The contamination of fermented feeds and foods with fungi and mycotoxins is a major food safety issue worldwide. Certain lactic acid bacteria (LAB), generally recognized as safe (GRAS) fermentation probiotics, are able to reduce microbial and mycotoxins contamination. In this study, Lactiplantibacillus (L.) plantarum Q1-2 and L. salivarius Q27-2 with antifungal properties were screened as inoculants for mixed fermenting feed, and the fermentation and nutritional qualities, microbial community, and mycotoxins of mixed fermented feed were analyzed at different fermentation periods (1, 3, 7, 15, and 30 days, respectively). The findings indicated that the utilization of Q1-2 and Q27-2 strains in fermenting feed led to a decrease in pH and an increase in lactic acid concentration and the proportion of Lactiplantibacillus, while effectively restraining the proliferation of undesirable microorganisms. In particular, Q1-2 reduced the relative abundance of fungi including Fusarium and Aspergillus. Compared to the control group, the Q1-2 and Q27-2 groups reduced aflatoxin B1 by 34.17% and 16.57%, and deoxynivalenol by up to 90.61% and 51.03%. In short, these two LAB inoculants could reduce the contents of aflatoxin B1 and deoxynivalenol to the limited content levels stipulated by the Chinese National Standard GB 13078-2017. These findings suggest that the LAB strains of Q1-2 and Q27-2 have potential applications in the feed industry for the mitigation of mycotoxin pollution, thereby enhancing the quality of animal feed.
The antifungal activity of cinnamon (Cinnamomum cassia Presl), litsea [Litsea cubeba (Lour.) Pers.], clove (Syzygium aromaticum L.), thyme (Thymus mongolicus Ronn.) and citronella (Cymbopogon winterianus Jowitt) essential oils (EOs) against the dominant fungi isolated from moldy peanuts was investigated in this research. Firstly, strain YQM was isolated and identified by morphological characterization and 18S rRNA gene sequence analysis to be Aspergillus flavus (A. flavus). Next, antifungal effects of single or mixed EOs on strain YQM were evaluated by the inhibition zone test. The cinnamon-litsea combined essential oil (CLCEO, Vcinnamon oil:Vlitsea oil = 3:5) displayed the best antifungal effect on strain YQM. The chemical composition of CLCEO was identified and quantified by gas chromatograph-mass spectrometry (GC-MS), and results revealed that the major components of CLCEO were cinnamaldehyde and citral. Finally, the effect of EOs on the microstructure of strain YQM mycelia was observed under scanning electron microscope (SEM). The mycelia exposed to cinnamon essential oil (CEO) and litsea essential oil (LEO) were partly deformed and collapsed, while the mycelia treated with CLCEO were seriously damaged and the deformation phenomena such as shrinking, shriveling and sinking occurred. Therefore, CLCEO has great potential for using as anti-mildew agents during peanut storage.
Proanthocyanidins are important compounds known for their antioxidant and radical scavenging properties, but they are highly sensitive to light, heat, oxygen, and pH. In our study, proanthocyanidin was encapsulated using sodium alginate and carboxymethyl cellulose to enhance controlled release, pH stability, metal ion tolerance, temperature resistance, time release, the microencapsulation of food additives stability, antioxidant capacity analysis, and the storage period tolerance of proanthocyanidin. Fourier transforms infrared (FTIR) analysis and full-wavelength UV scanning indicated the successful immobilization of proanthocyanidins into the polymeric microcapsules. The flowability and mechanical properties of the microcapsules were enhanced. Moreover, proanthocyanidin microcapsules exhibited higher thermal, pH, metal ion, time, and microencapsulation food additive stability. In addition, due to their high antioxidant properties, the proanthocyanidin microcapsules retained a greater amount of proanthocyanidin content during the gastric phase, and the proanthocyanidin was subsequently released in the intestinal phase for absorption. Thus, the study provided a systematic understanding of the antioxidant capabilities and stability of proanthocyanidin microcapsules, which is beneficial for developing preservation methods for food additives.
Low temperatures are an effective way of delaying grain rancidity and deterioration. However, little is known about the difference in quality changes in high-moisture japonica brown rice at different storage temperatures. In this study, the storage quality changes in japonica brown rice with a 15.50% moisture content stored at 15 °C, 20 °C, and 25 °C were investigated. In addition, an untargeted lipidomics analysis coupled with gas chromatography and mass spectrometry (GC-MS) was applied to analyze the volatile compounds and metabolite changes in the high-moisture japonica brown rice. The results showed that storage at 15 °C could well maintain the color and aroma stability of the brown rice and delay the increase in fatty acid value (FAV). The lipidomics results showed that storage at 15 °C delayed glycerolipid and sphingolipid metabolism and reduced glycerophospholipid catabolism in the brown rice. The low-temperature environment regulated these three metabolic pathways to maintain higher contents of triglycerides (TG), phosphatidylserine (PS), abd phosphatidylethanolamine (PE), and lower contents of diglycerides (DG), OAcyl-(gamma-hydroxy) FA (OAHFA), ceramides (Cer), and glycosylceramides (Hex1Cer) in the high-moisture japonica brown rice, which maintained the storage stability of the brown rice. Our results proposed the cryoprotection mechanism of postharvest brown rice from the perspective of volatile compounds and metabolite changes, providing a foothold for the further exploration of low-temperature storage as a safe and efficient cryoprotectant in the grain storage field.