Tianjin Agricultural University

About: Tianjin Agricultural University is a education organization based out in Tianjin, China. It is known for research contribution in the topics: Gene & Population. The organization has 2107 authors who have published 1496 publications receiving 11815 citations.

Cloning and characterization of a novel β-carotene hydroxylase gene from Lycium barbarum and its expression in Escherichia coli.

Abstract: Lycium barbarum contains high levels of zeaxanthin, which is produced by the conversion of β-carotene into zeaxanthin. β-Carotene hydroxylase catalyzes this reaction. We cloned a cDNA (chyb) encoding β-carotene hydroxylase (Chyb) from the L. barbarum leaf. A 939-bp full-length cDNA sequence was determined with 3'-rapid amplification of cDNA end assay encoding a deduced Chyb protein (34.8 kDa) with a theoretical isoelectric point of 8.36. A bioinformatics analysis showed that the L. barbarum Chyb was located in the chloroplast. Further, to investigate the catalytic activity of the L. barbarum Chyb, a complementation analysis was conducted in Escherichia coli. The results strongly demonstrated that Chyb can catalyze β-carotene to produce zeaxanthin. Thus, this study suggests that L. barbarum β-carotene hydroxylase could be a means of zeaxanthin production by genetic manipulation in E. coli.

The Application of a Compound Natural Preservative Solution to Chilled Beef and Mutton Under Vacuum Packaging During Refrigerated Storage

Abstract: A compound natural preservative (CNP) was produced by mixing clove cinnamon extracts with tea polyphenol, chitosan, propolis, nisin and lysozyme. Its effects on microbiological [total aerobic counts (TACs)], chemical [total volatile base nitrogen (TVB-N), 2-thiobarbituric reactive substances (TBARS), total reducing activity (TRA) and pH values], and colorimetric characteristics of chilled beef and mutton that were kept under vacuum packaging during refrigerated storage at 4 ± 1°C were investigated for 4 weeks. Results indicated that the CNP significantly inhibited the growth of microbes, improved TRA values, and decreased TBARS and TVB-N values to some extent especially at the later storage time, but had no obvious advantage in maintaining the color stability of beef and mutton when compared to lactic acid (LA, positive control) and sterile distilled water (DW, negative control). The shelf-lives of chilled beef and mutton were observed to be 3 − 4 weeks for the CNP treatment. The susceptibility of meat species to lipid oxidation was greater in beef than mutton, but spoilage as a consequence of bacteria load was greater in mutton than beef.