Effects of high hydrostatic pressure on the structure and retrogradation inhibition of oat starch

As a non-thermal processing technology, high hydrostatic pressure (HHP) can be used for starch modification without affecting the quality and flavour constituents. The effect of HHP on starch is closely related to the treatment pressure of HHP. In this paper, we investigated the impacts of HHP treatment pressure (0, 100, 200, 300, 400, 500, 600 MPa) on the microstructure and retrogradation characteristics of oat starch, established the retrogradation kinetic model and elaborated the mechanism of HHP treatment inhibiting the retrogradation of oat starch. Results show that HHP treatment caused the microstructure of oat starch experienced crystallisation perfection (100–300 MPa), crystallisation destruction (400 MPa), crystallisation disintegration and gelatinisation (500–600 MPa). Results of oat starch retrogradation showed that, after treated at 500 MPa for 15 min, the recrystallisation rate of oat starch was reduced, the formation of nuclei at the early stage of oat starch retrogradation suppressed and its nucleation mode was changed from instantaneous to spontaneous, otherwise, the mobility of water in oat starch gel system reduced. Therefore, 500 MPa treated for 15 min can inhibits the retrogradation of oat starch. This study provides theoretical guidance for the application of HHP technology in starch modification and food processing.     

西藏燕麦主要种植区灌溉定额空间分布及影响因素

燕麦为西藏自治区典型牧草之一,由于种植区地域辽阔,灌溉试验结果受限,西藏燕麦主要种植区的灌溉定额尚不明确。本文在西藏燕麦主要种植区内选取28个典型站点进行资料收集,遵循农业气候相似原则进行区域划分,基于水量平衡法揭示了西藏燕麦主要种植区灌溉定额的空间分布特征,并根据统计学原理分析了其影响因素。研究表明:燕麦主要种植区的灌溉定额呈由西藏中部至东部呈现先递增后递减的趋势,50%水文年下的燕麦灌溉定额在56~265 mm之间变化。降雨量是影响研究区内燕麦灌溉定额的主要因素(R²为0.515),ET₀次之(R²为0.152);其它气象因素中,日照时数对研究区燕麦灌溉定额影响较大(R²为0.462),且呈正相关关系;相对湿度对燕麦灌溉定额影响较小。西藏燕麦主要种植区的灌溉定额及其空间分布可为西藏自治区灌溉用水管理提供支撑。     

Enterococcus faecium AS8及其胞外多糖对发酵乳流变学特性的影响

通过红外光谱、气相色谱-质谱联用和流变仪的检测,探究产自屎肠球菌(Enterococcus faecium)AS8的胞外多糖(exopolysaccharide,EPS)(AS8-EPS)的结构组成和流变性能。采用3种发酵乳作为样品,分别为Streptococcus thermophilus+Lactobacillus bulgaricus、EPS+S. thermophilus+L. bulgaricus和E. faecium AS8。结果表明,在贮藏期间,不同发酵乳样品具有不同的流变学性质。同时,补充添加EPS和原位EPS对发酵乳流变性能具有不同的影响。通过Sephadex G-100和Sephadex G-50的分离纯化,获得2种多糖,分别为AS8-1-EPS和AS8-2-EPS。AS8-1-EPS主要单糖组成为甘露糖、葡萄糖和半乳糖(分别占59.1%、26.8%、7.9%),还有含量很少的其他单糖;AS8-2-EPS主要单糖组成为甘露糖、葡萄糖、半乳糖和鼠李糖(分别占65.4%、21.3%、8.9%、4.4%)。红外光谱检测结果表明AS8-1-EPS和AS8-2-EPS均为杂多糖。     

Development of a non-target metabolomics-based screening method for elucidating metabolic and probiotic potential of bifidobacteria

Traditional in vitro screening assays for identifying probiotics often fail to provide a metabolomic overview of candidate strains. Thus, this work aimed to develop a non-target metabolomics-based method for screening bifidobacteria from a broad perspective. First, methods for extracting intracellular metabolites of bifidobacteria were compared. Methanol extraction with bead mill and sonication was selected as it yielded the highest metabolome signal intensity and coverage. Multivariate analyses revealed obvious differences in the intracellular metabolome between species/strains. Fourteen differential metabolites that have previously been reported to possess probiotic function were identified. Bifidobacterium animalis subsp. lactis Probio-M8 (M8) had significantly more intracellular lactose than other species/strains but showed lower cell density and viable counts in stationary phase. Adding lactose in the culture medium significantly enhanced the growth of M8 strain but not other tested bifidobacteria. This work provided a new screening method and practical data for selecting potential candidates for further validation.     

锡盟地区小尾寒羊副产物营养成分分析与评价

以锡盟地区小尾寒羊的心、肝、脾、肺、肾、大肠、小肠、胃（瘤胃、网胃、瓣胃、皱胃）及血液等副产物为研究对象，对其常规营养成分、氨基酸、脂肪酸以及矿物质含量进行分析与评价。结果表明：锡盟地区小尾寒羊各副产物营养成分含量（鲜质量分数）为水分含量68.86%～83.62%、蛋白质含量11.10%～19.92%、脂肪含量0.19%～16.93%、灰分含量0.45%～3.82%；各副产物经酸水解处理后测定，含天冬氨酸、亮氨酸、赖氨酸等17 种氨基酸，其中包含人体必需的7 种氨基酸，必需氨基酸占氨基酸总量的34.44%～44.35%，且谷氨酸、天冬氨酸、亮氨酸等含量丰富；各副产物中不饱和脂肪酸含量（除羊血8.26%外）为35.56%～56.09%，其中以单不饱和脂肪酸为主，网胃、瓣胃、皱胃、大肠、小肠中油酸含量均在30%以上，且网胃、肝脏、肺脏中亚油酸含量较高；各副产物中含有多种微量元素，其中脾脏中K和Fe含量最高，4 个胃中Ca含量均较高。     

茶多酚对羊肉肌原纤维蛋白凝胶特性的影响

研究茶多酚对羊肉肌原纤维蛋白凝胶特性的影响，将不同添加量（0.00%、0.01%、0.05%、0.10%、0.50%、1.00%）的茶多酚加入到羊肉肌原纤维蛋白中，测定肌原纤维蛋白表面疏水性、乳化性能、保水性、质构特性，观察羊肉肌原纤维蛋白凝胶微观结构。结果表明，与对照组相比，茶多酚添加量为0.10%时，羊肉肌原纤维蛋白的表面疏水性最小，疏水基团暴露程度最轻，乳化活性指数达到最大（4.88 m2/g），乳化稳定性指数（86.54%）和保水性（95.22%）均达到最佳；随着茶多酚添加量的增加，羊肉肌原纤维蛋白凝胶的硬度、咀嚼度、胶着度均显著上升（P＜0.05），弹性、内聚性、回复性整体呈下降趋势（P＜0.05）。结论：添加适量茶多酚可以显著改善羊肉肌原纤维蛋白的凝胶特性，并且凝胶的微观结构更加致密、空隙更小、形状规则且分布均匀；茶多酚与肌原纤维蛋白的非共价结合和共价结合可能会影响蛋白质的功能特性，并且这种作用强度随着茶多酚添加量的变化而变化。     

苏尼特羊不同部位肌肉抗氧化系统的差异

以放牧条件下的苏尼特羊股二头肌、臂三头肌和背最长肌3个部位的肌肉为材料,测定其丙二醛(MDA)、氧合肌红蛋白(OMb)、高铁肌红蛋白(MMb)含量、抗氧化酶活性(超氧化物歧化酶SOD、过氧化氢酶CAT、谷胱甘肽过氧化物酶GSH-Px)、抗氧化能力(降铜离子还原能力CUPRAC、自由基清除率RSA)、色差和pH值等指标,比较不同部位之间的差异。结果表明:抗氧化酶和抗氧化性能中,臂三头肌的SOD与GSH-Px活性最高,而背最长肌中的CAT活性、CUPRAC和RSA最高。背最长肌的pH值最高,而MDA、L*值、a*值和b*值均显著低于股二头肌和臂三头肌(P<0.05)。股二头肌中OMb显著高于臂三头肌和背最长肌(P<0.05),而MMb显著低于其它部位(P<0.05)。苏尼特羊肌肉中的抗氧化酶之间具有协同作用,且抗氧化酶活力的增强能提高机体抗氧化性能,降低氧化程度。整体上,苏尼特羊背最长肌中抗氧化物质含量较高,脂质氧化程度低于其它两个部位,抗氧化能力较强。     

黄河万家寨河段河冰冰厚遥感提取及年内变化特征分析

冰凌观测是防凌的前提,是冰凌研究的基础,因此全面准确的冰凌观测可为科学防凌提供可靠的依据。为此,以黄河万家寨库区河段为例,通过冰厚反演算法对其冰厚数据进行遥感反演,利用Lebedev模型对反演结果进行验证,并对结果进行年内变化特征分析。结果表明,卫星遥感反演结果与实测及模型验证结果接近,相关系数为0.8;冰厚演变总体呈成冰、流凌、初封、稳封、融冰、开河的生消演变过程。反演冰厚结果可为黄河内蒙段防凌减灾等实际工作提供参考依据。     

Modeling surface water-groundwater interaction in arid and semi-arid regions with intensive agriculture

In semi-arid and arid areas with intensive agriculture, surface water-groundwater (SW-GW) interaction and agricultural water use are two critical and closely interrelated hydrological processes. However, the impact of agricultural water use on the hydrologic cycle has been rarely explored by integrated SW-GW modeling, especially in large basins. This study coupled the Storm Water Management Model (SWMM), which is able to simulate highly engineered flow systems, with the Coupled Ground-Water and Surface-Water Flow Model (GSFLOW). The new model was applied to study the hydrologic cycle of the Zhangye Basin, northwest China, a typical arid to semi-arid area with significant irrigation. After the successful calibration, the model produced a holistic view of the hydrological cycle impact by the agricultural water use, and generated insights into the spatial and temporal patterns of the SW-GW interaction in the study area. Different water resources management scenarios were also evaluated via the modeling. The results showed that if the irrigation demand continuous to increase, the current management strategy would lead to acceleration of the groundwater depletion, and therefore introduce ecological problems to this basin. Overall, this study demonstrated the applicability of the new model and its value to the water resources management in arid and semi-arid areas.     

3种不同酵母产蓝莓酒风味物质的研究

利用3种不同酵母（T1、FK3-2、LM6）发酵生产蓝莓酒，并对其主发酵期的风味物质进行研究。气相色谱（GC）检测发现，酵母LM6发酵的蓝莓酒后期异丁醇、异戊醇和丁酸乙酯含量较高，分别为2.38 mg/mL、2.13 mg/mL、2.05 mg/mL。高效液相色谱（HPLC）检测发现，菌株LM6发酵的蓝莓酒在28 d时有机酸种类减少，草酸含量增加至3.17 mg/mL，L-苹果酸含量降至0.09 mg/mL、乳酸含量降至9.87 mg/mL，琥珀酸含量降至3.06 mg/mL。电子舌检测中发现FK3-2和T1酵母菌产生的酸味明显且所产风味相似；LM6酵母菌产生的风味较均衡，但鲜味、咸味及丰富性更明显。综合比较发现，LM6酵母菌更适合发酵蓝莓酒。