保加利亚乳杆菌生长性能与后酸化的关系初探

以5株德氏乳杆菌保加利亚亚种为出发菌株,详细研究了5株菌的生长代谢、酸敏感性及蛋白水解力,并分析了这些特性与后酸化之间的关系。结果表明:5株菌的生长性能与后酸化之间存在紧密联系。其中,菌株的生长速度和糖分解代谢能力与后酸化成正比;对酸较敏感菌株的后酸化也较弱;菌株的蛋白水解能力与生长速度和后酸化之间没有明显的相关性。     

Proteomic analysis of differentially expressed whey proteins in Saanen goat milk from different provinces in China using a data-independent acquisition technique

Whey proteins of Saanen goat milk samples from 3 provinces in China (Guangdong, GD; Inner Mongolia, IM; Shaanxi, SX) were characterized and compared using data-independent acquisition quantitative proteomics technique. A total of 550 proteins were quantified in all 3 samples. There were 44, 44, and 33 differentially expressed proteins (DEP) for GD versus IM, GD versus SX, and IM versus SX, respectively. Gene ontology annotation analysis showed that the largest number of DEP for the 3 comparisons were as follows: for biological processes: response to progesterone, glyceraldehyde-3-phosphate metabolic process, and negative regulation of megakaryocyte differentiation; for molecular functions: antioxidant activity, binding, and peroxiredoxin activity; and for cellular components: the same category of extracellular regions for the 3 comparisons, respectively. Pathways for the DEP of 3 comparisons were (1) disease; (2) synthesis and metabolism; and (3) synthesis, degradation, and metabolism. Protein–protein interaction network analysis showed that DEP for GD versus SX had the most interactions.     

In vitro antioxidant and anti-inflammation properties of lactic acid bacteria isolated from fish intestines and fermented fish from the Sanriku Satoumi region in Japan

The Ministry of the Environment, Government of Japan, defines a Satoumi as a coastal area where biological productivity and biodiversity has increased through human interaction. As a way to identify new starters and probiotics, we isolated and screened lactic acid bacteria (LAB) with acid, bile, and salt resistance from the intestines of 23 fish and 11 fermented fish samples obtained from the northeastern (Sanriku) Satoumi region of Japan. Of the 301 isolates, 75 strains were selected as LAB, 6 of which clearly showed increased antioxidant activities (DPPH and O₂⁻ radical scavenging and Fe-reducing power) in their cultured broth. Four isolates (S-SU1, 3–5) were identified as Lactobacillus plantarum. The two other strains (S-SU2, 6) identified were Lactococcus lactis and Pediococcus pentosaceus. In these in vitro assays, Lc. lactis S-SU2, isolated from sea pineapple kimchi showed the highest radical scavenging capacity. Moreover, the protective effect of heat-killed cells against the toxicity of 3 mM H₂O₂ on Saccharomyces cerevisiae was the highest for Lb. plantarum S-SU1 isolated from a salted squid product, followed by P. pentosaceus S-SU6 isolated from the intestines of blue mackerel. Furthermore, Lb. plantarum S-SU5 showed inhibitory effect against the toxicity of 3 mM H₂O₂ in human enterocyte-like HT-29-luc cells and on nitrite (NO) production in mouse RAW264.7 macrophage cells, which was induced by Escherichia coli O111 lipopolysaccharide (LPS). These results suggest that the selected LAB strains are potential starters and/or functional components with antioxidant and anti-inflammatory properties.     

Controlled whey protein aggregates to modulate the texture of fat-free set-type yoghurts

The impact of nanoparticulated whey protein aggregates on the texture of fat-free set-type yoghurts was investigated. Monodisperse (MFA) and polydisperse (PFA) fractal aggregates obtained from heated whey protein isolate (WPI) were added to skimmed milk for yoghurt manufacture at four different concentrations (0.2%–1.5%, w/w). The impact of the concentration and the polydispersity of the aggregates on fat-free set-type yoghurts were studied by instrumental measurements (rheology, penetrometry, syneresis and microscopy) and sensory analysis. Yoghurt gel strength and firmness increased with the concentration of WPI, MFA and PFA. However, yoghurts enriched with PFA clearly differed from the yoghurts enriched with WPI. Indeed, yoghurts enriched with PFA were characterised by a weak gel, a low firmness and a low-density of the protein network. Sensory analysis confirmed the results obtained by instrumental measurements. The whey protein aggregates studied are thus promising tools to modulate fat-free yoghurt texture while using milk-derived ingredients.     

基于GIS技术的工程地质环境系统构建及治理分析

针对传统的工程地质环境系统存在的收集图像与原始图像同向性较低的问题,以下开展了基于GIS技术的工程地质环境系统的构建研究。采用设计对比实验的方式验证该系统在实际应用过程中,可提升收集图像与原始图像的同向程度。     

Automatic monitoring system for individual dairy cows based on a deep learning framework that provides identification via body parts and estimation of body condition score

Body condition score (BCS) is a common tool for indirectly estimating the mobilization of energy reserves in the fat and muscle of cattle that meets the requirements of animal welfare and precision livestock farming for the effective monitoring of individual animals. However, previous studies on automatic BCS systems have used manual scoring for data collection, and traditional image extraction methods have limited model performance accuracy. In addition, the radio frequency identification device system commonly used in ranching has the disadvantages of misreadings and damage to bovine bodies. Therefore, the aim of this research was to develop and validate an automatic system for identifying individuals and assessing BCS using a deep learning framework. This work developed a linear regression model of BCS using ultrasound backfat thickness to determine BCS for training sets and tested a system based on convolutional neural networks with 3 channels, including depth, gray, and phase congruency, to analyze the back images of 686 cows. After we performed an analysis of image model performance, online verification was used to evaluate the accuracy and precision of the system. The results showed that the selected linear regression model had a high coefficient of determination value (0.976), and the correlation coefficient between manual BCS and ultrasonic BCS was 0.94. Although the overall accuracy of the BCS estimations was high (0.45, 0.77, and 0.98 within 0, 0.25, and 0.5 unit, respectively), the validation for actual BCS ranging from 3.25 to 3.5 was weak (the F1 scores were only 0.6 and 0.57, respectively, within the 0.25-unit range). Overall, individual identification and BCS assessment performed well in the online measurement, with accuracies of 0.937 and 0.409, respectively. A system for individual identification and BCS assessment was developed, and a convolutional neural network using depth, gray, and phase congruency channels to interpret image features exhibited advantages for monitoring thin cows.     

Milk fat globule size,phospholipid contents and composition of milk from purebred and Alpine-crossbred Mid-Eastern goats under confinement or grazing condition

Milk fat globule (MFG) size and phospholipids (PL) content and composition were determined in milk collected at 65 (pretreatment), 110, 135 and 170 days of lactation from goats randomly assigned to grazing in Mediterranean brushland or fed clover hay indoors, in addition to concentrate. Daily feed intake and dietary contents of neutral detergent fibre and acid detergent fibre were higher in grazing goats, associated with milk richer in fat, with larger MFGs and 20% higher PL content. Smaller MFGs, produced by all confinement groups, was associated with 15 μg g⁻¹ fat higher milk PL content. The greatest effect was found in the Damascus goats, with over 44% higher PL concentration, on milk fat basis, in the confined compared with grazing group. Our understanding of how PL content is modulated by the interaction between genetic background and nutrition will enable to achieve either PL-rich milk or PL-enriched milk fat.     

The nutrient requirements of Lactobacillus rhamnosus GG and their application to fermented milk

Lactobacillus rhamnosus GG (LGG) performs many physiological functions, but the fermentation time is long when fermented milk is prepared using LGG alone. To shorten the fermentation time, we analyzed the nutrient requirement profiles of LGG. Based on nutrient requirement profiles, we evaluated the effects on the fermentation time, quality, and sensory properties of unmodified cow's milk fermented by LGG alone. According to the consumption and necessary patterns of amino acids and those of purine, pyrimidine, vitamins, metal ions, and nutrients essential to LGG, we selected Cys, Ser, Arg, Pro, Asp, Glu, guanine, uracil, and xanthine with which to supplement milk. Compared with fermented milk prepared using LGG alone in unmodified milk, the fermentation time of supplemented milk was shortened by 5 h. Viable cell counts, titratable acidity, and water-retaining capability of the fermented milk were improved by addition of nutrient supplements. Supplementation with nutrients did not obviously change the sensory and textural characteristics of fermented milk.     

Effective thermal conductivity of thermokarst lake ice in Beiluhe Basin,Qinghai-Tibet Plateau

Effective thermal conductivity (ETC) of thermokarst lake ice (TLI) is a key factor in simulating the ice processes in permafrost regions of Qinghai-Tibet Plateau (QTP). Typical TLI blocks sampled from central QTP were prepared to measure their ETC in vertical and horizontal directions at various temperatures. The ETC values of TLI are ranging between 1.60 and 2.10 W/(mK). The ETC values in both directions are very close, and change obviously along the ice depth. The ETC of TLI increases monotonously with decreasing ice temperature between 0 and 25 °C. Both the theoretical modeling and experimental results demonstrate the effects of gas pore structures on ETC of TLI. The temperature-averaged ETC decreases gradually as the porosity increases. A simple linear combination of two structural models is proposed for predicting the ETC against the porosity by introducing an empirical coefficient. This coefficient is controlled by the gas pore size, content, shape and configuration.     

Comparative study of proximate composition and amino acid in farmed and wild Pseudobagrus ussuriensis muscles

The proximate composition and amino acid compositions of the muscle of wild and farmed Pseudobagrus ussuriensis were compared. The lipid content of the farmed fish was significantly higher, while moisture content was significantly lower, than those of the wild fish. Pseudobagrus ussuriensis protein has a well‐balanced amino acid composition. The percentages of total amino acids, essential amino acids, nonessential amino acids and delicious amino acids were significantly higher in the wild than those in farmed fish. The ratios of W_EAA to W_TAA (42.78%–43.02%) and W_EAA to W_NEAA (85.52%–87.74%) were comparable to the reference values of 40% and above 60% recommended by FAO/WHO. According to the amino acid scores, methionine would have been described as the first limiting amino acid, and Lys had the highest score for the protein in both wild and farmed Pseudobagrus ussuriensis. This study shows that Pseudobagrus ussuriensis under investigation have high nutritional qualities and are good protein resources.