Simultaneously enhanced stability and biological activities of chlorogenic acid by covalent grafting with soluble oat ß-glucan.

Chlorogenic acid (CA) has a wide range of biological activities but the chemical structure is extremely unstable. In this study, CA was grafted onto a soluble oat ß-glucan (OßGH) to improve the stability. Although the crystallinity and thermal stability of CA-OßGH conjugates reduced, the storage stability of CA significantly improved. The DPPH and ABTS scavenging ability of CA-OßGH IV (graft ratio 285.3 mg CA/g) were higher than 90 %, which is closed to activities of equivalent concentration of Vc (93.42 %) and CA (90.81 %). The antibacterial abilities of CA-OßGH conjugates are improved compared to the equivalent content of CA and potassium sorbate. Particularly, the inhibition rate of CA-OßGH for gram-positive bacteria (Staphylococcus aureus and Listeria monocytogenes) are significantly higher than that of gram-negative bacteria (Escherichia coli). The results demonstrated that covalent grafted CA with soluble polysaccharide is an effective strategy to enhance its stability and biological activities.

The combined effect of protein hydrolysis and Lactobacillus plantarum fermentation on antioxidant activity and metabolomic profiles of quinoa beverage.

Lactic acid bacteria fermentation is a commonly applied technique to produce nutritional, functional, and organoleptic enhanced foods. In the present study, protein hydrolysis and Lactobacillus plantarum fermentation were coupled to develop quinoa beverages. Protein hydrolysis effectively promoted the growth and fermentation of L. plantarum. Fermentation alone did not significantly improve antioxidant activity, but the combined use of protein hydrolysis and L. plantarum fermentation significantly improved the antioxidant activity of the quinoa beverage. Nontargeted metabolomics based on UHPLC-Q Exactive HF-X/MS and multivariate statistical analysis were performed to reveal the metabolite profile alterations of the quinoa beverage by different processing methods. A total of 756 metabolites were identified and annotated, which could be categorized into 12 different classes. The significant differentially abundant metabolites were mainly involved in primary metabolite metabolism and secondary metabolite biosynthesis. Many of these metabolites were proven to be vitally important to the function and taste formation of the quinoa beverage. Most importantly, the coupled use of protein hydrolysis and L. plantarum fermentation significantly increased some functional ingredients compared with protein hydrolysis and L. plantarum fermentation alone. The above results indicate that protein hydrolysis coupled with L. plantarum fermentation is an effective strategy to develop functional quinoa beverages.

The Efficiency of Lemon Essential Oil-Based Nanoemulsions on the Inhibition of Phomopsis sp. and Reduction of Postharvest Decay of Kiwifruit.

Essential oils (EOs) have excellent antibacterial activity and are generally recognized as safe (GRAS) for use in food preservatives. However, the application of EOs is limited because of their strong volatility and easily oxidized. Encapsulation of EOs into nanoemulsions could effectively prevent oxidative deterioration. In this study, lemon essential oil-based nanoemulsion (LEO/NE) was prepared by high-pressure homogenization. FT-IR and encapsulation efficiency analysis indicated that LEO was effectively encapsulated in the nanoemulsion. The results of zeta potential changes after 35 d storage indicated that LEO/NE exhibits good stability at room temperature. The effect of LEO/NE on the main soft rot pathogens of kiwifruit Phomopsis sp. was investigated, and the results showed that LEO/NE significantly inhibited spore germination and mycelia growth of Phomopsis sp. by promoting ROS accumulation, intracellular antioxidant enzyme activities, and cell apoptosis. The preservation experiment was carried out by inoculating Phomopsis sp. spores into fresh kiwifruit, and the LEO/NE effectively inhibited soft rot development in kiwifruit in a LEO dose dependent manner. LEO/NE with 1% LEO loading amount has a good effect on preventing postharvest decay of kiwifruit caused by Phomopsis sp.

Preparation and characterization of feruloylated oat ß-glucan with antioxidant activity and colon-targeted delivery.

Ferulic acid (FA) is an effective chemopreventive and therapeutic agent for colorectal cancer. However, FA cannot stably reach the colon through human digestive system, and it can be grafted into oligosaccharides to improve its digestion stability. Therefore, in this study, different degrees of substitution of feruloylated oat ß-glucan (FA-OßG) were prepared by grafting FA onto water soluble oat ß-glucan. FA grafting changed the crystallinity and surface morphology of OßG, and the thermal stability of the FA-OßG improved. As the DS increased, the antioxidant activity of FA-OßG increased, and FA-OßG III with DS of 0.184 showed the same antioxidant activities compared to the equal amount of free FA. The FA-OßG showed higher stability under gastrointestinal and colonic conditions than free FA. Furthermore, the FA-OßG conjugates exhibited good in vitro anticancer activity against human colorectal cancer cells, while FA-OßG III showed better anticancer activity than an equal amount of free FA.