcus aureus, Geobacillus stearothermophilus, Bacillus cereus, Candida albicans, Enterococcus faecalis, Escherichia coli, and Salmonella Abony. The BE was encapsulated in sodium alginate (Alg) using the drop technique. The encapsulation efficiency of microencapsulated basil extract (MBE) was 78.59 ± 0.01%. SEM and FTIR analyses demonstrated the morphological aspect of the microcapsules and the existence of weak physical interactions between the components. Sensory, physicochemical and textural properties of MBE-fortified cream cheese were evaluated over a 28-day storage time at 4 °C. In the optimal concentration range of 0.6-0.9% (w/w) MBE, we determined the inhibition of the post-fermentation process and the improvement in the degree of water retention. This led to the improvement of the textural parameters of the cream cheese, contributing to the extension of the shelf life of the product by 7 days.

Antimicrobial potential of kombucha fresh cheese with the addition of sage (Salvia officinalis L.) and its preparations.

One of the main challenges in fresh cheese technology is its rather limited shelf life. Prolongation of the shelf life of fresh cheese has been the focus of numerous research studies and different strategies have been thus used. One of the strategies that could prolong the shelf life of fresh cheese, as well as increase its quality is the application of different starter cultures. As the antimicrobial capacity of sage (Salvia officinalis) has been proven, the possibility of reusing its by-product obtained from a tea factory could be a significant step towards the retention of environmental equilibrium and simultaneous production of food with additional functional value. Therefore, the aim of our research was to examine the antimicrobial potential of kombucha fresh cheese with the addition of ground herbal sage, sage essential oil and sage supercritical fluid extract, and compare it with fresh cheese obtained from a commercial starter culture. In order to examine the antimicrobial activity of kombucha fresh cheese produced with the addition of sage preparations, the produced samples were artificially contaminated with common foodborne contaminants: Listeria monocytogenes, Escherichia coli and Staphylococcus aureus. The obtained results revealed that the addition of sage essential oil and herbal ground sage increased the antimicrobial activity during the 30 days of storage against E. coli in kombucha fresh cheese (decrease of 2.9 and 2.5 log CFU g-1, respectively). Implementation of sage significantly increased the antimicrobial activity of the fresh cheese produced with a commercial XPL-1 starter culture against L. monocytogenes (essential oil - 0.9 log CFU g-1 and ground sage - 1.2 log CFU g-1). In the XPL-1 sample, the growth of S. aureus was inhibited by the addition of ground sage - a decrease of 1.4 log CFU g-1. Analysis of the total phenols revealed their 5-fold higher content in the kombucha fresh cheeses compared to the samples obtained by the XPL-1 starter culture. These results correlate with the higher antimicrobial activity of the kombucha fresh cheese samples compared to the XPL-1 samples. According to our results, industrial waste, obtained as a by-product in sage (Salvia officinalis) filter tea production, can be efficiently used in fresh cheese technology in order to increase the antimicrobial activity against L. monocytogenes, E. coli and S. aureus.

Effect of reduced-calcium and high-calcium cheddar cheese consumption on the excretion of faecal fat: a 2-week cross-over dietary intervention study.

PURPOSE: Studies show that dairy fat consumed in the form of cheese reduce LDL-cholesterol concentration (LDL-c) compared to butter and mechanistic suggestions include the calcium content of cheese leading to enhanced faecal fat excretion. The aim of this study was to test the effect of varying the calcium content within a cheese, on faecal fat excretion as a primary outcome, and blood lipid markers, fasting glucose and calcium excretion as secondary outcomes. METHODS: 7 healthy males (BMI 18-25) participated in this randomized, cross-over control intervention, of 3 × 2 week periods. Diets contained 240 g/day cheese; a High Calcium Cheese (HCC) diet, a Reduced Calcium Cheese (RCC) diet, and a control arm: Reduced Calcium Cheese + CaCO3 Supplement (RCC + Supp) diet. Diets differed in calcium content and form but were otherwise controlled for energy and key macronutrients. Blood and 5-day faecal samples were collected. RESULTS: There was no significant difference in faecal fat excretion (g/day) between the diets (P = 0.066). Percent fat of faecel excretion was higher after RCC + Supp (P = 0.016). None of the individual fatty acids were different. Fasting LDL-c was significantly lower following the HCC diet vs. the other arms (P = 0.002). Faecal Ca was different across all diets (P = 0.001), lowest after RCC, and greatest after RCC + Supp. No differences were observed for fasting blood parameters or changes in anthropometry. CONCLUSION: Varying the calcium content within a cheese matrix significantly affected fasting LDL-c values. Results did not support higher faecal fat excretion as an underlying mechanism, but the high attrition rate was a limitation. Trial registerer Trial Registered at ISRCTN.org, registration number ISRCTN11663659 on 12.07.2022. Retrospectively registered.

Detection of Vegetable Oil Adulteration in Pre-Grated Bovine Hard Cheeses via 1H NMR Spectroscopy.

Adulteration of food products is a widespread problem of great concern to society and dairy products are no exception to this. Due to new methods of adulteration being devised in order to circumvent existing detection methods, new detection methods must be developed to counter fraud. Bovine hard cheeses such as Asiago, Parmesan, and Romano are widely sold and consumed in pre-grated form for convenience. Due to being processed products, there is ample opportunity for the introduction of inexpensive adulterants and as such, there is concern regarding the authenticity of these products. An analytical method was developed using a simple organic extraction to verify the authenticity of bovine hard cheese products by examining the lipid profile of these cheeses via proton Nuclear Magnetic Resonance (NMR) spectroscopy. In this study, 52 samples of pre-grated hard cheese were analyzed as a market survey and a significant number of these samples were found to be adulterated with vegetable oils. This method is well suited to high throughput analysis of these products and relies on ratiometrics of the lipids in the samples themselves. Genuine cheeses were found to have a very consistent lipid profile from sample to sample, improving the power of this approach to detect vegetable oil adulteration. The method is purely ratiometric with no need for internal or external references, reducing sample preparation time and reducing the potential for the introduction of error.

Development of Innovative Vitamin D Enrichment Designs for Two Typical Italian Fresh Cheeses: Burrata and Giuncata.

The aim of this research was to develop innovative cheeses fortified with vitamin D3 (VD3). Formulation studies and analyses of textural properties and chemicals were carried out for these developments. Two traditional Italian varieties of cheese (giuncata and burrata) were studied. For giuncata, the fortification of milk for cheese production provided a VD3 retention level of 43.9 ± 0.6% in the food matrix. For burrata, the VD3 ingredient was incorporated into the creamy inner part after mixing, maintaining the textural quality of the product (adhesiveness 4.3 ± 0.4 J × 10-3; firmness 0.7 ± 0.0 N; and cohesiveness 0.8 ± 0.2). The optimized enrichment designs allowed to obtain homogenous contents of VD3 during the production of giuncata (0.48 ± 0.01 µg/g) and burrata cheeses (0.32 ± 0.02 µg/g). Moreover, analyses revealed the high stability of VD3 during the storage of the two fortified cheese types (2 weeks, 4 °C). These fortification designs could be implemented at an industrial scale to obtain new cheese types enriched in VD3 and thus contribute to the reduction in VD deficiency prevalence.

Use of food and food-derived products in the treatment of gastritis: A systematic review.

Gastritis is the acute or chronic inflammation of gastric mucosa and is triggered by diverse factors. Treatments used for non-bacterial gastritis include proton pump inhibitors, histamine H2 receptor inhibitors, and antacids, and their use is linked to various side effects. Research on alternative therapeutics using food or food-based products is extensive, mostly in preclinical research. We aimed at documenting the clinical advances in food-based therapies as alternative therapeutics for gastritis. Articles with information on the treatment of gastritis with food or food-based products published until December 1, 2020 were identified through a systematic search in PubMed Medline Database. Additionally, references of retrieved articles were screened for relevant reviews and meta-analyses. Two investigators independently selected and reviewed the titles and abstracts of articles and extracted the study characteristics (PICO framework) and key findings. Dual quality assessment and data extraction were performed. We found 28 clinical studies evaluating garlic, turmeric, red peppers, broccoli sprouts, cranberry juice, honey, oils, and probiotics contained in different foods, such as juices, yogurt, and cheese. The existing literature presents a high risk of bias, and results of the same should be evaluated and replicated with precaution; more rigorous clinical studies are lacking.

Inhibitory activity of aromatic plant extracts against dairy-related Clostridium species and their use to prevent the late blowing defect of cheese.

The aim of the present work was the selection of aromatic plant essential oils (EOs) and/or ethanolic extracts (EEs) to prevent the late blowing defect (LBD) of cheese caused by Clostridium spp. EEs resulted more effective than EOs to inhibit dairy-borne Clostridium spp. in vitro. Savory, hyssop, lavender and tarragon EEs, which showed the lowest minimal inhibitory concentration against Clostridium tyrobutyricum, were selected to study the prevention of LBD caused by this bacterium in cheese. Addition of savory and lavender EEs to cheese milk delayed LBD by 2 weeks, but at the end of ripening these cheeses showed similar clostridial vegetative cells counts, spoilage symptoms and propionic, and butyric acids levels than blown control cheese. Tarragon EE, with the highest content in caffeic acid, also delayed LBD by 2 weeks, but it was more effective to inhibit Clostridium, since cheese with tarragon EE showed minor LBD symptoms, lower vegetative cells count and lower concentrations of propionic and butyric acids than the rest of cheeses made with EEs. This fact could be also attributable to the greater number of antimicrobial terpenes (1,8-cineole, 4-terpineol, α-terpineol, isoelemicin, methyl eugenol, and methyl trans-isoeugenol) detected in this cheese. This is the first report on the application of EEs to control C. tyrobutyricum in cheese.

Linoleic acid enrichment of cheese by okara flour and Geotrichum candidum overexpressing Δ12 fatty acid desaturase.

BACKGROUND: Mold-ripened cheeses have low levels of unsaturated fatty acids (UFAs). Geotrichum candidum is an adjunct culture for the development of Geotrichum-ripened cheese but has a low ability to produce high levels of UFAs. Δ12 fatty acid desaturase (FADS12) is a pivotal enzyme that converts oleic acid (OA) to linoleic acid (LA) and plays a vital role in UFA biosynthesis. By investigating FADS12 catalytic activity from various species with OA substrates, we found that FADS12 from Mucor circinelloides (McFADS12) had the highest catalytic activity for OA. RESULTS: In the current study, a plasmid harboring McFADS12 was constructed and overexpressed in G. candidum. Our results showed that LA production increased to 31.1 ± 1.4% in engineered G. candidum - three times higher than that in wild-type G. candidum. To enhance LA production, an exogenous substrate (OA) was supplemented, and the yield of LA was increased to 154 ± 6 mg L-1 in engineered G. candidum. Engineered G. candidum was used as an adjunct culture for Geotrichum-ripened cheese production. The LA level reached 74.3 ± 5.4 g kg-1 cheese, whereas the level of saturated fatty acids (SFAs) decreased by 9.9 ± 0.5%. In addition, the soybean byproduct (okara) was introduced into the engineered G. candidum growth and the level of LA increased to 126 ± 4 g kg-1 cheese and the percentage of UFAs:SFAs increased from 0.8:1 to 1.3:1. CONCLUSION: This study offers a suitable technology for converting SFAs to UFAs in Geotrichum-ripened cheeses and provides a novel trend for converting soybean waste into a value-added product. © 2022 Society of Chemical Industry.

Effect of Bear Garlic Addition on the Chemical Composition, Microbiological Quality, Antioxidant Capacity, and Degree of Proteolysis in Soft Rennet Cheeses Produced from Milk of Polish Red and Polish Holstein-Friesian Cows.

This study aimed to assess the effect of milk source and bear garlic addition on the selected properties of soft rennet cheese. Cheeses were produced from cow milk derived from two sources: Polish Red cows (PR) and Polish Holstein-Friesian cows (PHF) with a 0.5% (w/w) addition of bear garlic (Allium ursinum L.) dried leaves. Chemical composition and fatty acid profiles (GC) were determined in fresh cheeses. Fresh and stored for two weeks cheeses were subjected to microbiological studies, i.e., total aerobic bacteria count (TABC); count of Lactococcus sp., yeast and molds; coliforms; analysis of the proteolysis extension by means of o-phthaldialdehyde (OPA) assay and free amino acids content (HPLC); antioxidant capacity as 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and ferric reducing antioxidant power (FRAP); as well as pH and water activity. Cheeses with bear garlic herbs were more prone to proteolysis but this was not accompanied by any effect on the microbial counts, water activity or pH. Cheeses produced from PR milk contained less monounsaturated fatty acids (MUFA) but were richer in n-3 PUFA and had a lower n-6/n-3 FA ratio than cheeses from PHF milk. Bear garlic addition increased DPPH anti-radical power but had less of an effect on the FRAP values.