Wrenhanley0255

During tempeh production, boiling was considered as heat treatment that could significantly reduce or eliminate bacterial population in soybean before fungal inoculation. The objective of this study was to enumerate and trace Enterobacteriaceae communities in pre-boiling soybean, post-boiling soybean, and fresh tempeh designated as RTI and EMP. Standard plate count and qRT-PCR were employed to determine the culturable and non-culturable bacteria, while Enterobacterial Repetitive Intragenic Consensus PCR was conducted to determine the intraspecies genomic variations. Fresh tempeh from both RTI and EMP contained approximately 107 and 108 CFU/g of Enterobacteriaceae respectively. The number of bacteria in pre-boiling soybean were 10,000 times lower than in fresh tempeh. Our study showed that most Enterobacteriaceae were severely injured or quiescent during boiling process and quickly recovered up to 109 CFU/g in fresh tempeh. Some Klebsiella isolates found in tempeh were genetically identical to isolates in soybean, but different from those of medical isolates. This study suggested that soybean could be the main origin of Klebsiella in fresh tempeh.Bacillus amyloliquefaciens S0904 was selected as a hyperproducer of a glutamine-hydrolyzing enzyme which was identified as a γ-glutamyltranspeptidase catalyzing both hydrolysis and transpeptidation of glutamyl substrates. The signal peptide-truncated recombinant enzyme (rBAGGT) showed two-fold enhanced specific activity for hydrolysis and optimum pH shift to pH 7 from pH 6 compared with the wild type. The hydrolysis activity of rBAGGT was tolerant against NaCl up to 2.5 M, whereas the transpeptidation activity decreased by NaCl. At pH 6, the addition of 1.5 M NaCl not only enhanced the hydrolysis activity but also inhibited the transpeptidation activity to be ignorable. By contrast, at pH 9 in the absence of NaCl, the alkaline pH-favored transpeptidation activity was 99% of the maximum with only 15% of the maximum hydrolysis activity. In conclusion, the hydrolysis and transpeptidation activities of the recombinant BAGGT is controllable by changing pH and whether or not to add NaCl.

The online version contains supplementary material available at 10.1007/s10068-021-00928-6.

The online version contains supplementary material available at 10.1007/s10068-021-00928-6.Three bacteriophages (phage), ΦWC53, ΦWC54, and ΦWC56, of Weissella were isolated from watery kimchi and characterized. ΦWC53 belonged to Siphoviridae and ΦWC54 and ΦWC56 belonged to Myoviridae family. By one-step growth, the burst sizes were 5-260 particles/infected cells and the latent periods were 20-45 min. The phages infected Weissella spp., Leuconostoc mesenteroides, and Lactobacillus spp., differently by showing clear or turbid plaques. The phage adsorption rates on lactic acid bacteria were high on Weissella and low on Leuconostoc and Lactobacillus. However, the adsorption of ΦWC53 occurred variously among Weissella spp. and Weissella host grew well in the liquid culture without lysis after challenging by ΦWC53. Tolerances of these phages to temperature showed more various than those to pH. ΦWC53 was stable at 7 °C and 30 °C, but ΦWC54 and ΦWC56 were stable only at 7 °C. Therefore, three Weissella phages belonged to the different families and indicated diverse infection patterns on Weissella, Leuconostoc, and Lactobacillus with various stabilities for pH and temperature.This study characterized the blends of corn starch with potato amylopectin (PAP) and PAP hydrolysates treated with branching enzyme (BR), pullulanase (PL), and BR-BL cocktail. PAP/PAP hydrolysates were deposited or bound (particularly in intact and PL-treated PAPs) on the surfaces of corn starch granules. Although PAP/PAP hydrolysates rarely affect the X-ray diffraction patterns of the blends, their relative crystallinities decreased. Relative to native starches, the swelling power was higher for all blends. Solubility was higher for normal starch-based blends but lower for waxy starch-based blends. All blends exhibited higher gelatinization temperatures and lower gelatinization enthalpies. Although the pasting viscosities of blends with intact PAP were higher than those of native starches, the opposite trends were found in blends with BR-, PL-, and BR-PL cocktail-treated PAPs. Overall, the PAP structures diversified the characteristics of the corn starch-PAP blends. BR- and BR-PL cocktail-treated PAPs could function as stabilizers for stable paste consistency.

The online version contains supplementary material available at 10.1007/s10068-021-00919-7.

The online version contains supplementary material available at 10.1007/s10068-021-00919-7.To investigate the effects of electrolyzed water treatment on the qualities of rice noodles prepared with semidry- milled rice flour, pasting properties and thermal properties of rice flour, and the cooking and textural properties of rice noodles were determined. Higher peak viscosity and lower melting enthalpy were observed in electrolyzed water (EW) treated rice flour. The hardness, gumminess and chewiness of rice noodle in slightly acidic electrolyzed water treated rice noodles with available chlorine concentration (ACC) 20.32 mg/L were increased significantly (p  less then  0.05). The cooking loss decreased significantly in strong acidic electrolyzed water treated noodles with ACC 10.09 mg/L treatment (p  less then  0.05). The results indicated that EW could promote the gelatinization of rice flour, and improve the textural qualities of rice noodles. Therefore EW was appropriate to be used in rice noodle production.This study examined human flavor perception and discrimination of powdered milk samples with various fat contents using two different sensory discrimination methods, DR A-Not A and 3-AFC. DR A-Not A was expected to be more effective. Using skim milk and whole milk powder, five different samples with various fat contents were prepared. Saracatinib An independent samples design was used to compare DR A-Not A and 3-AFC. Each subject performed 24 repeated tests consisting of comparisons of four different test samples from the reference sample. Signal detection d' results showed that sample discrimination was possible using DR A-Not A, but not 3-AFC. Moreover, the just noticeable difference (JND) was calculated using the results of DR A-Not A. The calculated JND was 0.47% (w/v), and the Weber fraction was 0.82. These results confirm that the DR A-Not A method is more effective for studying the human sensitivity to the fat content in food.