Pulsed electric field for shalgam juice: effects on fermentation, shelf-life, and sensory quality.

BACKGROUND: Pulsed electric field (PEF) has become a reality in the food industry as a non-thermal application. PEF is used due to its benefits such as increasing the extraction of anthocyanin or other bioactive substances, shortening the fermentation time, and reducing the microbiological load by electroporation. This study aimed to determine the effect of PEF pretreatment on the fermentation, chemical, microbiological, and sensory properties of shalgam juice. For this purpose, PEF with 1 kV cm-1 of field strength was used as a pretreatment for shalgam juice and changes in control and PEF-treated samples were monitored during fermentation and 70 days of cold storage (4 °C). RESULTS: The pH and lactic acid content during fermentation were similar for both samples. The effect of PEF on pH (3.15-3.39), titratable acidity (4.35-5.49 g L-1 ), total phenolic content (279-766 mg mL-1 GAE) and antioxidant activity (694-2091 µmol Trolox mL-1 ) during storage was insignificant. PEF-treated samples had lower total aerobic mesophilic bacteria (~9%) and lactic acid bacteria (~3%) counts than the control samples at the end of 70 days. Sensory analyses performed at 30th and 60th days of storage with 74 panelists revealed that the color, taste, sourness, saltiness, bitterness, and general acceptability were not inversely affected by PEF. CONCLUSION: Our results could be a basis to produce shalgam juice commercially by PEF treatment. Although more studies with new experimental designs should be carried out, preliminary results indicated that the use of PEF might have a potential for fermented products such as shalgam juices. © 2023 Society of Chemical Industry.

Elucidation of the initial bacterial community of Ezine PDO cheese using next-generation sequencing.

This study aims to reveal initial bacterial consortia of Ezine PDO cheeses comprehensively by following a metagenomic approach. A total of 8 artisanal Ezine cheese samples were collected from the Bayramiç and Ezine districts of Çanakkale province of Turkey. Ezine cheese was found to contain Firmicutes, Bacteroidetes, and Proteobacteria phyla dominantly. Streptococcus, Lactococcus, and Lactobacillus genera dominated the microbiota with relative abundances of 4.47-56.07%, 7.33-20.34%, and 1.21-25.12%, respectively, followed by Bacteroides and Prevotella genera. Excluding two cheese samples obtained from the Ezine district, the most dominant species was Streptococcus thermophilus (8.24-54.34%). It was also found in greater proportions in the cheeses of the Bayramiç district. Unexpectedly, Lactobacillus graminis (11.50-23.63%) was the most abundant species in two samples collected from the Ezine district. However, lower bacterial diversity was determined in the samples collected from the Bayramiç district. The lowest species richness was 129 OTU-species in the cheeses from the Bayramiç district while the highest species richness was 267 OTU-species in cheeses from the Ezine district. In addition, the Simpson index was the highest in cheeses from the Ezine district, where different species were evenly distributed. Permutational multivariate analysis of variance tests also confirmed that the differences in the structure of bacterial consortia in cheeses from two different districts were statistically significant. This study will provide pioneer data for further investigations on the role of complex bacterial composition in maintaining and improving the quality and safety of Ezine cheese.

Screening Lactobacillus strains from artisanal Turkish goatskin casing Tulum cheeses produced by nomads via molecular and in vitro probiotic characteristics.

BACKGROUND: Eleven Lactobacillus (L.) strains were newly isolated from traditional Turkish Tulum cheeses and were characterized regarding their potential probiotic characteristics (bile and acid tolerance, gastric and pancreatic juice tolerance, lysozyme tolerance, adhesion ability), virulence determinants (hemolytic activity, antibiotic resistance, biogenic amine production), and functional properties (antibacterial activity, ß-galactosidase activity, production of exopolysaccharides, cholesterol removal). RESULTS: These isolates were identified as L. brevis, L. plantarum, L. paracasei, L. coryniformis, L. rhamnosus and L. helveticus by 16S rRNA sequencing. With regard to safety aspects, none of the tested Lactobacillus isolates showed hemolytic activity or biogenic amine production. All the Lactobacillus isolates except isolate 24 were found to be sensitive or intermediate sensitive to penicillin, which is a frequently used antibiotic. Nine Lactobacillus isolates showed antibacterial activity against Staphylococcus aureus ATCC 25923, while only isolates 15 and 449 exhibited inhibitory activity against Listeria monocytogenes ATCC 7644. All isolated strains survived, even in the presence of 10.00 g L-1 bile after 48 h, and exhibited good survival at pH 3, but only two isolates survived at pH 2. Among the strains, isolate 15 exhibited satisfactory auto-aggregative, cell-surface hydrophobicity features, cholesterol-lowering activity and good acid tolerance. Isolate 15 also showed the strongest bile and simulated pancreatic juice resistance and moderate lysozyme tolerance. CONCLUSION: These outcomes suggest that isolate 15, identified as a L. plantarum strain from Tulum cheese, may be a promising probiotic candidate and could be suitable for use in several fermented foods. © 2020 Society of Chemical Industry.

A study on rheological properties, sensory evaluation and shelf life of ayran-shalgam mixtures.

Ayran, a dairy-based fermented beverage, and shalgam, a plant-based fermented beverage were mixed [25% ayran + 75% shalgam (v/v), 50% ayran + 50% shalgam (v/v) and 75% ayran + 25% shalgam (v/v)] and rheological data were obtained at different temperature levels (4-12 °C). Power law model was used to describe the data. Temperature had no effect on the flow behavior index, but it affected the consistency index of the mixtures. Ayran-shalgam mixtures had similar flow behavior index with that of shalgam irrespective of the levels of ayran or shalgam. However, consistency index increased as the amount of ayran increased in the mixtures at a constant temperature. Mixture with the higher amount of ayran [75% ayran + 25% shalgam] had the highest scores in sensory evaluation. Shelf life analyses up to 4 weeks at 4 °C indicated that serum separation increased till the second week and then stabilized for all mixtures. Slight increase (0.05-0.1 unit) in pH was observed during the first week then pH values were stabilized just like the serum separation. Microbiological analyses revealed that mixtures had a similar shelf life with that of ayran. Consequently, mixture of two different fermented beverages could be possible with similar flow behavior and shelf-life, and ayran-shalgam mixture has a huge potential for commercial production. This study may be a basis for designing new products to fulfill the healthy diet demands.

Perspectives on the yogurt rheology.

The oral processing of yogurt is a dynamic process involving a series of deformation processes. Rheological knowledge is essential to understand the structure and flow properties of yogurt in the mouth and to explore its relationship with sensory perception. Yogurt is rheologically characterized as a non-Newtonian viscoelastic material. The rheological properties of yogurt are affected by many factors, from production to consumption. Therefore, rheological measurements are widely used to predict and control the final quality and structure of yogurts. Recent studies focus on the elucidation of the effects of cultures and processes used in production, as well as the design of different formulations to improve the rheological properties of yogurts. Moreover, the science of tribology, which dominates the surface properties of interacting substances in relative motion to evaluate the structural sensation in the later stages of eating in addition to the rheological properties that give the feeling of structure in the early stages of eating, has also become the focus of recent studies. For a detailed comprehension of the rheological properties of yogurt, this review deals with the factors affecting the rheology of yogurt, analytical methods used to determine rheological properties, microstructural and rheological characterization of yogurt, and tribological evaluations.

Biological activities, Peptidomics and in silico analysis of low-fat Cheddar cheese after in vitro digestion: Impact of blending camel and bovine Milk.

Cheesemaking with camel milk (CM) presents unique challenges and additional health benefits. This study involved preparing low-fat Cheddar cheese (LFCC) by blending bovine milk (BM) with varying levels of CM. Control cheese was made exclusively with BM. After 180 days of ripening, LFCC samples underwent in vitro digestion to determine antioxidant capacities, α-amylase and α-glucosidase inhibition, and angiotensin-converting enzyme inhibition. The peptide profile of LFCC treatments was analyzed using liquid chromatography-quadrupole-time of flight-mass spectrometry. Antioxidant and biological activities were influenced by BM-CM blends and digestion. At days 120 and 180, the number of αs1-casein-derived peptides increased in all samples except for LFCC made with 15% CM. Generally, 88 peptides exhibited ACE inhibition activity after 120 days of ripening, increasing to 114 by day 180. These findings suggest that ripening time positively affects the health-promoting aspects of functional cheese products.

Characterization of bioactive peptides derived from goatskin Tulum cheese of the Eregli region at different stages of ripening.

The study aimed to identify peptide profiles and observe peptide dynamics of goat skin Tulum cheese throughout 180 days of ripening. A total of 222 peptides were obtained derived from ß-,αs1-, and αs2-casein by LC-MS/MS. According to the SDS-PAGE analysis results, the amount of αs- and ß-CNs decreased depending on the increase in ripening time. Therewith, the number of bioactive peptides increased during ripening. It was observed that especially aminopeptidase and carboxypeptidase activities were effective in the formation of peptides during the ripening of Tulum cheese. Peptides released by proteolysis of caseins showed 15 different bioactivities including antibacterial, antifungal, anticarcinogenic, immunomodulator, anti-obesity, GLP-1 secretion enhancer, cathepsin B inhibitor, ACE inhibitor, antidiabetic, cholesterol regulator, anti-amnesic, antioxidant, brain function enhancer, anti-inflammatory, and skin regenerative properties. It was observed that the number of bioactive peptides increased during ripening so especially ripening for a long time of Tulum cheeses can have positive effects on human health and create significant opportunities as a functional food.