Developing a High-Umami, Low-Salt Soy Sauce through Accelerated Moromi Fermentation with Corynebacterium and Lactiplantibacillus Strains.

The traditional fermentation process of soy sauce employs a hyperhaline model and has a long fermentation period. A hyperhaline model can improve fermentation speed, but easily leads to the contamination of miscellaneous bacteria and fermentation failure. In this study, after the conventional koji and moromi fermentation, the fermentation broth was pasteurized and diluted, and then inoculated with three selected microorganisms including Corynebacterium glutamicum, Corynebacterium ammoniagenes, and Lactiplantibacillus plantarum for secondary fermentation. During this ten-day fermentation, the pH, free amino acids, organic acids, nucleotide acids, fatty acids, and volatile compounds were analyzed. The fermentation group inoculated with C. glutamicum accumulated the high content of amino acid nitrogen of 0.92 g/100 mL and glutamic acid of 509.4 mg/100 mL. The C. ammoniagenes group and L. plantarum group were rich in nucleotide and organic acid, respectively. The fermentation group inoculated with three microorganisms exhibited the best sensory attributes, showing the potential to develop a suitable fermentation method. The brewing speed of the proposed process in this study was faster than that of the traditional method, and the umami substances could be significantly accumulated in this low-salt fermented model (7% w/v NaCl). This study provides a reference for the low-salt and rapid fermentation of seasoning.

Unlocking the Potential of Microwave Sterilization Technology in Ready-to-Eat Imitation Crab Meat Production.

Microwave sterilization is a novel potential sterilization technology to improve food quality. An industrial microwave sterilization system was used to sterilize imitation crab meat under thermal processing intensity F0 = 1, 2, 3. The characteristics of the microwave process, such as heating rate, processing time, and C100, were calculated. In addition, the quality of processed imitation crab meat was investigated. Compared with the conventional retort method, microwave sterilization significantly shortened the processing time of imitation crab meat by 63.71% to 72.45%. Under the same thermal processing intensity, microwave sterilization has demonstrated better results than retort sterilization in terms of water-holding capacity, color, and texture. Furthermore, microwave-treated imitation crab meat ingredients had a greater capacity to bind water molecules and obtained a more appropriate secondary protein structure. In addition, microwave technology can better preserve the unsaturated fatty acids (UFA) of imitation crab meat, which are 9.14%, 1.19%, and 0.32% higher than the traditional method at F0 = 1, 2, 3. The results would provide useful data for the subsequent research and development of ready-to-eat surimi products.

New Insights into the Loss of Antioxidant Effectiveness of Phenolic Compounds in Vegetable Oils in the Presence of Phosphatidylcholine.

It has been proposed that lipid oxidation reactions in edible oils primarily occur in reverse micelles (RM) of amphiphilic components. While the prooxidative effect of RM has been demonstrated, the mechanism involved is not fully understood. Both reductions and enhancements in the antioxidant efficacy (AE) of α-tocopherol and Trolox have been observed in different studies when phosphatidylcholine (PC) was added and PC RM were formed. However, most of these investigations employed lipid systems consisting of stripped vegetable oil diluted in saturated medium-chain triacylglycerols (MCT) and utilized antioxidant concentrations well below those found in edible oils. These two specific factors were investigated in the present study. The effect of RM of purified egg yolk PC on the AE of 1.16 mmol kg-1 α-tocopherol or Trolox in stripped sunflower oil (SSO) was studied by the Rancimat (100 °C) and oven (50 °C) tests. Increasing PC concentrations (50-1000 ppm) had no significant impact on α-tocopherol, but substantial reductions in AE were observed for Trolox. This phenomenon may be attributed to the partitioning of Trolox into the pre-existing PC micelles, suggesting that primary oxidation reactions occurred in the continuous lipid phase. In addition, the effectiveness of both antioxidants decreased significantly in the presence of PC when a low antioxidant concentration (0.06 mmol kg-1) was assayed in SSO:MCT (1:3, w/w).

Effects of cooling rates during depuration on the quality of Pacific oysters (Crassostrea gigas) at anhydrous preservation stage.

The Pacific oyster could be affected by several pressure sources during cold chain logistics, which reduce the quality of oyster, and even improve its mortality. For improving the quality of oyster, the effects of depuration process at different cooling rates (1, 3, 7, 11 and 16 °C/h) on selected Pacific oyster were studied. The results indicated that extreme fluctuations in the depuration temperatures could affect the survival rates and qualities of oysters. The oysters exhibited low survival rates, glycogen contents and pH values at an increased cooling rate. Their contents in the 1 °C/h group after 3 d preservation were 100 %, 16.30 ± 1.64 mg/100 g and 6.72 ± 0.01, respectively, while there were 71 %, 7.72 ± 0.88 mg/100 g and 6.53 ± 0.01 in the 16 °C/h group after 3 d preservation, respectively. Furthermore, the ATP-related compounds were affected by the different cooling rates. AMP and IMP were the main ATP-related compounds, and their contents in the 1 °C/h group after 3 d preservation were 37.21 ± 1.10 mg/100 g and 29.47 ± 1.10 mg/100 g, respectively, while there were 32.07 ± 1.10 mg/100 g and 13.16 ± 1.60 mg/100 g in the 16 °C/h group after 3 d preservation, respectively. The proportions of the total umami, as well as the sweet amino acids also decreased, the proportions of the umami amino acids and sweet amino acids in the total amino acids, were 31.37%-38.80%, and their proportions in 1 °C/h group were higher than that in 16 °C/h group. Conversely, the fatty acid content of each group exhibited significant differences. Combined with the above results, the oyster maintained a high survival rate and higher quality at a cooling rate of 1 °C/h during depuration.

A chemometric study on the identification of 5-methylfurfural and 2-acetylfuran as particular volatile compounds of oxidized fish oil based on SHS-GC-IMS.

Fish oil develops particular off-odors, mainly fishy odor, from the oxidation of its characteristic fatty acids, docosahexaenoic (DHA) and eicosapentaenoic (EPA). Anchovy oil (AO) was taken as representative of fish oils. This was compared to three vegetable oils with different fatty acid compositions, i.e. camellia, sunflower and linseed oil, and differential volatile compounds were identified by static-headspace gas-chromatography ion-mobility-spectrometry (SHS-GC-IMS) and orthogonal partial-least-squares discriminant analysis (OPLS-DA) during oxidation at 60 °C. Three groups of differential volatile compounds detected at higher concentrations in the AO were screened out and two compounds, identified as 5-methylfurfural and 2-acetylfuran, were characteristic to the AO and not found in the vegetable oils. They were formed from both EPA and DHA, only present in the AO, and their formation mechanisms were proposed. The contents of 5-methylfurfural and 2-acetylfuran increased linearly with the oxidation time and consequently they could be used as oxidative markers of fish oils.

Concomitant oxidation of fatty acids other than DHA and EPA plays a role in the characteristic off-odor of fish oil.

The aim of the present research was to explore the development of off-odors in fish oil from the perspective of fatty acid oxidation. It was found that the off-odors elicited by the two major ω-3 PUFAs in fish oil, i.e. DHA and EPA, were different from those by fish oil. Results showed that simultaneous oxidation of fatty acids other than DHA and EPA can be involved. The off-odors of fish oil was successfully simulated by combining oxidized samples of DHA, EPA and sunflower oil. Therefore, oxidation of oleic and linoleic acids also contributed to the off-odors in fish oil. A novel analytical approach that consisted in the combination of gas chromatography-ion mobility spectrometry (GC-IMS) and orthogonal partial least squares discriminant analysis (OPLS-DA) was applied to identify differences in the volatile components between the recombinant oil and the fish oil.

Assessing the Impact of Oil Types and Grades on Tocopherol and Tocotrienol Contents in Vegetable Oils with Chemometric Methods.

The consumption of vegetable oil is an important way for the body to obtain tocols. However, the impact of oil types and grades on the tocopherol and tocotrienol contents in vegetable oils is unclear. In this study, nine types of traditional edible oils and ten types of self-produced new types of vegetable oil were used to analyze eight kinds of tocols. The results showed that the oil types exerted a great impact on the tocol content of traditional edible oils. Soybean oils, corn oils, and rapeseed oils all could be well distinguished from sunflower oils. Both sunflower oils and cotton seed oils showed major differences from camellia oils as well as sesame oils. Among them, rice bran oils contained the most abundant types of tocols. New types of oil, especially sacha inchi oil, have provided a new approach to obtaining oils with a high tocol content. Oil refinement leads to the loss of tocols in vegetable oil, and the degree of oil refinement determines the oil grade. However, the oil grade could not imply the final tocol content in oil from market. This study could be beneficial for the oil industry and dietary nutrition.

Effect of Stored Humidity and Initial Moisture Content on the Qualities and Mycotoxin Levels of Maize Germ and Its Processing Products.

With high fat and protein content, maize germ is easily infected with fungus and mycotoxins during its storage. The qualities and safety of germ and its processing products may be affected by the storage. However, studies on the effect of storage on quality and polluted mycotoxin level of maize germ are limited. In this study, maize germ was stored with different initial moisture contents (5.03, 9.07, 11.82 and 17.97%) or at different relative humidity (75, 85 and 95%) for 30 days. The quality indices of germ (moisture content and crude fat content) and their produced germ oils (color, acid value and peroxide value) as well as the zearalenone (ZEN) and deoxynivalenol (DON) levels of germ, oils and meals were analyzed. Results showed that maize germ with high initial moisture contents (11.82, 17.97%) or kept at high humidity (95%) became badly moldy at the end of storage. Meanwhile, the qualities of these germ and oils showed great changes. However, the ZEN and DON contents of this maize germ, oils and meals stayed at similar levels (p < 0.05). Therefore, the storage could produce influence on the qualities of germ and oils, but showed limited effect on the DON and ZEN levels of germ and their processing products. According to this study, the storage condition of germ with no more than 9% moisture content and no higher than 75% humidity was recommended. This study would be benefit for the control of germ qualities and safety during its storage.

Application of Plackett-Burman Design in Screening of Natural Antioxidants Suitable for Anchovy Oil.

Considering the safety of synthetic antioxidants, more and more natural antioxidants have been developed and utilized in foods. This study aimed to screen out a natural antioxidant combination from many antioxidants, which could significantly affect the oxidation stability of anchovy oil, while Plackett-Burman design (PBD) methodology was employed in this screening. According to the statistical results of this design, sesamol, dihydromyricetin, teapolyphenol, and rosemary acid were four significant parameters on the oxidation stability of anchovy oil. Moreover, dihydromyricetin presented the best antioxidant effect among nine kinds of selected antioxidants when they were used alone in anchovy oil. Meanwhile, a combination including sesamol (0.02%), teapolyphenol (0.02%). and rosemary acid (0.02%) was adopted, and its antioxidant ability was similar to that of tert-butylhydroquinone (TBHQ). Additionally, phytic acid as a synergist was used and combined with sesamol, and the antioxidant ability of this combination was better than that of TBHQ. This study presented a reference for the industrial applications of natural antioxidants and synergists in anchovy oil.

Occurrence of deoxynivalenol in maize germs from North China Plain and the distribution of deoxynivalenol in the processed products of maize germs.

69 maize germ samples from North China Plain, 40 processed products of maize germs obtained in lab, 30 crude corn oils from factories and 40 refined corn oils from supermarkets in China were analyzed of deoxynivalenol (DON) by HPLC combined with ultraviolet detection and immunoaffinity column. 95.7% of maize germs were contaminated by DON. The average content was 449.0 µg/kg. The average of DON in processed products of maize germs including solvent extracted oil, cold-press oil, meal and cake was 163.7, 113.1, 1111.5 and 1175.2 µg/kg, respectively. Only 20% of crude corn oil and 12.5% of refined corn oil were contaminated by DON with the range of 67.5-340.5 µg/kg and 57.1-207.5 µg/kg, respectively. During the production of corn oil, solvent extraction oil had a larger amount of DON than pressing oil. The contamination of DON in corn oil was not serious or widespread, which indicated a low risk of health.

Occurrence of polycyclic aromatic hydrocarbons in various types of raw oilseeds from different regions of China.

Ninety-five samples of 18 types of oilseeds used for edible oil production were collected from different origins of China. The occurrence of polycyclic aromatic hydrocarbons (PAHs) in these oilseeds was presented after the analysis by using a simplified gas chromatography-mass spectrometry method. The results indicated that some of these oilseeds were not found of indeno[1,2,3-cd]pyrene, dibenz[a,h]anthracene, and benzo[ghi]perylene. Naphthalene and phenanthrene had higher concentration than other individual PAH in the same sample. The range of BaP, PAH4, and PAH16 concentration in these 95 samples was 0.1-14.1, 1.1-74.6, and 81.8-466.8 µg/kg, respectively. LPAH accounted for 87.1-99.5% of the total concentration of PAHs in all of studied oilseeds. The average concentrations of PAH16 in different types of oilseed were different. Meanwhile, the samples collected from different origins of China presented various levels of PAH16. The differences between herbaceous plant oilseeds and woody plant oilseeds in terms of PAH levels were not observed.