Xiaona Guo

The impact of germination on the characteristics of brown rice flour and starch

BACKGROUND In recent years, germinated brown rice as a functional food has received great attention with its improved sensory and nutritional properties. Particularly of interest are the high levels of γ-amino butyric acid (GABA) which can be obtained during germination. However, more studies are needed to fully understand the effect of germination on the physicochemical properties of brown rice. RESULT Germination altered the chemical composition of brown rice, resulting in an increase in reducing sugar and ash content, and a reduction in amylose. Solubility, paste viscosity, transition temperatures (T(o) , T(p) and T(c) ) and percentage of retrogradation (%Retrogradation) were decreased, while swelling power and turbidity were significantly increased. Scanning electron micrographs indicated that starch granules from germinated brown rice became smaller and less homogeneous. Moreover, germination shortened the chain length of amylopectin and amylose molecules. CONCLUSION This investigation provides information on changes in the characteristics of rice flour and rice starch during germination, leading to a better understanding on the chemistry of brown rice germination.

Anti-Tumor Activity of a Novel Protein Obtained from Tartary Buckwheat

TBWSP31 is a novel antitumor protein that was isolated from tartary buckwheat water-soluble extracts. The objective of this paper was to investigate the anti-proliferative effects of TBWSP31 on breast cancer Bcap37cells and to explore its possible mechanism. After treatment of Bcap37 cells with TBWSP31, typical apoptotic morphological changes were observed by inverted microscopy and scanning electron microscopy (SEM), such as detachment from the culture plate, change to a round shape, cell shrinkage, the absence of obvious microvilli, plasma membrane blebbing, and formation of apoptotic bodies. Cell-cycle analysis revealed that treatment with TBWSP31 resulted in a G0/G1 arrest and prevented the cells from growing from G0/G1 phase to S phase, which was most prominent at 48 h. The expression of bcl-2 and Fas were detected quantitatively by FCM, which showed that TBWSP31 induced-apoptosis may be involved with the participation of Fas and bcl-2. These results suggest that TBWSP31 is a potential antitumor compound and that apoptosis induced by TBWSP31 is a key antitumor mechanism.

Evaluation the quality characteristics of wheat flour and shelf-life of fresh noodles as affected by ozone treatment.

In this study, the effects of ozone treatment on the microorganism mortality in wheat flour and shelf-life of fresh noodles were investigated, as well as the physicochemical properties of wheat flour and textural qualities of cooked noodles. Results showed that the total plate count (TPC) can be largely reduced in wheat flour exposed to ozone gas for 30 min and 60 min. Whiteness of flour and noodle sheet, dough stability, and peak viscosity of wheat starch were all increased by ozone treatment. Free cysteine content in wheat flour was shown to decrease significantly (P<0.05) as the treatment time increased and remarkable protein aggregates were observed in both reduced and non-reduced SDS-PAGE patterns. In addition, ozone treated noodles were generally higher in firmness, springiness, and chewiness, while lower in adhesiveness. Microbial growth and darkening rate of fresh noodles made from ozone treated flour were delayed significantly.

Purification and characterization of the antitumor protein from chinese tartary buckwheat (Fagopyrum tataricum Gaertn.) water-soluble extracts

A novel antitumor protein, coded as TBWSP31, was isolated from tartary buckwheat water-soluble extracts and purified by DEAE-Sepharose Fast Flow anion exchange, Sephadex G-100 gel filtration, and Sephacryl S-200 gel filtration column chromatography. TBWSP31 was identified to a homogeneous fraction by native PAGE. The antitumor effect of TBWSP31 against human mammary cancer cell Bcap37 was measured by an MTT assay. TBWSP31 showed higher antitumor activity, and time- and concentration-dependent effects were observed. SDS-PAGE analysis showed that TBWSP31 is composed of a single polypeptide with an approximate molecular weight of 57 kDa. TBWSP31 was rich in Glx (Gln+Glu), Arg, and Asx (Asp+Asn) according to amino acid analysis. Secondary structural analysis by CD spectroscopy revealed that TBWSP31 has the following: alpha-helix (33.9%), beta-sheet (22.8%), beta-turn (11.3%), and random coil (32.0%).

Nutritional evaluation and antioxidant activity of sesame sprouts.

Sesame sprouts are consumed as vegetables in Asian folk. In this study, the nutritional evaluation and antioxidant activity of sesame sprouts were investigated. As seeding days progressed, the free amino acids, γ-aminobutyric acid and total phenolic compounds in the sprouts were rapidly increased while sesamin was reduced. Although a fatty acid composition analysis showed that sesame sprouts were abundant in unsaturated fatty acids, the crude fat content was gradually reduced during sprout growth. In the antioxidant assays, it was found that the DPPH radical scavenging activity and the reducing power of the sprouts increased as the seeding days progressed, which was positively related to the total phenolic content. Sesame sprouts can be recommended for functional ingredients, as well as being an excellent dietary source of natural antioxidants.

Delineating the protein changes in Asian noodles induced by vacuum mixing.

In this study, the effect of vacuum mixing on Asian noodle qualities was investigated based on protein components changes and gluten formation. The results showed that the proportion of salt-soluble proteins decreased in vacuum mixed noodles while alcohol and alkali soluble proteins increased. The free sulfyhydryl content decreased significantly (P<0.05) in low protein (LP) noodles while slight and not significant (P>0.05) decrease was detected in high protein (HP) samples. Remarkable protein aggregates were observed in non-reduced SDS-PAGE patterns for LP noodles. The changes in secondary structure were reflected by the increase in α-helix and β-sheet as well as the decrease in β-turns. Furthermore, vacuum mixing conferred a more continuous and compact microstructure to both HP and LP noodle sheets as well as an increased breaking force and extensibility. In addition, less deterioration in noodle structure and water migration was observed by magnetic resonance imaging (MRI) for vacuum mixed samples during storage.

Isolation And Identification Of An Antioxidant Peptide Prepared From Fermented Peanut Meal Using Bacillus Subtilis Fermentation

In order to recover and utilize peanut protein resource, peanut meal was fermented using Bacillus subtilis to prepare antioxidant peptides in this study. The antioxidant activities of the peanut peptides were evaluated via six in vitro tests, namely, 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) scavenging activity, inhibition of linoleic acid autoxidation, reducing power, and metal chelating capacity. The peanut peptides showed 63.28% of scavenging effect on 1,1-diphenyl-2-picrylhydrazyl radical, 70.67% of scavenging effect on 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) and 39.32% of superoxide anion radical scavenging activity at 1.0 mg/ml, and 62.69% of inhibition on linoleic acid autooxidation at 0.8 mg/ml. Besides, the peanut peptides exhibited 32.8% of reducing power and 60.44% of Fe2+-chelating capacity at 2 mg/ml. Then the peanut peptides were desalted with macroporous resin; the fraction eluted with 75% ethanol showed the highest scavenging activity on 1,1-diphenyl-2-picrylhydrazyl radical. This fraction was subject to further purification using gel filtration chromatography and reverse phase-high performance liquid chromatography. At last, a peptide was gained, and it was identified to be Tyr-Pro with matrix-assisted laser desorption/ionization time-of-flight/time-of-flight mass spectrometry. The results indicated that it is feasible to prepare natural antioxidants from peanut meal using B. subtilis fermentation.

Improvement of emulsifying properties of oat protein isolate-dextran conjugates by glycation.

In order to improve the emulsifying properties of oat protein, oat protein isolate (OPI)-dextran (Dex) conjugates were prepared by glycation reaction. Emulsifying properties of emulsions stabilized by native OPI (OPIN), OPI-Dex conjugates (ODC) and heated OPI (OPIH) were characterized by zeta-potential, mean droplet size and microstructure. The results showed that the covalent attachment of OPI and dextran was confirmed by determining degree of graft and SDS-PAGE. OPI-Dex conjugates were capable of forming a finer emulsion, which exhibited smaller average particle size and better storage stability under different homogenization pressures (30, 60, 90 MPa) compared with OPIN and OPIH. When assessed in different pH and ionic strength, emulsions stabilized by OPI-Dex conjugates resulted in improved emulsion stability to environmental stresses. Confocal laser scanning microscopy depicted more uniform and smaller oil droplets that had a reduced tendency to coalesce for emulsions prepared with ODC.

Functional properties of chitosan–xylose Maillard reaction products and their application to semi-dried noodle

The objective of this research was to evaluate the antimicrobial, antioxidant and darkening inhibitory activities of Maillard reaction products (MRPs) prepared from chitosan and xylose, and their effects on the preservation and quality of semi-dried noodles. The development of brown color and UV absorbance changes indicated the proceeding of Maillard reaction. The antimicrobial activity, reducing power, DPPH radical scavenging activity, copper-chelating activity and PPO inhibitory effects of chitosan-xylose conjugates increased with the reaction. Addition of MRPs could improve the textural and cooking quality of semi-dried noodles. Incorporation of 0.35% MRPs (6 h) into semi-dried noodle resulted in an extension of shelf life for more than 7 days than the control noodles (at room temperature). The discoloration caused by the addition of MRPs was limited, and MRPs could inhibit darkening of the noodle effectively. Results suggested that the MRPs could be used as a novel promising preservative for semi-dried noodles.

Heat-induced interaction between egg white protein and wheat gluten

Some wheat-based food systems, such as cakes and cookies, include mixtures of gluten and egg white protein (EWP) and are processed under heating conditions. Changes in these proteins during processing can affect the quality of the end product. This study investigated protein polymerization during heating of (mixtures of) wheat gluten and EWP. Chemical changes were studied by size-exclusion high performance liquid chromatography (SE-HPLC), sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), thiol (SH) measurement and Fourier transform infrared (FTIR). During heating, protein polymerization was observed in the mixtures of gluten, glutenin, gliadin and EWP according to SE-HPLC profiles and results of SDS-extractable protein. The results of SDS-PAGE profiles of different proteins were in accordance with SE-HPLC. The number of SH groups in the majority of proteins showed a significant decrease, implying that disulfide (SS) bonds contributed to the extractability loss. In addition, changes of secondary structure tested by FTIR indicated protein aggregation.