Effect of Phenolic Acid on Antioxidant Activity of Wine and Inhibition of Pectin Methyl Esterase

Beer production potentiality of some non-Saccharomyces yeast obtained from a traditional beer starter emao

The recent realisation regarding the potentiality of the long-neglected non-Saccharomyces yeasts in improving the flavour profile and functionality of alcoholic beverages has pushed researchers to search for such potent strains in many sources. We studied the fungal diversity and the rice beer production capability of the fungal strains isolated from emao-a traditional rice beer starter culture of the Boro community. Fifty distinct colonies were picked from mixed-culture plates, of which ten representative morphotypes were selected for species identification, and simultaneous saccharification and beer fermentation (SSBF) assay. The representative isolates were identified as Hyphopichia burtonii (Hbur-FI38, Hbur-FI44, Hbur-FI47 & Hbur-FI68), Saccharomyces cerevisiae (Scer-FI51), Wickerhamomyces anomalus (Wano-FI52), Candida carpophila (Ccar-FI53), Mucor circinelloides (Mcir-FI60), and Saccharomycopsis malanga (Smal-FI77 and Smal-FI84). The non-Saccharomyces yeast strains Hbur-FI38, Hbur-FI44, Ccar-FI53, and Smal-FI77 showed SSBF capacity on rice substrate producing beer that contained 7-10% (v/v) ethanol. A scaled-up fermentation assay was performed to assess the strain-wise fermentation behaviour in large-scale production. The nutritional, functional, and sensory qualities of the SSBF strain fermented beer were compared to the beer produced by emao. All the strains produced beer with reduced alcohol and energy value while compared to the traditional starter emao. Beer produced by both the strains of H. burtonii stood out with higher ascorbic acid, phenol, and antioxidant property, and improved sensory profile in addition to reduced alcohol and energy value. Such SSBF strains are advantageous over the non-SSBF S. cerevisiae strains as the former can be used for direct beer production from rice substrates.

Enhancing the oxidative stability of algal oil powders stabilized by egg yolk granules/lecithin composites

This study reported a powder formulation containing omega-3-rich algal oil emulsions stabilized by egg yolk granules (EYGs)/lecithin composites. The improved physical stability of the algal oil samples due to increasing pH and lecithin addition was beneficial to the oxidative stability through analysis of free radical scavenging activities, metal ion chelating activities, and the release of primary and secondary oxidation products during accelerated storage (12 days, 60 °C). In addition, the effect of three antioxidants, i.e. ascorbic acid (VC), ascorbyl palmitate (AP), and α-tocopherol (VE), on lipid oxidation was investigated. Results showed that antioxidant partitioning at different regions of the emulsion system influenced its ability to prevent oxidation with the effectiveness of AP (at the O/W interface) > VE (in the oil phase) > VC (in the aqueous phase). This study developed a new powder-based emulsion formulation for algal oils with superior oxidative stability as an alternative source of omega-3.

Characterization of the pectin methyl-esterase gene family and its function in controlling pollen tube growth in pear (Pyrus bretschneideri)

Pectin methyl-esterases (PMEs) play crucial roles in plant growth. In this study, we identified 81 PbrPMEs in pear. Whole-genome duplication and purifying selection drove the evolution of PbrPME gene family. The expression of 47 PbrPMEs was detected in pear pollen tube, which were assigned to 13 clusters by an expression tendency analysis. One of the 13 clusters presented opposite expression trends towards the changes of methyl-esterified pectins at the apical cell wall. PbrPMEs were localized in the cytoplasm and plasma membrane. Repression of PbrPME11, PbrPME44, and PbrPME59 resulted in the inhibition of pear pollen tube growth and abnormal deposition of methyl-esterified pectins at pollen tube tip. Pharmacological analysis confirmed that reduced PbrPME activities repressed the pollen tube growth. Overall, we have explored the evolutionary characteristics of PbrPME gene family and found the key PbrPME genes that control the growth of pollen tube, which deepened the understanding of pear fertility regulation.

Complex Tannins Isolated from Jelly Fig Achenes Affect Pectin Gelation through Non-Specific Inhibitory Effect on Pectin Methylesterase

Jelly fig (Ficus awkeotsang Makino) is used to prepare drinks and desserts in Asia, owing to the gelling capability of its pectin via endogenous pectin methylesterase (PE) catalyzation. Meanwhile, substances with PE inhibitory activity (SPEI) in jelly fig achenes (JFA) residue were noticed to be able to impede the gelation. In this study, we characterized and isolated SPEI from JFA by a series of PE inhibition-guided isolations. Crude aqueous extract of JFA residue was mixed with acetone, and 90% acetone-soluble matter was further fractionated by Diaion HP-20 chromatography. The retained fraction with dominant PE inhibitory activity was collected from 100% methanol eluate. Results from high-performance liquid chromatography mass spectrometry (HPLC/MS) and hydrolysis-induced chromogenic transition revealed the SPEI as complex tannins. Total tannins content was determined in each isolated fraction, and was closely related to PE inhibitory activity. In addition, SPEI in this study could inhibit activities of digestive enzymes in vitro and may, therefore, be assumed to act as non-specific protein binding agent.

Antioxidant activity and emulsion-stabilizing effect of pectic enzyme treated pectin in soy protein isolate-stabilized oil/water emulsion

The antioxidant activity of pectic enzyme treated pectin (PET-pectin) prepared from citrus pectin by enzymatic hydrolysis and its potential use as a stabilizer and an antioxidant for soy protein isolate (SPI)-stabilized oil in water (O/W) emulsion were investigated. Trolox equivalent antioxidant capacity (TEAC) was found to be positively associated with molecular weight (M(w)) of PET-pectin and negatively associated with degree of esterification (DE) of PET-pectin. PET-pectin (1 kDa and 11.6% DE) prepared from citrus pectin after 24 h of hydrolysis by commercial pectic enzyme produced by Aspergillus niger expressed higher α,α-diphenyl-β-picrylhydrazyl (DPPH) radical scavenging activity, TEAC, and reducing power than untreated citrus pectin (353 kDa and 60% DE). The addition of PET-pectin could increase both emulsifying activity (EA) and emulsion stability (ES) of SPI-stabilized O/W emulsion. When the SPI-stabilized lipid droplet was coated with the mixture of PET-pectin and pectin, the EA and ES of the emulsion were improved more than they were when the lipid droplet was coated with either pectin or PET-pectin alone. The amount of secondary oxidation products (thiobarbituric acid reactive substances) produced in the emulsion prepared with the mixture of SPI and PET-pectin was less than the amount produced in the emulsion prepared with either SPI or SPI/pectin. These results suggest that PET-pectin has an emulsion-stabilizing effect and lipid oxidation inhibition ability on SPI-stabilized emulsion. Therefore, PET-pectin can be used as a stabilizer as well as an antioxidant in plant origin in SPI-stabilized O/W emulsion and thus prolong the shelf life of food emulsion.

Preparation of antioxidant enzymatic hydrolysates from honeybee-collected pollen using plant enzymes

Enzymatic hydrolysates of honeybee-collected pollen were prepared using food-grade proteinase and aminopeptidases entirely of plant origin. Bromelain from pineapple stem was applied (8 mAU/g substrate) in the first hydrolysis stage. Aminopeptidase (0.05 U/g substrate) and proline iminopeptidase (0.03 U/g substrate) from cabbage leaves (Brassica oleracea var. capitata), and aminopeptidase (0.2 U/g substrate) from chick-pea cotyledons (Cicer arietinum L.) were involved in the additional hydrolysis of the peptide mixtures. The degree of hydrolysis (DH), total phenolic contents, and protein contents of these hydrolysates were as follows: DH (about 20–28%), total phenolics (15.3–27.2 μg/mg sample powder), and proteins (162.7–242.8 μg/mg sample powder), respectively. The hydrolysates possessed high antiradical scavenging activity determined with DPPH (42–46% inhibition). The prepared hydrolysates of bee-collected flower pollen may be regarded as effective natural and functional dietary food supplements due to their remarkable content of polyphenol substances and significant radical-scavenging capacity with special regard to their nutritional-physiological implications.