Methylobacterium nigriterrae sp. nov., isolated from black soil.

An aerobic, Gram-stain-negative, motile rod bacterium, designated as SYSU BS000021T, was isolated from a black soil sample in Harbin, Heilongjiang province, China. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the isolate belongs to the genus Methylobacterium, and showed the highest sequence similarity to Methylobacterium segetis KCTC 62267 T (98.51%) and Methylobacterium oxalidis DSM 24028 T (97.79%). Growth occurred at 20-37℃ (optimum, 28 °C), pH 6.0-8.0 (optimum, pH 7.0) and in the presence of 0% (w/v) NaCl. Polar lipids comprised of phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, one unidentified aminolipid and one unidentified polar lipid. The major cellular fatty acids (> 5%) were C18:0 and C18:1 ω7c and/or C18:1 ω6c. The predominant respiratory quinone was Q-10. The genomic G + C content was 68.36% based on the whole genome analysis. The average nucleotide identity (≤ 83.5%) and digital DNA-DNA hybridization (≤ 27.3%) values between strain SYSU BS000021T and other members of the genus Methylobacterium were all lower than the threshold values recommended for distinguishing novel prokaryotic species. Based on the results of phenotypic, chemotaxonomic and phylogenetic analyses, strain SYSU BS000021T represents a novel species of the genus Methylobacterium, for which the name Methylobacterium nigriterrae sp. nov. is proposed. The type strain of the proposed novel species is SYSU BS000021T (= GDMCC 1.3814 T = KCTC 8051 T).

Oregano essential oil encapsulated in zein-pectin-chitosan nanoparticles to improve the storage quality of Harbin red sausage.

In this study, the effect of oregano essential oil loaded in zein-pectin-chitosan (Zein-PC-CS-OEO) nanoparticles on the quality of Harbin red sausage during storage was examined. Zein-PC-CS-OEO nanoparticles exhibit the better encapsulation efficiency, antioxidant and antibacterial properties than these of other prepared nanoparticles, which were subsequently incorporated into Harbin red sausage with different concentrations. The physicochemical properties, bacterial community structure, and flavor characteristics of the Harbin red sausage were determined. Both thiobarbituric acid values and the growth of dominant spoilage bacteria in Harbin red sausage are inhibited by Zein-PC-CS-OEO nanoparticles, while the total aerobic bacteria count is reduced. These results indicate that the storage quality of Harbin red sausage is improved by Zein-PC-CS-OEO nanoparticles. It is worth noting that the shelf life of Harbin red sausage supplemented with 0.1 % Zein-PC-CS-OEO nanoparticles is extended to 9 d, and the flavor characteristics of which are better maintained. This study provides a new approach to extend the application of essential oil and improve the storage quality of Harbin red sausage.

Influences of Smoking in Traditional and Industrial Conditions on Flavour Profile of Harbin Red Sausages by Comprehensive Two-Dimensional Gas Chromatography Mass Spectrometry.

Smoking is mainly used to impart desirable flavour, colour and texture to the products. Various food smoking methods can be divided into traditional and industrial methods. The influences of three different smoking methods, including traditional smouldering smoke (TSS), industrial smouldering smoke (ISS) and industrial liquid smoke (ILS), on quality characteristics, sensory attributes and flavour profiles of Harbin red sausages were studied. The smoking methods had significant effects on the moisture content (55.74-61.72 g/100 g), L*-value (53.85-57.61), a*-value (11.97-13.15), b*-value (12.19-12.92), hardness (24.25-29.17 N) and chewiness (13.42-17.32). A total of 86 volatile compounds were identified by headspace solid phase microextraction combined with comprehensive two-dimensional gas chromatography mass spectrometry (GC × GC-qMS). Among them, phenolic compounds were the most abundant compounds in the all sausages. Compared with sausages smoked with smouldering smoke, the ILS sausages showed the highest content of volatile compounds, especially phenols, alcohols, aldehydes and ketones. Principal component analysis showed that the sausages smoked with different methods had a good separation based on the quality characteristics and GC × GC-qMS data. These results will facilitate optimising the smoking methods in the industrial production of smoked meat products.

Ultrasonic-assisted extraction of polyphenol from the seeds of Allium senescens L. and its antioxidative role in Harbin dry sausage.

The ultrasonic-assisted extraction of total polyphenol from Allium senescens L. (ASL) seeds was conducted, and the antioxidant efficacy of ASL seed extract (ASLSE) was assessed in Harbin dry sausages. ASLSE extracted with 1:30 g/mL water at 150 W for 15 min had the highest antioxidant capacities (P < 0.05). Subsequently, different addition levels (0, 2, 4, 6 and 8 g/kg) of freeze-dried ASLSE were applied in dry sausages during a twelve-day fermentation, and BHT treatment was the positive control. The lower pH values and carbonyl contents were detected in the treatments with 6 and 8 g/kg ASLSE than those in the other treatments at 12 d (P < 0.05). However, there was no difference in the water activity, lipid oxidation and color among the treatments with 6 and 8 g/kg ASLSE and 0.2 g/kg BHT (P > 0.05) at 12 d. These results indicated that 6 g/kg ASLSE could be effective in inhibiting lipid and protein oxidation and reducing color deterioration of dry sausages.

Effects of partial replacement of pork back fat by a camellia oil gel on certain quality characteristics of a cooked style Harbin sausage.

Various portions of pork fat in Harbin sausage were replaced by a camellia oil gelled emulsion during the process, and the subsequent effects were studied in order to improve their quality characteristics and fatty acid composition. Percentages of pork back fat replacement were 10%, 20%, 30%, 40% and 50%. Proximate composition, instrumental color and texture, pH, TBARS and fatty acid composition of the sausages were studied after substituting portion of the pork fat with camellia oil gelled emulsion. The replacement of pork back fat by camellia oil gels did not affect the cohesiveness, resilience, springiness and protein content, while it increased moisture content, lightness and yellowness. TBARS values was significantly (P < 0.05) decreased by the pork back fat substitution. Addition of camellia oil gels significantly (P < 0.05) affected the fatty acid profile. The study suggests that a substantial reduction in SFA can be achieved by incorporating camellia oil gels in Harbin sausage without clearly affecting the studied sausage properties.