Xiang Hong Li

Preliminary Purification and Distribution of Lipoxygenase in Grass Carp

The lipoxygenase (LOX) in grass carp can catalyze the oxidation of polyunsaturated fatty acids even their esters, resulting in rancidity deterioration of grass carp and its products during the process and storage. Preliminary purification, quantitative determination and distribution of grass carp muscular LOX were investigated in the present study. LOX activity of the grass carp muscle was measured to be 35.17 KU/g and its molecular weight was 95.71 kDa identified by SDS-PAGE. Using previously reported extraction methods such as twice salting-out and once dialysis, the LOX protein content in the crude muscular LOX extraction is about 28%. When salted with graded saturation of ammonium sulfate, we found once salting-out was enough for LOX extraction and the effective percentage saturation of ammonium sulfate for LOX extraction was 40%. Under this condition, the LOX protein content in the crude muscular LOX extract was doubled. The LOX distribution in fish was gradually increased from skin and muscle, gill, viscera to blood, which indicates that it is very important to remove the viscera and bleed fish completely during fish product processing to decrease the risk of lipid oxidation caused by LOX.

Effect of Germination on the Bio-Functional Components in the Germ-Remaining Polished Rice

The effects of germination on the bio-functional components in the germ-remaining polished rice have been investigated. The bio-functional components in the raw GRPR, brown rice and germinated brown rice were also characterized as the comparison. The results showed that a decrease in amylose content and an increase in reducing sugar were observed after germination. The germinated GRPR contains much more bio-functional components (GABA and dietary fiber) than GRPR and brown rice, and slightly less than germinated brown rice. The results also demonstrated that germinated GRPR contained less phytic acid than other three kinds of rice. Consequently, the nutritional value of GRPR had been improved by germination. Germination of GRPR would be a promising processing method to enhance the germinated rice consumption.

Comparison and Analysis of Acid-Stable and Acid-Unstable α-Amylases from Aspergillus niger with Computer

Aspergillus niger can produce an acid-stable α-amylase as well as an acid-unstable one, the relation between the structural differences and their acid-resistant capability is of great interest. In this paper, the primary parameters, secondary and tertiary structures of these two types of α-amylases was analyzed and compared, the results shows that they has 67% sequence identity and high homology in secondary and tertiary structure. The acid-stable α-amylase has lower isoelectric point and higher molar percent of acidic amino acid than the acid-unstable one. The four major structural differences of these two types of enzymes is located at residues 132-138, 206-212, 329-335 and 378-382 and formed vary fold pattern.

Effect of Germination on Physicochemical, Morphological and Rheological Properties of Rice Starch from Germ-Remaining Polished Rice

The effects of germination on physicochemical, morphological and rheological properties of rice starch from germ-remaining polished rice (GRPR) have been investigated. The properties of starches from raw GRPR, brown rice and germinated brown rice were also characterized as the comparison. The results showed that a decrease in amylose content was observed after germination and the amylose content of germinated GRPR was lower than that of germinated brown rice. Scanning electron microscopy did not reveal any distinct difference in the appearance of the starches except some slight alteration of the starch granule edges. Rheological investigation illustrated that the starches of GPRG with lower amylose content showed lower peak G’ in the four rice samples.

Research Hotspots in Trehalose Synthase Gene Engineering

This paper summarized and compared the characteristics of trehalose synthase (TS) from various bacteria and the research progress on TS gene engineering. The results show that analysis of TS structure and molecular modification are the research hotspots in TS gene engineering.

Rheological Properties of Rice Protein-Dextran Composite System

Rheological properties of rice protein-dextran composite system were studied. The formation of gel network-like structure appeared to have occurred through the interaction of rice protein and dextran at certain biopolymer concentration. An increase in the protein and/or polysaccharide concentration of the mixtures would contribute to the mechanical properties of mixed gels. The differences in fracture forces among samples as noticed in experiments also suggested the difference in microstructures.

Microencapsulation of GuaLou Seed Oil by Spray Drying

The objective of this work was to study the influence of some process conditions on the microencapsulation of Gualou seed oil by spray drying. The results showed that the best parameters of microencapsulation were as follows: the ratio of arabic gum to maltodextrin was 1:1, and that of core material to wall material was 2:3; and the total solids content was 25%. The optimum spray drying conditions were that the air temperature of inlet was 180 °C, and that of outlet was 80 °C; the homogenizing pressure was 35MPa. The maximum microencapsulation efficiency was 86±0.95%.

Changes in Muscle Protein Fractions of Grass Carp (Ctenopharyngodon idellus) during Early Storage Period

Muscle proteins degradation is one of the important manifestations relating to corruption of freshwater fishes during storage. In this paper, the changes in molecular weight distribution of grass carp muscle proteins during storage at nomal temperature were analyzed by SDS-PAGE and SEC-HPLC measurements. The results showed that the fish muscle proteins were always subject to changes during the whole process of storage, but significant changes of fish muscle proteins took place after 24 hours of storage. Particularly, the high molecular weight proteins were almost completely degraded after storage 24 hours, and the low molecular weight proteins were relatively stable but still undertaken more than 50% of degradation. Our results provide some new evidence for the change law of fish muscle proteins during early storage period.

Combination of Chlorogenic Acid and Bamboo Charcoal Particles Improve Husbandry Performance and Environment

The objective of this study was to determine the effects of chlorogenic acid (CA) and bamboo charcoal particles activated by microwave (BCP) on performance, serum urea nitrogen and husbandry environment of broilers. The diets were devoid of antibiotic growth promoters (AGP). Two hundred and forty Avian broilers were allocated to a 2 × 2 factorial experiment involving two levels of CA (0 or 1000 mg CA/kg feed), and two levels of BCP supplementation (0 or 100 mg/kg feed). The diets and water were offered ad libitum. The growth performance and serum urea nitrogen was significantly increased when CA supplemented (P<0.05), while BCP significantly affects the ammonia concentration of the husbandry environment (P<0.05). These results indicate that CA and BCP combination can effectively improve the performance and husbandry environment.