Combination of mutagenesis and adaptive evolution to engineer salt‐tolerant and aroma‐producing yeast for soy sauce fermentation

Abstract

BACKGROUND The moromi fermentation of high‐salt liquid‐state fermentation (HLF) soy sauce is usually performed in high‐brine solution (17–20%, w/w), which decreases the metabolic activity of aroma‐producing yeast. To enhance the soy sauce flavors, increasing the salt tolerance of aroma‐producing yeasts is very important for HLF soy sauce fermentation. RESULTS In the present study, atmospheric and room‐temperature plasma (ARTP) was first used to mutate the aroma‐producing yeast Wickerhamomyces anomalus, and the salt tolerant strains were obtained by selection of synthetic medium with a sodium chloride concentration of 18% (w/w). Furthermore, adaptive laboratory evolution (ALE) was used to improve the salt tolerance of the mutant strains. The results obtained indicated that the combination use of ARTP and ALE markedly increased the NaCl tolerance of the yeast by increasing the cellular accumulation of K+ and removal of cytosolic Na+, in addition to promoting the production of glycerin and strengthening the integrity of the cell membrane and cell wall. In soy sauce fermentation, the engineered strains improved the physicochemical parameters of HLF soy sauce compared to those produced by the wild‐type strain, and the engineered strains also increased the alcohol, acid and aldehyde production, and enriched the types of esters in the soy sauce. CONCLUSION The results of the present study indicated that the combination of ARTP mutagenesis and ALE significantly improved the salt tolerance of the aroma‐producing yeast, and also enhanced the production of volatiles of HLF soy sauce. © 2021 Society of Chemical Industry

Effect of cooking methods on the edible, nutritive qualities and volatile flavor compounds of rabbit meat

“…The volatile compounds were analyzed using gas chromatography‐mass spectrometry (GC‐MS, 7890A‐5975C; Agilent Technologies) coupled with an HP‐5MS UI column (30 m × 0.25 mm, 0.25 μm) 21,22 . Helium was used as the carrier gas at a flow rate of 1.0 mL min −1 with no split.…”

“…The detected aldehyde content was high in all seven samples, which is similar to many studies on meat flavor. 1 The PRS showed the most volatile components, with a total of 36, while the flavor components of the RRS (25) and FRS (22) were the least volatile. However, the RRS had the highest amount of volatile flavor compounds (50.30 μg kg −1 ), while the FRS had the lowest amount (21.49 μg kg −1 ).…”

“…The volatile compounds were analyzed using gas chromatographymass spectrometry (GC-MS, 7890A-5975C; Agilent Technologies) coupled with an HP-5MS UI column (30 m × 0.25 mm, 0.25 μm). 21,22 Helium was used as the carrier gas at a flow rate of 1.0 mL min −1 with no split. The temperature was initially maintained at 40 °C for 1 min, increased at 3 °C min −1 to 85 °C and maintained for 3 min, increased at 3 °C min −1 to 105 °C and maintained for 2 min, increased at 12 °C min −1 to 165 °C, and then increased at 10 °C min −1 to 230 °C.…”

Encapsulation of Zanthoxylum bungeanum essential oil to enhance flavor stability and inhibit lipid oxidation of Chinese‐style sausage

“…Volatile compounds were detected by solid‐phase microextraction gas chromatography–mass spectrometry (SPME‐GC/MS) using the method described by Li et al 27 . with some modifications: the sausage was ground in a meat grinder, 3.0 g of the samples was weighed and put into vials with 15 mL of headspace, and 1.0 μL of 2,4,6‐trimethylpyridine (2.0 μg mL −1 ) was added as an internal standard.…”

“…Sustained release characteristics of volatile flavor compounds Volatile compounds were detected by solid-phase microextraction gas chromatography-mass spectrometry (SPME-GC/MS) using the method described by Li et al 27 with some modifications: the sausage was ground in a meat grinder, 3.0 g of the samples was weighed and put into vials with 15 mL of headspace, and 1.0 μL of 2,4,6-trimethylpyridine (2.0 μg mL −1 ) was added as an internal standard. The vial was equilibrated at 75 °C for 40 min, and the SPME fiber (50/30 μm CAR/PDMS/DVB extraction head, Supelco, Bellefonte, PA, USA) was exposed to the vial headspace for 20 min.…”