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Cheng X.,Nanjing Agricultural University | He W.,Nanjing Agricultural University | Huang F.,Key Laboratory of Agro products Processing | Huang M.,Nanjing Agricultural University | Zhou G.,Nanjing Agricultural University
Food Research International | Year: 2014

Food authentication and quality control requires sensitive species-specific identification and quantification of DNA from unknown sources. An accurate and reliable multiplex TaqMan® real-time quantitative PCR (qPCR) method modified from Köppel et al. (2009) based on the specific sites of nuclear DNA has been developed to identify duck, pig and chicken DNA in blood curds. Total DNA in blood curd samples was extracted using three methods: TIANamp® Blood DNA Kit, TIANamp® Genomic DNA Kit and a modified phenol/chloroform extraction method. The concentration and purity of DNA were compared regarding DNA yields and purity. A modified phenol/chloroform extraction method and the TIANamp® Genomic DNA Kit gave improved extraction efficiencies compared with the TIANamp® Blood DNA Kit. The limit of detection (LOD) of the assay was 0.15ng for each target species (1:103 dilution). Analysis of experimental mixtures demonstrated that the sensitivity of the assay was 1% for each species analyzed. This system proved its accuracy, precision and applicability for the examination of different types of animal blood in blood curd products of the type presently on the market. © 2014. Source

Zhong K.,Key Laboratory of Agro products Processing | Zhang Q.,Key Laboratory of Agro products Processing | Tong L.,Key Laboratory of Agro products Processing | Liu L.,Key Laboratory of Agro products Processing | And 2 more authors.
Ultrasonics Sonochemistry | Year: 2014

Molecular weight degradation effects of schizophyllan (SPG) under ultrasonic treatments were investigated in this study. The degradation product was treated by alcohol fractional precipitation technology, and the molecular weight and rheological properties of ultrasonic-treated SPG (USPG) fractions were evaluated. Average molecular weight of SPG decreased significantly after ultrasonic treatments, and degradation product had more narrow distribution of molecular weight. The molecular weight degradation kinetics of SPG is adequately described by a second-order reaction. USPG fractions with different molecular weight were obtained by fractional precipitation for final alcohol concentration fractions 0-40%, 40-60% and 60-80%, respectively. USPG fractions had near-Newtonian flow behaviors, and USPG80% exhibited viscous responses over the entire accessible frequency range. Therefore, ultrasonic treatment is a viable modification technology for SPG and other polymer materials with high molecular weight. © 2014 Elsevier B.V. All rights reserved. Source

Zhang M.,Chinese Academy of Agricultural Sciences | Zhang M.,Key Laboratory of Agro products Processing | Mu T.-H.,Chinese Academy of Agricultural Sciences | Mu T.-H.,Key Laboratory of Agro products Processing | And 2 more authors.
Journal of Functional Foods | Year: 2014

Sweet potato protein hydrolysates (SPPH) were prepared by Alcalase. The OH scavenging activity and Fe2+-chelating ability of SPPH were investigated. SPPH was further separated into four fractions by membrane ultrafiltration, and low-molecular-weight fraction F-IV (<3kDa) exhibited the strongest OH scavenging activity and Fe2+-chelating ability, which was 59.74% and 82.27% at a concentration of 3.0mg/mL, respectively. Fraction F-IV was then purified with size exclusion chromatography (SEC) followed by RP-HPLC, by which two fractions IV-5c and IV-5i with the highest antioxidant activities were obtained. Five peptides derived from fractions IV-5c and IV-5i were characterized by LC-MS/MS, of which Thr-Tyr-Gln-Thr-Phe, Ser-Gly-Gln-Tyr-Phe-Leu and Tyr-Met-Val-Ser-Ala-Ile-Trp-Gly matched the sequence of sporamin A, while Tyr-Tyr-Ile-Val-Ser and Tyr-Tyr-Asp-Pro-Leu matched the sequence of sporamin B. In addition, OH scavenging activities of the five peptides were determined using synthesized peptides, and Tyr-Tyr-Ile-Val-Ser showed the highest OH scavenging activity, which was 74.52% at a concentration of 1.0mg/mL. © 2014 Elsevier Ltd. Source

Wang Y.,Chinese Academy of Agricultural Sciences | Wang Y.,Key Laboratory of Agro products Processing | Wang L.,Chinese Academy of Agricultural Sciences | Liu F.,Chinese Academy of Agricultural Sciences | And 8 more authors.
Toxins | Year: 2016

Ochratoxin A (OTA), mainly produced by Aspergillus and Penicillum species, is one of the most important mycotoxin contaminants in agricultural products. It is detrimental to human health because of its nephrotoxicity, hepatotoxicity, carcinogenicity, teratogenicity, and immunosuppression. OTA structurally consists of adihydrocoumarin moiety linked with L-phenylalanine via an amide bond. OTA biosynthesis has been putatively hypothesized, although several contradictions exist on some processes of the biosynthetic pathway. We discuss recent information on molecular studies of OTA biosynthesis despite insufficient genetic background in detail. Accordingly, genetic regulation has also been explored with regard to the interaction between the regulators and the environmental factors. In this review, we focus on three aspects of OTA: OTA-producing strains, OTA biosynthetic pathway and the regulation mechanisms of OTA production. This can pave the way to assist in protecting food and feed from OTA contamination by understanding OTA biosynthetic pathway and regulatory mechanisms. © 2016 by the authors; licensee MDPI, Basel, Switzerland. Source

Wang L.,Chinese Academy of Agricultural Sciences | Wang Y.,Chinese Academy of Agricultural Sciences | Wang Y.,Key Laboratory of Agro products Processing | Wang Q.,Chinese Academy of Agricultural Sciences | And 11 more authors.
Toxins | Year: 2015

Ochratoxin A (OTA), a potentially carcinogenic mycotoxin which contaminates grains, is produced by several Aspergillus species. A comparative sequence analysis of the OTA-producing Aspergillus ochraceus fc-1 strain and other Aspergillus species was performed. Two new OTA-related polyketide synthase (PKS) (AoOTApks) genes were identified. The predicted amino acid sequence of AoOTApks-1 displayed high similarity to previously identified PKSs from OTA-producing A. carbonarius ITEM 5010 (67%; [PI] No. 173482) and A. niger CBS 513.88 (62%; XP_001397313). However, the predicted amino acid sequence of AoOTApks-2 displayed lower homology with A. niger CBS 513.88 (38%) and A. carbonarius ITEM 5010 (28%). A phylogenetic analysis of the β-ketosynthase and acyl-transferase domains of the AoOTApks proteins indicated that they shared a common origin with other OTA-producing species, such as A. carbonarius, A. niger, and A. westerdijkiae. A real-time reverse-transcription PCR analysis showed that the expression of AoOTApks-1 and -2 was positively correlated with the OTA concentration. The pks gene deleted mutants ΔAoOTApks-1 and ΔAoOTApks-2 produced nil and lesser OTA than the wild-type strain, respectively. Our study suggests that AoOTApks-1 could be involved in OTA biosynthesis, while AoOTApks-2 might be indirectly involved in OTA production. © 2015 by the authors; licensee MDPI, Basel, Switzerland. Source

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