Multiple bacteriocin-producing Lactiplantibacillus plantarum PUK6 was isolated from misozuke-tofu, tofu pickled in miso, a traditional fermented food that has a production history of more than 800 years in the Kuma district of Kumamoto Prefecture, Japan. The PUK6 strain could grow at below 7.5% NaCl and produced both D- and L-lactic acids. In addition, it exhibited potential probiotic properties, including resistance to gastric acid and a cholesterol-lowering effect. Bacteriocins produced by the PUK6 strain were purified from the culture supernatant by ammonium sulfate precipitation, dialysis, Sep-Pak Plus tC18, and reversed-phase high performance liquid chromatography (RP-HPLC). Three peaks with high antimicrobial activity were obtained by RP-HPLC. Based on amino acid sequencing and genetic analysis by PCR, they were considered to be plantaricins A, EF, and NC8, or similar substances.
A three-dimensional (3D) food printer is an attractive tool for making highly customized foods. The quality of powders and pastes used as ink in printers has a significant impact on print performance. The present study investigated the effect of the powder preparation method on particle size and flowability of the powder. The particle size of potato powders milled by jet mills was smaller than that milled by hammer mills, and the mean diameter depended on blanching conditions prior to drying and milling. The flowability of powders decreased with decreasing particle size, and improvement in flowability was required for the fine powders manufactured by jet mill. The printability of the potato pastes was influenced by blanching conditions and particle size. In addition, manufacturing procedures for powders play an important role in determining the optimum water content of pastes for 3D printed foods.
Sake yeasts synthesize alcohols and other components, such as ethyl caproate, ethyl caprylate, and isoamyl acetate, which impart a unique and refined flavor profile to sake. In this study, a sake yeast mutant, K901C8, with high ethyl caprylate productivity was isolated from Kyokai no. 901 (K901), which has been passaged since 1993 at Yoshinogawa brewery, and its fermentative properties were investigated. This mutant was isolated from 960 antibiotic-resistant mutants obtained from 2.1× 107 cells with cerulenin as an inhibitor of fatty acid synthesis. In small-scale sake brewing experiments, the K901C8 mutant produced a high level of ethyl caprylate, which imparts a pineapple- and apricot-like flavor to sake. In the industrial-scale brewing, K901C8 showed fermentative properties similar to those of the wild-type K901, whereas K901C8 produced more ethyl caprylate than K901. These results demonstrate the potential of using K901C8 for producing high-quality sake with a novel flavor.
This study investigated the effects of rice bran protein hydrolysate (RBPH) coupled with oxidized tea polyphenols (OTP) on the physical and oxidative stability of oil-in-water emulsions. Emulsions stabilized with RBPH alone were less stable than those stabilized with both RBPH and OTP. The OTP not only improved the emulsification stability, flocculation stability, coagulation stability, and ζ-potential of the emulsions, OTP also decreased the particle size, increased the adsorption capacity of the oil–water interface for RBPH, and effectively reduced the generation of peroxide and malondialdehyde in the emulsion during storage. The stability of the emulsion during the early stage of storage was maximized when the OTP content was 1.5%; at greater contents, the OTP competed with RBPH for adsorption at the interface, which affected the distribution of RBPH on the interface and decreased the emulsion stability. The results indicate that OTP can enhance emulsion stability, providing a reference for the application of oxidized polyphenols in food emulsions.
Fish sauce is a liquid condiment prepared by fermenting fish at room temperature and high salt concentration (> 20%) for more than six months. We examined whether the application of pressurized CO2 (pCO2), mild heating, and acid protease (1%) would produce reduced-salt fish sauce in a short fermentation period. Optimal fermentation temperature and NaCl concentration were determined to be 45°C and 7%, respectively, at a fixed fermentation period (one week). Treatment with pCO2 (1 MPa), mild heating (45 °C), and acid protease (ORYENTASE AY) decreased biogenic amine content, increased free amino acid content, and enriched umami flavor. This treatment did not induce bacterial growth, and the changes in organic acid content and smell were minimal. In the presence of protease, browning was suppressed under pCO2 compared to atmospheric pressure. Thus, the application of pCO2 and protease with mild heating enabled reduced-salt fish sauce production in a short fermentation period.
This study aimed to find an effective protocol as a cooking pre-treatment for the petioles and young spikes of Petasites japonicus to reduce their contents of pyrrolizidine alkaloids (PAs), a type of natural toxin in plants such as the Asteraceae and Boraginaceae families. After determining the most common cooking pre-treatment methods for petioles and young spikes of Petasites japonicus from a survey of recipes, various treatments were examined for their effectiveness at reducing PAs. It was concluded that both boiling and soaking processes were important for the reduction of PAs in pre-treatment of cooking the petioles and the young spikes of Petasites japonicus, and that a longer soaking time had a greater effect in reducing PAs. PAs in the petioles and young spikes decreased to less than 50% of the original amount in 1 h and 6 h, respectively during soaking after boiling (and peeling).
The effect of Origanum syriacum L. essential oil (OE) on lipid oxidation, total volatiles, and sensory evaluation of cooked chicken meat was investigated. The treatments applied were 1) Control; 2) 200 ppm oregano essential oil (OEL1); 3) 250 ppm (OEL2); 4) 150 ppm sodium nitrite (E-250); and 5) 14 ppm butylated hydroxyanisole (BHA) mixed with ground chicken thigh meat. The raw meat was cooked, stored under refrigeration, and analyzed for lipid oxidation and total volatiles after 0, 4, and 8 days. In addition, cooked thigh meat patties were prepared separately for evaluation of specific sensory attributes. Generally, OEL2 was the most comparable additive to the synthetic E-250 regarding TBARS values. The total volatile (TV) profile showed that E-250 and OEL2 were the most effective at decreasing off odor volatiles (p < 0.05). Sensory data also revealed the greatest improvement in overall meat acceptability with the use of OEL2. The recommended level of OE in cooked chicken meat is approximately 250 ppm.
Natto is a fermented food made from soybeans using Bacillus subtilis natto. B. subtilis is present in honey. In this study, we evaluated the genetic and enzymatic characteristics of B. subtilis obtained from commercial honey and its suitability for natto fermentation. Three bacterial strains isolated from honey samples of different origins were found to be highly homologous to B. subtilis via 16S rDNA analysis. Similar to B. subtilis natto, all three isolates were biotin auxotrophs and possessed two insertion sequences. Genotyping by random amplified polymorphic DNA-polymerase chain reaction and enzyme activity analysis showed that the isolates were genetically different from the commonly used natto strains Miyagino, Takahashi, and Naruse. The three isolates are highly suitable for natto fermentation. These results indicate that honey is a source of B. subtilis natto that is potentially useful in the food industry.
The antiallergic activity of extracts of Naruto Kintoki sweet potato peel was enhanced after cooking the peel using three conventional methods. Using 400 µg/mL extracts, baking showed the highest suppression of β-hexosaminidase release (36.9%), followed by microwaving (41.9%) and boiling (64.2%). Significant suppression of β-hexosaminidase release from RBL-2H3 cells in response to Naruto Kintoki peel extract was attributed to compounds 9 (r = 0.91, p < 0.01) and 11 (r = 0.76, p < 0.05). UPLC/ESI-Q-TOF-MS analyses of compounds 5 and 8 clarified the existence of two sulfates of flavonol aglycones (3, 5, 3′-trihydroxy-7, 4′-dimethoxyflavone 3-O-sulfate and 3, 5-dihydroxy-7, 4′-dimethoxyflavone 3-O-sulfate). Baking the sweet potato peel changed compounds 5 and 8 to compounds 9 and 11 with enhanced antiallergic activity. Specifically, IC50 values changed from 11.0 µg/mL (5) to 4.1 µg/mL (9) and from 12.1 µg/mL (8) to 4.4 µg/mL (11). We found those four chemicals contributed to the observed antiallergic activity of Naruto Kintoki sweet potato peel extracts.