查看更多>>摘要：Cross-over fermentations are processes in which a microorganism from one traditional fermentation process is introduced onto a new substrate and/or to a new partner. Here we show that Aspergillus oryzae normally used for the production of miso, a fermented soybean paste from Asia, can be applied to a traditional European fermented dairy product quark cheese, produced by fermenting milk with Lactococcus lactis. This cross-over fermentation resulted in a product with intense aroma properties, mainly due to high amounts of volatile fatty acids, ethyl esters, higher alcohols and ketones. Active metabolism of A. oryzae was required for alcohol production, whereas fat degradation occurred mainly due to enzymatic activities. Traditionally used practices in miso production, like mixing, addition of various amounts of salt and variations in fat content of the substrate altered metabolic and enzymatic properties of A. oryzae resulting in differences in final product characteristics. Aroma intensity of the product was shown by comparing volatile organic compounds with blue and white mould cheese. This study showed the potential of cross-over fermentation for novel food products. The enormous diversity of microorganisms used in traditional fermentation processes and the vast number of alternative substrates offer numerous opportunities for further novel fermented product development.
查看更多>>摘要：Dough elasticity and bread quality depend on the gluten network formation which by nature is the oxidative crosslinking of glutenin. It is known for long, either in the kitchen or in the laboratory, sodium chloride (NaCl) enhances dough rheological properties while itself is not an oxidant. However, besides NaCl induced gluten aggregation, the molecular mechanism behind this phenomenon is largely unknown. Azodicarbonamide (ADA) and Vitamin C (Vc) improve dough qualities with different mechanisms. Here, response surface methodology (RSM) was used to study the synergistic effect of ADA, Vc and NaCl on the dough and subsequent bread qualities. Results show that NaCl dominates the dough alveographic characters in the presence of oxidative flour improvers, and fine tune of NaCl concentration profoundly impacts subsequent bread properties. Consistent with free sulfhydryl assay and glutenin gel electrophoresis analysis, simulation study reveals that NaCl concentration affects glutenin conformation and intermolecular interaction which in turn impacts their orientation adjustment that lead to sulfhydryl contact and crosslinking.
Zhang, XiaoyunGu, NingZhou, YouGodana, Esa Abiso...
9页
查看更多>>摘要：Our previous study showed that the biocontrol efficacy of Rhodotorula mucilaginosa against postharvest diseases of strawberries can be significantly enhanced by chitosan. Proteome analysis of R. mucilaginosa induced by chitosan has preliminarily explored the molecular mechanisms involved in the enhanced antagonistic efficacy of R. mucilaginosa induced by chitosan. In this study, transcriptome analysis of R. mucilaginosa cultured with and without chitosan was performed, and the activities of CAT, PPO, POD, and SOD were also investigated to further explore the involved mechanisms. The results indicated that the activities of these antioxidant enzymes in R. mucilaginosa were all significantly increased by 0.5 g/100 mL chitosan. Especially, POD activity was about 1.5 - fold higher than the control. Transcriptome and bioinformatic analysis revealed that significant number of genes involved in growth and reproduction, adhesion, energy production, oxidative stress response and other stress response were all induced by chitosan, which resulted in the enhanced antagonistic efficacy of R. mucilaginosa. These results provide a reference for the future study on controlling postharvest disease of fruit and vegetables by antagonist yeast and provide a theoretical basis for the practical application of antagonist yeast.
查看更多>>摘要：The foodborne pathogen Listeria monocytogenes is the major cause of listeriosis. We isolated a novel lantibiotic subtilin JS-4 from Bacillus subtilis JS-4 and analyzed its effects against L. monocytogenes. The bacteriocin was extracted with n-butanol, purified by Sephadex LH-20 gel-filtration chromatography and semi-preparative RP-HPLC, and characterized by MALDI-TOF-MS and MALDI-TOF-MS/MS. The molecular mass of subtilin JS-4 was 3346.6 Da, and its amino acid sequence was similar to that of subtilin except for the Ala 15 -> Val and Leu 24 -> Ile substitutions. Subtilin JS-4 showed good thermal and pH stability but was inactivated by proteases. It also showed a broad antimicrobial spectrum against Gram-positive bacteria. The antibacterial mechanism of subtilin JS-4 against L. monocytogenes was investigated using confocal laser-scanning microscopy, scanning and transmission electron microscopy, which revealed that subtilin JS-4 increased cell membrane permeability, triggered K+ leakage and pore formation, damaged cell membrane integrity, altered cell morphology and intracellular organization. Taken together, subtilin JS-4 is highly effective against foodborne pathogens, and should be considered as an antibacterial preservative in the food industry.
查看更多>>摘要：Frequently, Bifidobacterium breve strains are found to be CLA-producers. Previous studies revealed that free linoleic acid inhibited the growth of bifidobacterial strains, however, the reason why bifidobacteria with different CLA-producing abilities exhibit similar adaptive modes to linoleic acid (LA) stress is still unknown. We used B. breve strains CCFM683 and CCFM1025, which exhibit 85% and 0% CLA conversion rates, respectively, together with metabonomics analyses, to elucidate the putative factors involved in the protection against LA stress. We found that the pathways involved in amino acid, carbohydrate, and fatty acid metabolisms were much more active in B. breve CCFM1025. Moreover, L-cysteine, L-methionine, mannitol, and 18-hydroxy-oleate accumulated to a much higher level in B. breve CCFM1025, probably providing primary protection. In particular, the levels of several antioxidant compounds, including L-ascorbate, glutathione, ubiquinol-6, 3-demethylubiquinol-7, and demethylmenaquinol-7, were much higher in B. breve CCFM1025, suggesting that these antioxidants may provide a primary protective effect to the strain without CLA-producing abilities.
查看更多>>摘要：Primer-probe sets to detect Bacillus cereus and/or B. subtilis in food products were developed based on panX (a pan-genome analysis tool). Data for 60 B. cereus strains and 131 B. subtilis strains retrieved from the NCBI RefSeq database were analyzed by panX. Primer-probe sets for B. cereus (ccpA) and B. subtilis (cotQ) were developed by comparing the core genomes of the two bacteria. The developed primer-probe sets' sensitivity and selectivity were identified using 45 strains, including ten B. cereus, five B. subtilis, 13 non-B. cereus and non-B. subtilis strains, and 17 non-Bacillus strains using real-time polymerase chain reaction (PCR). The developed primer-probe sets displayed high sensitivity and selectivity for B. cereus and B. subtilis, validated with two different real-time PCR instruments. PCR analysis using the developed primer-probe showed high efficiency in buffer and milk samples. These results indicate that the primer-probe sets developed based on the panX analysis can be used effectively for detecting B. cereus and/or B. subtilis in food products.
查看更多>>摘要：The purpose of this study was to evaluate the physicochemical stability and potential gastrointestinal fate of the lutein-enriched high internal phase emulsions (LE-HIPE) stabilized by egg yolk-modified starch complex. Results showed that the physical stability and lutein retention of the LF-HIPE stabilized by egg yolk-hydroxypropyl distarch phosphate (EY-HPDSP) or egg yolk-octenyl succinic anhydride starch (EY-OSA) complex were both significantly improved at 4 degrees C. However, the LE-HIPE stabilized by EY-HPDSP complex showed better physical stability, lower lipid oxidation and higher lutein retention during storage at 37 degrees C than that stabilized by EY-OSA complex, which was related with the results of smaller droplets, more restricted water and oil protons for the former. In vitro digestion results showed that high level of HPDSP in LE-HIPE was beneficial to the improvement of the bioaccessibility of lutein. These results could be useful in the development of nutrient delivery system based on egg yolk-modified starch complex stabilized HIPE.
Yildirim-Yalcin, MeralSadikoglu, HasanSeker, Mahmut
10页
查看更多>>摘要：Grape juice, maize starch cross-linked with sodium trimetaphosphate and glycerol were used to prepare edible film. The effects of grape juice:water volume ratio (10:90-50:50), cross-linked maize starch (3-5%, w/v), and glycerol (0.5-1.0%, w/v) concentration on the solubility, color, phenolic content, and barrier properties of edible films was examined with response surface methodology. Optimized film with low solubility (0.53 g soluble solid g 1 total solid), yellowness index (8.71), oxygen and water permeability coefficients (8.48 cm(3)mu m m(-2)d(-1)kPa(-1); 1.33 gmm m(-2)h(-1)kPa(-1), respectively), and high phenolic content (43.34 mg GAE 100 g(-1) dm) was found to be 16.15:83.85 of grape juice:water ratio, 3.61% of starch and 0.5% of glycerol. The best formula that meets defined quality constraints for edible film was used for the preservation of physicochemical and microbiological properties of chicken breast fillets. The amount of thiobarbituric acid-reactive substance in the coated chicken fillets decreased from 1.98 to 0.91 mg MDA kg(-1) as a result of reduction of oxygen permeability and availability. Total aerobic mesophilic, psychrophilic, and Enterobacteriaceae counts decreased by 1.58, 0.94, and 0.85 log, respectively. These results clearly proved that coating chicken fillets with grape juice-based edible film affected positively lipid oxidation and microbial growth during cold storage.
查看更多>>摘要：Natural antioxidants are important for the stability and nutritional properties of oils. Therefore, this study explored the stability of rice bran oil with different ratios of oryzanol to tocopherols during heating at 110 degrees C and 170 degrees C. In addition, the relationship between the loss of oryzanol and tocopherols and physicochemical indexes was investigated through multiple linear regression and Pearson correlation analyses. The results showed that the optimal ratio of oryzanol to tocopherols was 8:1, the oxidation stability index of rice bran oil reached 10.26 h and the formation of free fatty acids and secondary oxidation products was markedly inhibited. Additionally, the degradation of tocopherols in rice bran oil followed the first-order kinetic model. Moreover, both oryzanol and tocopherols were responsible for the antioxidant properties of rice bran oil although oryzanol had a bigger contribution. Therefore, these results may provide interesting insights into the appropriate ratio of these minor compounds in oil products. Furthermore, the establishment of a multiple linear regression model may also be valuable in exploring the antioxidant behavior of oryzanol and tocopherols during heating.
查看更多>>摘要：The inhibitory effects of soybean peptides (SPTs) with four different molecular weights (MWs) (SPT1, SPT2, SPT3, and SPT4) on porcine pancreatic alpha-amylase (PPA) were evaluated by spectrofluorimetry and enzyme inhibition analysis. SPT1, SPT2, and SPT3 were mixed inhibitors with competitive and uncompetitive inhibitory effects on alpha-amylase. SPT with lower MWs inhibited PPA more strongly than those with higher MWs. SPT binding interactions with PPA were mainly non-covalent, i.e., van der Waals interactions and hydrogen-bonding. SPT interacted with Tyr, Trp and Phe residues in PPA and quenched its intrinsic fluorescence, via a static quenching mechanism. SPT of higher MW had stronger binding interactions and more stable complexes with PPA than those of lower MW. SPT1, SPT2 and SPT3 have potential inhibitory effects on PPA activity in vivo, which could delay the digestion of starchy foods. These findings have laid a theoretical foundation for slowing starch digestibility by formulation with peptides and thereby developing novel low-glycaemic index functional foods.
NSTL
Elsevier