Effects of lactic acid bacteria on antioxidant activity in vitro and aroma component of Eucommia ulmoides tea.

Eucommia ulmoides tea is a popular functional health drink in Asian countries, but its unique herbal aroma is difficult for consumers to accept. The effects of four lactic acid bacteria strains (Lactobacillus plantarium, Lactobacillus bulgaricus, Lactobacillus acidophilus and Streptococcus thermophilus) fermentation on the physicochemical property, antioxidant activity in vitro and aroma component of E. ulmoides leaves were studied. Within the four strains, the sample by L. bulgaricus fermentation showed the higher concentrations of chlorogenic acid, geniposidic acid and stronger antioxidant activity in vitro. Moreover, the sample by L. bulgaricus fermentation produced a stronger fruity and floral flavor. These results suggested that L. bulgaricus was the best strain for fermentation E. ulmoides tea. The differences between different strains should be considered when selecting lactic acid bacteria for raw material fermentation of fruits and vegetables.

Wounding induces suberin deposition, relevant gene expressions and changes of endogenous phytohormones in Chinese yam (Dioscorea opposita) tubers.

Wounds on Chinese yam (Dioscorea opposita ) tubers can ocurr during harvest and handling, and rapid suberisation of the wound is required to prevent pathogenic infection and desiccation. However, little is known about the causal relationship among suberin deposition, relevant gene expressions and endogenous phytohormones levels in response to wounding. In this study, the effect of wounding on phytohormones levels and the expression profiles of specific genes involved in wound-induced suberisation were determined. Wounding rapidly increased the expression levels of genes, including PAL , C4H , 4CL , POD , KCSs , FARs , CYP86A1 , CYP86B1 , GPATs , ABCGs and GELPs , which likely involved in the biosynthesis, transport and polymerisation of suberin monomers, ultimately leading to suberin deposition. Wounding induced phenolics biosynthesis and being polymerised into suberin poly(phenolics) (SPP) in advance of suberin poly(aliphatics) (SPA) accumulation. Specifically, rapid expression of genes (e.g. PAL , C4H , 4CL , POD ) associated with the biosynthesis and polymerisation of phenolics, in consistent with SPP accumulation 3days after wounding, followed by the massive accumulation of SPA and relevant gene expressions (e.g. KCSs , FARs , CYP86A1 /B1 , GPATs , ABCGs , GELPs ). Additionally, wound-induced abscisic acid (ABA) and jasmonic acid (JA) consistently correlated with suberin deposition and relevant gene expressions indicating that they might play a central role in regulating wound suberisation in yam tubers.

Comparison of calcium and ultrasonic treatment on fruit firmness, pectin composition and cell wall-related enzymes of postharvest apricot during storage.

This study was conducted to examine the effects of calcium treatment (2%, 20 min) and ultrasonic treatment (400 W, 20 min) on postharvest apricot fruit during storage. The results showed that after calcium and ultrasonic treatment, compared with the control, the firmness of apricot fruit increased by 41.53% and 3.83% at 16 d, but juice yield and water-soluble pectin (WSP) content decreased by 8.26% and 3.55%, 28.57% and 4.08%, respectively. Both calcium and ultrasonic treatment were more effective in reducing polygalacturonase (PG), ß-Galactosidase (ß-Gal), pectin methylesterase (PME), polyphenol oxidase (PPO) and peroxidase (POD) activity. Moreover, fruit firmness was significantly negatively correlated with juice yield, WSP and PPO, and positively correlated with PG and ß-Gal, PPO and POD. In contrast, calcium treatment was more effective than ultrasonic treatment in delaying postharvest softening of apricot.

Effects of konjac glucomannan on the long-term retrogradation and shelf life of boiled wheat noodles.

BACKGROUND: Starch retrogradation and moisture migration of boiled wheat noodles (BWNs) result in quality deterioration and short shelf life. The objective of this research was to investigate whether konjac glucomannan (KGM) could improve the quality of BWNs and further establish the shelf-life prediction model. RESULTS: The moisture distribution, recrystallization, and thermal properties of BWNs during refrigerated or ambient temperature storage were determined. Low-field nuclear magnetic resonance data showed that KGM addition induced left-shifts of T21 and T22 values, indicating that KGM limited the mobility of bound and immobile water among noodle matrices. X-ray diffraction spectra revealed that KGM did not change the crystal patterns of BWNs but could inhibit the starch recrystallization after refrigerated storage. The Tp and ΔH values of retrograded samples notably (P < 0.05) decreased with the increase of KGM addition, suggesting the hinderance of starch retrogradation behavior by KGM. The shelf life of BWNs was predicted by accelerated storage test combined with the Arrhenius equation. The present data displayed that the predicted shelf life of vacuum-packed and sterilized BWNs with 10 g kg-1 KGM at 25 °C was 733 days, 2.4-fold that of the control group. CONCLUSION: BWNs with KGM addition could inhibit starch retrogradation and improve the storage stability, consequently promoting noodle quality. © 2021 Society of Chemical Industry.

Removal of Alternaria mycotoxins from aqueous solution by inactivated yeast powder.

BACKGROUND: Alternariol (AOH) and alternariol monomethyl ether (AME), produced by Alternaria spp., are the two mycotoxins with the highest outbreak rates in food systems. The purpose of this study was to investigate the removal of AOH and AME from aqueous solutions by inactivated yeast cells. The effects of strains, yeast powder amount, temperature, and pH were evaluated. The kinetics of AOH and AME adsorption on inactivated yeast cells was fitted with four models and a release assay was carried out. RESULTS: All three tested yeasts could remove AOH and AME. GIM 2.119 was the most effective strain. The reduction rate of both AOH and AME could be as much as 100% with 40 g‧L-1 of yeast powder. For both mycotoxins, pH = 9 was the best environment for toxin removal. The pseudo-second-order kinetic model was the best model, with R2 ranging from 0.989 to 0.999. However, the R2 of the pseudo-first-order and Elovich models was also relatively high. Alternariol and AME could be partially eluted by methanol and acetonitrile. CONCLUSION: The inactivated yeast cells could effectively remove AOH and AME. This was best fitted by the pseudo-second-order model. The release assay suggested that the adsorption of Alternaria mycotoxins was partially reversible. The results of this study provide a theoretical basis for the removal of Alternaria mycotoxins from food systems and are useful for the investigation of the mechanisms involved in mycotoxin adsorption by inactivated yeast cells. © 2020 Society of Chemical Industry.

Ultrasonic-assisted extraction and antioxidant activity of polysaccharides from Eucommia ulmoides leaf.

Eucommia ulmoides is valuable medicinal plant in China. In this study, ultrasonic technology was used to extract polysaccharides and orthogonal design was applied to choose the optimal extraction conditions. The optimal extraction conditions of E. ulmoides polysaccharides were made up of the ratio of water to raw 30, extraction time 80 min, extraction temperature 60°C and extraction power 200 W. Under these conditions, the extraction polysaccharides content reached 164.95 mg/g. In addition, the potential antioxidant activity of crude polysaccharides (Cp) and pure polysaccharides (Pp) was demonstrated by evaluating reducing power assay, DPPH radical-scavenging assay, OH radical-scavenging assay and ABTS radical-scavenging assay. The results showed that E. ulmoides polysaccharides had significantly impact on the scavenging of DPPH radicals, OH radicals and ABTS radicals, expecially in DPPH radicals with an IC50 values of 0.005 mg/mL and 0.011 mg/mL in Cp and Pp, respectively. However, they were less effective in reducing power assay with low IC50 values of 1.091 mg/mL and 1.041 mg/mL separately. These results indicated that polysaccharides from E. ulmoides leaf could be applied as potential antioxidant.

Comparative Phytonutrient Analysis of Broccoli By-Products: The Potentials for Broccoli By-Product Utilization.

The phytonutrient concentrations of broccoli (Brassica oleracea var. italica) florets, stems, and leaves were compared to evaluate the value of stem and leaf by-products as a source of valuable nutrients. Primary metabolites, including amino acids, organic acids, and sugars, as well as glucosinolates, carotenoids, chlorophylls, vitamins E and K, essential mineral elements, total phenolic content, antioxidant activity, and expression of glucosinolate biosynthesis and hydrolysis genes were quantified from the different broccoli tissues. Broccoli florets had higher concentrations of amino acids, glucoraphanin, and neoglucobrassicin compared to other tissues, whereas leaves were higher in carotenoids, chlorophylls, vitamins E and K, total phenolic content, and antioxidant activity. Leaves were also good sources of calcium and manganese compared to other tissues. Stems had the lowest nitrile formation from glucosinolate. Each tissue exhibited specific core gene expression profiles supporting glucosinolate metabolism, with different gene homologs expressed in florets, stems, and leaves, which suggests that tissue-specific pathways function to support primary and secondary metabolic pathways in broccoli. This comprehensive nutrient and bioactive compound profile represents a useful resource for the evaluation of broccoli by-product utilization in the human diet, and as feedstocks for bioactive compounds for industry.

Ultrasound enhances calcium absorption of jujube fruit by regulating the cellular calcium distribution and metabolism of cell wall polysaccharides.

BACKGROUND: Ultrasound has been applied in fruit pre-washing processes. However, it is not sufficient to protect fruit from pathogenic infection throughout the entire storage period, and sometimes ultrasound causes tissue damage. The goal of this study was to investigate the effects of calcium chloride (CaCl2 , 10 g L-1 ) and ultrasound (350 W at 40 kHz), separately and in combination, on jujube fruit quality, antioxidant status, tissue Ca2+ content and distribution along with cell wall metabolism at 20 °C for 6 days. RESULTS: All three treatments significantly maintained fruit firmness and peel color, reduced respiration rate, decay incidence, superoxide anion, hydrogen peroxide and malondialdehyde and preserved higher enzymatic (superoxide dismutase, catalase and peroxidase) and non-enzymatic (ascorbic acid and glutathione) antioxidants compared with the control. Moreover, the combined treatment was more effective in increasing tissue Ca2+ content and distribution, inhibiting the generation of water-soluble and CDTA-soluble pectin fractions, delaying the solubilization of Na2 CO3 -soluble pectin and having lower activities of cell wall-modifying enzymes (polygalacturonase and pectate lyase) during storage. CONCLUSION: These results demonstrated that the combination of CaCl2 and ultrasound has potential commercial application to extend the shelf life of jujube fruit by facilitating Ca2+ absorption and stabilizing the cell wall structure. © 2017 Society of Chemical Industry.