Construction of hypoallergenic microgel by soy major allergen β-conglycinin through enzymatic hydrolysis and lactic acid bacteria fermentation

Soy allergenicity is a public concern, and the combination of multiple processing methods may be a promising strategy for reducing soy allergenicity. In this study, a novel two-step enzymatic hydrolysis followed by lactic acid bacteria fermentation was proposed for the construction of hypoallergenic soybean protein microgel. β-Conglycinin was used as the main soy allergen. The effects of different enzymatic hydrolysis (Alcalase, Neutrase, and Protamex) and LAB fermentation on β-conglycinin microgel formation and its immunoreactivity were investigated. Results showed that the use of different enzymes and the attainment of different degrees of hydrolysis affected the particle distribution and zeta potential in the microgels and leads to differences in microstructure and immunoreactivity. All hydrolysates compared with intact protein accelerated the formation of gel during LAB fermentation. Among the three assayed enzymes, fermented Protamex hydrolysates at 60 min (PF-60) demonstrated a microgel with an overall reduced average particle size (741.20±7.18 nm), lower absolute values of zeta potential (10.43±0.65 mV), and regular gel network. The antigenicity and IgE-binding capacity decreased to the lowest value of 0.30 % and 6.93 %, respectively. Peptidomics and immunoinformatic analysis suggested that PF-60 disrupted 17/30, 16/44, and 23/75 epitopes in the α, α', and β subunits, respectively. Unlike the LAB-fermented unhydrolyzed β-conglycinin disrupted epitopes mostly located at the loop domain, PF-60 primarily promoted the exposure and disruption of allergen epitopes with β-sheet structure located at the core barrel domain. These findings can provide new perspectives on the preparation of hypoallergenic soybean-gel products on edible particulate systems.

Enhancement of the organic acid content and antioxidant capacity of yellow whey through fermentation with Lacticaseibacillus casei YQ336

Fermentation is considered an effective tool for improving the functional characteristics of food. In this study, Lacticaseibacillus casei YQ336 was used to ferment yellow whey, and physical and chemical analysis was performed to identify the changes in the nutritional components and antioxidant activity of the fermented yellow whey. Non-targeted metabolomics was used to study the transformation of small molecular substances in the fermented yellow whey. After 48 h of pure culture fermentation with L. casei YQ336, the pH of yellow whey decreased significantly (p < 0.05). Meanwhile, the content of total acids, organic acids, sugars, total phenols, and total flavonoids and the antioxidant activity showed a significant increase (p < 0.05). A total of 628 differential metabolites were identified between fermented and unfermented yellow whey samples, of which 293 were upregulated and 335 were downregulated. After fermentation, due to the growth and metabolic activity of L. casei YQ336, meaningful metabolites such as homovanillic acid, lactic acid, oxalic acid, L-glutamic acid, and phenylalanine, as well as phenyllactic acid, gallic acid, and genistein were produced. This increased the organic acid content and antioxidant activity of yellow whey. The findings provide a theoretical and practical basis for further research on the bio-functional activity of yellow whey and the recycling and utilization of food by-products.

Improving flavor, bioactivity, and changing metabolic profiles of goji juice by selected lactic acid bacteria fermentation

Lactic acid bacteria (LAB) have exhibited strain/species specificity for different food matrices. We investigated the impact of LAB fermentation on the flavor, chemical profile, and bioactivity of goji juice. The colony counts of five selected strains reached above 8.5 log CFU/mL. The fermentation increased the organic acids, decreased the sugars, and improved the sensory quality of goji juice. The majority of the strains had increased acetic acid, heptanoic acid, ethyl phenylacetate, and linalool levels. Specific strains suppressed α-glucosidase and pancreatic lipase activities and increased the antioxidant activities of fermented goji juice. Based on non-targeted metabolomics and activities, 23 important differential metabolites were screened among 453 metabolites. The quantification results showed that isoquercitrin and m-coumaric content varied among strains, reflecting the strain specificity in flavone and flavonol biosynthesis and phenylalanine, tyrosine, and tryptophan biosynthesis. These findings will provide useful information for fermented goji juice biochemistry research.

Improvement of antioxidant properties of jujube puree by biotransformation of polyphenols via Streptococcus thermophilus fermentation

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Streptococcus thermophilus enriched polyphenols in fermented jujube puree.

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Fermentation improved jujube puree DPPH scavenging capability by 26%.

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12 phenolics were identified as differential metabolites.

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Fermentation could be a promising approach to improve jujube phenolic quality.

To investigate the effect of lactic acid bacteria fermentation on jujube bioactivity, Streptococcus thermophilus was used to ferment jujube puree. The number of viable bacteria cells, physicochemical properties, phenolics profile and antioxidant capacity were analyzed, and their correlation were investigated. Streptococcus thermophilus exhibited a high growth capacity in jujube puree, and significantly (p < 0.05) increased the total phenolics content, 2,2-Diphenyl-1-picrylhydrazyl (DPPH) scavenging activity and reducing power after 48 h fermentation, while 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) scavenging activity was decreased. 12 differentially metabolized polyphenols were identified in fermented jujube puree. Upregulated phenolics exhibited a positive correlation with DPPH radical-scavenging ability and reducing power. This work demonstrated that Streptococcus thermophilus fermentation can be an effective method with great practical application potential to improve the antioxidant activity in jujube puree by modifying the phenolic compositional quantity and quality.

Suitability of pitaya fruit fermented by sourdough LAB strains for bread making: its impact on dough physicochemical, rheo-fermentation properties and antioxidant, antifungal and quality performance of bread

The objective of this study was to investigate the suitability of incorporating pitaya fruit fermented by antifungal LAB strains Lactiplantibacillus plantarum and Pediococcus pentosaceus at 1: 30 °C for 24h or 2: 31 °C for 19.5h as an ingredient with respect to bread making performance and bio-preservation effect. Underlying mechanisms related to gluten protein hydrolysis, starch hydrolysis, and yeast activity in dough were explored. The antioxidant activity, antifungal activity and bread making performance of the resulted breads were analyzed. Also, the antifungal phenolic acids in the breads were identified and quantified. Incorporation of fermented substrates in dough increased yeast activity and gas production capacity, but decreased gas retention capacity. This was attributed to increased dough acidity after incorporating fruit substrates. As a result, reducing sugar and free sulfhydryl (SH) groups increased in these doughs which indicated higher starch and gluten protein hydrolysis, respectively. However, SH groups increased at lower rate in presence of substrates fermented by L. plantarum and P. pentosaceus at condition 2 than 1. This could be due to improvement of gluten network as revealed by decreased α-helix (%) and increased β-turn (%) in secondary gluten structures in these doughs which subsequently resulted in more homogeneous microstructural properties than in presence of unfermented substrate compared to wheat dough. Subsequently, bread specific volume increased (6.6–20.0%) in presence of fermented substrates, especially fermented by L. plantarum at (2). Moreover, bread incorporated with fermented substrates (P. pentosaceus than L. plantarum at 1 than 2) had enhanced antioxidant activities, lower fungal growth rates based on challenge tests and mold free shelf life. Antifungal phenolic acids such as gallic acids, caffeic acid, protocatechuic acid were only detected in bread incorporated with fruit substrates, and their total content higher in fermented substrates.

The role of rye bran acidification and in situ dextran formation on structure and texture of high fibre extrudates

High insoluble dietary fibre content causes challenges with structure and texture in extrusion. This paper focused on studying the structure of extrudate enriched with rye bran modified in different ways. Fermentation of rye bran with dextran-producing Weissella confusa (with 10 g/100 g, 5 g/100 g and 0 g/100 g added sucrose as substrate for dextran production), in situ enzymatic production of dextran in the bran and chemical acidification of bran with lactic acid were compared in extrusion trials. Endosperm rye flour was the base in extrusion, of which 32 g/100 g was substituted for rye bran. Fermentation with dextran production showed similar improvement in extrudate expansion as chemically acidified bran samples (489 and 493%), in comparison with native bran (420%). Similarly, these treatments decreased extrudate hardness and increased crispiness index (CI) (16 N, 0.06 and 14 N, 0.071 respectively) compared to the control (39 N, 0.008). Enzymatically produced dextran did not affect expansion, although it decreased hardness (26 N) and increased CI compared to the control (0.023). Chemical changes in the fermented and acidified rye bran included reduction in insoluble dietary fibre (DF) (19 g/100 g → 17 g/100 g) and increase in soluble DF (5.17 g/100 g → 5.51-7.19 g/100 g), as well as soluble protein (8 g/100 g → 11 g/100 g) content. Lactic acid bacteria fermentation or acidification is therefore a promising method to increase the functionality of rye bran in extrusion.

Safety and quality parameters of ready-to-cook minced pork meat products supplemented with Helianthus tuberosus L. tubers fermented by BLIS producing lactic acid bacteria

The aim of this study was to evaluate the influence of additives of Jerusalem artichoke (JA), fermented with P. acidilactici KTU05-7, P. pentosaceus KTU05-9, L. sakei KTU05-6, on the quality and safety parameters of ready - to cook - minced pork (RCMP). Fermented JA additives reduced pH of the meat products and decreased water holding capacity (WHC) from 2.01 till 2.93 %. Concentrations of biogenic amines in RCMP with additives of the lactic acid bacteria (LAB) - fermented JA were significantly lower comparing with control sample. The number of pathogenic bacteria in artificially contaminated meat samples was significantly reduced in case of LAB-fermented JA additives. The highest antimicrobial activity was obtained using P. acidilactici fermented JA additives. The amounts of microbial pathogens E. coli and Ent. faecalis, S. aureus and Streptococcus spp. were determined 3.41, 3.38, 3,96 and 4.74 log CFU/g correspondingly, whereas without LAB-fermented JA additives were 8.94, 7.75, 8.82 and 8.58 log CFU/g, correspondingly. A possibility to improve sensory properties (flavor) of RCMP using LAB fermented JA additives was investigated. The composition of volatile compounds of RCMP without additive and with LAB-fermented JA additives was analyzed using gas chromatography-mass spectrometry (GC-MS). The results of sensory evaluation of meat products supplemented with fermented JA additives revealed specific odor, which is pleasant and acceptable for consumers might be explainable that LAB-fermented JA additives have shown considerable differences mainly due to the accumulation of volatiles such as toluene, ethylbenzene, decane, undecane, 2 methyl undecane. N-morpholinomethyl-isopropyl-sulfide, 6-undecilamine and N,N-dimethyl-1-pentadecanamine were not determined in RCMP with LAB-fermented JA additives. The results obtained show, that P. acidilactici fermented JA 5 % additive is most suitable for the RCMP processing in order to prevent microbiological spoilage, increase volatile compounds and acceptability of the products.