Predicting distribution of Zanthoxylum bungeanum Maxim. in China.

BACKGROUND: With the growth of economic benefits brought by Zanthoxylum bungeanum Maxim. and the increasing market demand, this species has been widely introduced and cultivated in China. It is important to scientifically select suitable areas for artificial planting and promotion, and to understand the status and potential of Z. bungeanum resources. RESULTS: The maximum entropy (MaxEnt) model and ArcGIS technologies were used to analyze the climatic suitability of Z. bungeanum based on known distribution data, combined with environmental data in China. Z. bungeanum was mainly distributed in subtropical and mid-eastern warm temperate regions. The total suitable area (high and medium suitability) accounted for 32% of China's total land area, with high suitability areas composing larger percentage, reaching 1.93 × 106 km2. The suitable range (and optimum value) of the key environmental variables affecting the distribution of Z. bungeanum were the maximum temperature in February of 2.8-17.7 °C (10.4 °C), the maximum temperature in March of 8.6-21.4 °C (16.3 °C), the maximum temperature in December of 2.5-17.1 °C (9.9 °C), the maximum temperature in November of 7.7-22.2 °C (14.5 °C) and the mean temperature in March of 3.2-16.2 °C (12.0 °C). CONCLUSIONS: The model developed by MaxEnt was applicable to explore the environmental suitability of Z. bungeanum.

Extraction, purification and antioxidant activity of polysaccharide from cold pressed oil cake of 'Tengjiao' seed.

Tengjiao (Zanthoxylum armatum DC.) seed cold pressed oil cake (CPC), the main by-product of the cold-pressed oil process, is mainly used for animal feed or crop fertilizer, resulting in a great waste of resources. To improve the added value, the CPC polysaccharide (CPCP) was extracted and purified, and its antioxidant activity was studied. The extraction conditions by microwave assisted extraction, and purification conditions by trichloroacetic acid and polyamide column chromatography treatment were optimized. High performance liquid chromatography and Fourier transforms infrared were applied to characterize the primary structural features. And the antioxidant activity was analyzed by detecting the reducing power, and scavenging activity on radical of superoxide anion, DPPH and ABTS. The results showed that, under the optimal extraction conditions (liquid-to-solid ratio 44 mL/g, processing time 16 min, microwave power 500 W and extraction temperature 80 °C), and the optimal purification conditions, the extract rate of crude CPCP reached 4.76 ± 0.07%, and the purity increased from 48.52 ± 2.76% to 93.76 ± 2.06%. CPCP was mainly water-soluble pyranose with α-configuration, and composed of five kinds of monosaccharides including L-Rhamnose, D-Glucuronic acid, d-Glucose, D-Galactose and D-(-)-Arabinose. CPCP displayed certain degree of antioxidant activity, revealing the potential development and utilization value as antioxidants.

Properties comparison between free and immobilized wheat esterase using glass fiber film.

In this paper, the catalytic performance of non-purified esterase from wheat bran immobilized on glass fibre membrane carrier is established, the immobilization conditions observed were enzyme 1 mL, phosphate buffer 3 mL (pH 7.0), immobilization time 1 h, immobilization temperature 29 °C. After carrier functionalization some characteristics of immobilized enzyme were studied, the results showed that immobilized enzyme presenting improved characteristic than that of free enzyme. The optimum pH for free and immobilized enzymes were found to be 8 and 7, respectively. As for optimum temperature for free and immobilized enzymes were observed to be 30 °C and 40 °C, respectively. When the enzyme was immobilized on glass fibre membranes, its Km increased about 7 times. In addition, storage and thermal stability of the free wheat esterase were increased by as a result of membrane immobilization, after 12 days of storage, the immobilized enzyme still retained about 91.10% of its original activity at 4 °C, indicating a great potential in industrial application.

Use of Psychrotolerant Lactic Acid Bacteria (Lactobacillus spp. and Leuconostoc spp.) Isolated from Chinese Traditional Paocai for the Quality Improvement of Paocai Products.

To improve the quality of Chinese traditional Paocai, two psychrotolerant lactic acid bacteria (LAB) strains were isolated from Paocai, and the quality of Chinese Paocai product using these two strains as starter cultures was compared to a control sample fermented with aged brine at 10 °C. The results suggested that the physicochemical and sensory features of Paocai fermented with psychrotolerant LAB were more suitable for industrial applications. The nitrite content of Paocai fermented with psychrotolerant LAB was 1 mg/kg, which was significantly lower than that of the control Paocai (P < 0.05). Low-temperature fermentation with the starter cultures of psychrotolerant LAB could effectively prevent overacidity and over-ripening of the Paocai products. Additionally, Paocai fermented with psychrotolerant LAB harbored relatively simple microbial flora as revealed by polymerase chain reaction-denaturing gradient gel electrophoresis. This study provides a basis for improving the quality of Chinese traditional Paocai and the large-scale production of low-temperature Chinese traditional Paocai products.

Antimicrobial Activities of Nisin, Tea Polyphenols, and Chitosan and their Combinations in Chilled Mutton.

Antimicrobial activities of nisin, tea polyphenols (TPs), and chitosan, and their combinations were evaluated against both Gram-positive bacteria (GPB) and Gram-negative bacteria (GNB) by the agar dilution method. Results showed that the MIC of nisin was 2.44 to 1250 mg/L for GPB and reached 5000 mg/L for GNB. The MICs of TPs and chitosan were 313 to 625 mg/L and 469 mg/L for GNB, and 156 to 5000 mg/L and 234 to 938 mg/L for GPB, respectively. These results indicated that TPs and chitosan exhibited inhibitory effects against both GPB and GNB, whereas nisin inhibited the growth of GPB only. Based on the orthogonal test of their MICs, and evaluation of preservative effect and sensory attributes in chilled mutton, the optimum combination was chosen as 0.625, 0.313, and 3.752 g/L for nisin, TPs, and chitosan, respectively. By using the optimum treatment, the shelf life of chilled mutton was extended from 6 to 18 d at 4 °C in the preservative film packages. These results indicate that the combination of nisin, TPs, and chitosan could be used as preservatives to efficiently inhibit the growth of spoilage microorganisms and pathogens in meat, thus improving the safety and shelf life of chilled mutton.

[Bacterial biodiversity in Dongcai, a traditional pickled mustard product in Sichuan Province, China].

OBJECTIVE: To investigate the bacteria community and biodiversity of four-years pickled Yanshan Dongcai. METHODS: We studied the bacterial communities of Dongcai by 16S rDNA diversity analysis and the cultured species isolated from Dongcai sample by Restriction Fragment Length Polymorphism (RFLP) and 16S rRNA gene sequence analysis. RESULTS: The 16S rDNA diversity showed that the bacteria belonged to the phyla Proteobacteria (87.9% ) and Firmicutes (7.1% ), including many moderately halophilic bacteria such as Virgibacillus kekensis, Marinococcus albus, Salinicoccus sp., Lactobacillus halophilus and Halomonas. Only 5% of clone sequences belonged to the phylum Actinobacteria. Thirty-five strains were isolated from Dongcai sample, and 16S rDNA-RFLP analysis indicated that 34 isolates affiliated with the phylum Firmicutes, including Virgibacillus, Bacillus megaterium and Gracilibacillus saliphilus which were moderately halophilic bacteria, but only one isolate belonged to the phylum Actinobacteria. CONCLUSION: The bacterial diversity is low in Dongcai, dominated by moderately halophilic bacteria.