Low molecular weight compounds responsible for savory taste of Indonesian soy sauce

Indonesian soy sauce is made using only soybeans as the nitrogenous source. Moromi obtained from fermentation of yellow soybeans using Aspergillus sojae as the starter was investigated. The fraction with molecular weights of less than 500 Da obtained by stepwise ultrafiltration was then fractionated by several chromatographic procedures, including gel filtration chromatography and RP-HPLC. Several chemical analyses, CE profiles, and taste profiles were performed to obtain the most intense umami fraction. The main components eliciting or enhancing the umami taste present in the fraction were purified and identified by protein sequencing, ESI-MS, and (1)H NMR at 400 MHz. Besides free l-glutamic acid and aspartic acid, free aromatic amino acids such as l-phenylalanine and l-tyrosine may also play an important role in impressing savory or umami taste of Indonesian soy sauce at their subthreshold concentrations and in the presence of salt and free acidic amino acids. This is reported as a new phenomenon of the so-called bitter amino acids.     

Response of summer savory at two different growth stages to biochar amendment under NaCl stress

Salinity stress leads to various biochemical changes in plants. Biochar (BC) is a soil amendment that is derived from pyrolyzed organic materials. The aim of this study was to investigate the effect of BC on growth and some biochemical characteristics of summer savory (Satureja hortensis L.) under NaCl stress at two different growth stages. So, a pot factorial experiment based on completely randomized design was performed that comprised three levels of BC (0, 1 and 2% w/w of soil) and four NaCl levels (0, 40, 80 and 120 mM) with four replications. According to the results, by increasing the NaCl concentration chlorophyll a, b, total chlorophyll, carotenoid and polyphenol oxidase (PPO) decreased, whereas antioxidant activity, total soluble sugar and phenolic contents increased. The use of BC (especially 2% w/w of soil) under NaCl stress had the greatest effects on studied traits at the vegetative and flowering stages and significantly increased chlorophyll a, b, total chlorophyll, carotenoid and PPO activity. The results of this experiment confirmed the view that each stage of growth responses differently to NaCl stress and the use of BC due to sorption of NaCl and increasing osmotic adjustment can lead to summer savory protection against NaCl stress.     

Gas-liquid chromatographic determination of beta-asarone in wines and flavors.

Wine samples containing beta-asarone (cis-2,4,5-trimethoxy-l-propenylbenzene) are distilled; beta-asarone is extracted by hexane and then quantitatively determined by gas-liquid chromatography (GLC), using ethyl palmitate as the internal standard. The GLC procedure is rapid and yields precise and accurate results. Mass spectrometry confirmed the identity of the GLC peak as beta-asarone. The ultraviolet spectra of beta-asarone and its isomer were also determined.     

Specific fluctuations in the composition of lipoxygenase- and glycosidase-generated flavors in some cultivated teas of Assam

Variations of fatty acid compositions, glycosides precursors, and lipoxygenase and glycosidase enzymatic activities were used simultaneously to differentiate for nine genetically different cultivated teas, four seasonal changes, and the affect of leaf maturity. The muscatel flavor of second-flush teas was associated with increased activities of glycosidase and several terpenes, phenolics, and aliphatic compounds bound to glycosides, whereas high levels of fatty acids and lipoxygenase activity biosynthesized more green volatiles in monsoon teas. Sequential hydrolysis of lipids and lipoxygenase-mediated reactions, during withering and rolling, showed a 3-fold increase of hexenol, hexenal, and related volatiles, but they decreased to the levels of fresh leaf during drying. However, a 4-fold increase of the floral bend of volatiles found in black tea developed due to the hydrolysis of the glycoside precursors throughout processing stages. About 45 key volatiles were monitored for flavor superiority among different clones. Various parameters affecting yield of volatiles were optimized and recommended.     

Antioxidant activities and phenolic composition of extracts from Greek oregano,Greek sage,and summer savory

Oregano vulgare L. ssp. hirtum (Greek oregano), Salvia fruticosa (Greek sage), and Satureja hortensis (summer savory) were examined as potential sources of phenolic antioxidant compounds. The antioxidant capacities (antiradical activity by DPPH* test, phosphatidylcholine liposome oxidation, Rancimat test) and total phenol content were determined in the ethanol and acetone extracts of the dried material obtained from the botanically characterized plants. The ground material was also tested by the Rancimat test for its effect on the stability of sunflower oil. The data indicated that ground material and both ethanol and acetone extracts had antioxidant activity. Chromatographic (TLC, RP-HPLC) and NMR procedures were employed to cross-validate the presence of antioxidants in ethanol and acetone extracts. The major component of all ethanol extracts was rosmarinic acid as determined by RP-HPLC and NMR. Chromatography indicated the presence of other phenolic antioxidants, mainly found in the acetone extracts. The presence of the flavones luteolin and apigenin and the flavonol quercetin was confirmed in the majority of the extracts by the use of a novel (1)H NMR procedure, which is based on the strongly deshielded OH protons in the region of 12-13 ppm without previous chromatographic separation. This deshielding may be attributed to the strong intramolecular six-membered ring hydrogen bond of the OH(5)...CO(4) moiety.     

Apparatus used for small-scale volatile extraction from ethanol-supplemented low-salt miso and GC-MS characterization of the extracted flavors

An extraction apparatus was equipped with a nitrogen-flushing vessel to purge volatiles from a 10-g miso prepared solution at 40 degrees C, a reflux condenser to recover water, a coiled cold-trap to separate ethanol in advance, and a glass-lined stainless (GLS) trap filled with Tenax TA for flavor adsorption. Volatiles in the GLS tube were released with a thermal desorption device and condensed with a Micro-cryo trap prior to connection with GC and GC-MS for characterization. After analysis, a broad volatile profile comprising 9 categories of functional group and 97 identified compounds was achieved. As affected by ethanol supplementation for miso fermentation, most volatiles except alcohols and acetals in the low-salt products fermented with 5% NaCl and 7.5% ethanol were higher than those in the control products fermented with 9% NaCl and 0% ethanol and the high-ethanol supplemented products fermented with 5% NaCl and 15% ethanol. It reveals that supplementation of ethanol in miso at an appropriate level not only enabled a low-salt miso fermentation but also enhanced flavor formation.     

Phase behavior and component partitioning in low water content amorphous carbohydrates and their potential impact on encapsulation of flavors

The compositions at which amorphous ethanol-maltose-water mixtures exhibit liquid-liquid separation have been determined in the temperature range from 20 to 80 degrees C. At water contents below approximately 20% w/w two phases were observed, with the maltose-rich phase slightly richer in water. Partition coefficients of organic nonelectrolytes ranging in hydrophobicity from 1, 2-ethanediol and 1,2-propanediol to benzyl alcohol and propyl acetate have been measured for octanol/sorbitol, benzyl alcohol/sorbitol, and 1-butanol/sorbitol mixtures. Linear correlations were found between the log partition coefficients in the various solvent systems. Replacing water with sorbitol results in more organic partitioning into the octanol. Replacing octanol with benzyl alcohol or 1-butanol also results in more organic partitioning into the hydrophobic phase. The results establish a relationship with partition coefficients for octanol/water mixtures, which are well studied experimentally and for which predictive approaches exist. The implications of these results for flavor retention and encapsulation are discussed.     

Investigation of the retronasal perception of strawberry aroma aftersmell depending on matrix composition

The development of strawberry aroma aftersmell after consumption in aqueous and milk model systems was followed. A recently developed sensory approach was used to seize the qualitative, quantitative, and temporal aspects of aroma profile development. The results obtained from sensory evaluation were then correlated to analytical data, obtained by means of intraoral aroma detection using the buccal odor screening system (BOSS). A clear correlation was found between the sensory persistence of single odor impressions and the intraoral detectability of odorants by BOSS. For the strawberry aroma mixture it could be shown that BOSS is capable of selecting those odorants of a complex aroma mixture that elicit a certain aftersmell impression developing after a certain period of time in the oral cavity. Also, the changes in in vivo odorant persistence depending on changes in food matrix composition could be directly followed by means of BOSS.     

Effect of beta-cyclodextrin on aroma release and flavor perception

Binding and release of volatile compounds to and from beta-cyclodextrin were measured in model aqueous systems using static equilibrium headspace and dynamic headspace dilution. Beta-cyclodextrin decreased the static equilibrium headspace for some volatiles (e.g., ethyl octanoate and decanone) due to binding, but dilution studies demonstrated that binding was readily reversible. Dynamic release of hydrophobic volatile compounds was similar to that observed from emulsions. When beta-cyclodextrin was added to fat free yogurt, the release of a commercial lemon flavoring was modified and was similar to release from a regular fat yogurt. Sensory difference testing confirmed the release results. The data demonstrate that beta-cyclodextrin can be used to modify flavor delivery in both model and real systems; the effects in the latter are sensorially significant.     

Nutrition professionals' perception of the 'healthiness' of individual foods

OBJECTIVES: This paper describes the development of an online questionnaire for testing nutrition professionals' perceptions of the 'healthiness' of individual foods and the results of administering that questionnaire. The questionnaire was designed to produce a standard ranking of foods that can be used as a tool for testing nutrient profile models. DESIGN: The questionnaire asked respondents to categorise 40 foods (from a master list of 120) in one of six positions, ranging from less to more healthy. The 120 foods were selected to be representative of the British diet. The questionnaire was sent via email to nutrition professionals from the British Dietetic Association and the (British) Nutrition Society. RESULTS: Eight hundred and fifty responses were received. These responses were used to rank the 120 foods by the average score which they received from the nutrition professionals. A regression analysis was also carried out to examine the relationship between the scores awarded by the nutrition professionals and various features of the foods: their nutritional content, their average serving size, their frequency of consumption, whether they were drinks or foods, etc. Nearly 50% of the variance in the average scores was explained by the nutritional content of the foods. When other variables were included in the analysis the percentage of variance that was explained increased to 64%. CONCLUSIONS: The average scores of the foods produce a standard ranking, which can be used as a tool for validating and comparing nutrient profile models. The regression analysis provides some information about how nutrition professionals rank the 'healthiness' of individual foods.     

Lipid deposition on the tongue after oral processing of medium-chain triglycerides and impact on the perception of mouthfeel

Lipids between the tongue and palate strongly contribute to the sensory impact of a product. Mouthfeel is a sensory attribute responsible for distinguishing reduced fat from full fat food products. The aim of this work was to quantify the distribution, deposition, and retention of lipids on the tongue and palate upon oral processing and relate this to texture. The thickness of lipid deposition was measured in mouth by fluorescence. A trained panel evaluated the perceived intensity of samples to describe lipid Mouthfeel. The thickness of lipid deposition on the tongue shows spatial variation (10-100 microm) and stopped increasing after intakes higher than 8 mL of medium-chain triglycerides (MCTs). After 2 min, only 25% of the lipid deposition was retained on oral surfaces. A difference in the thickness of lipid deposition of 25 microm resulted in significantly different perception. This work describes the in-mouth behavior of food lipids and its influence on texture perception.     

无人农机作业环境感知技术综述

推进农业装备智能化能够有效解决农业劳动力短缺的问题。环境感知是农业装备智能化的首要条件。然而,农业环境的动态变化和非结构化特性限制了无人农机的环境感知能力。该文对无人农机的作业环境信息感知技术进行全面梳理,首先介绍了无人农机作业环境的典型要素和各类感知传感器,并分析了不同传感器的优缺点,然后分别从障碍物感知、作物行感知和农田边界及高程信息感知等方面,对无人农机作业环境信息感知技术进行归纳总结,最后讨论了无人农机作业环境信息感知技术面临的挑战及发展趋势,旨在推动环境感知技术在农业领域的应用,促进农业机械的智能化转型。     

感知要素与遥感数据结合的乡村景观分类研究

景观分类是对区域景观差异性的描述、制图以及评估工作进行的前提与基础。该研究以河北省曲周县第四疃镇和槐桥乡为研究区,遵循风景园林学、景观生态学和分类学的基本原则和理论依据,采用主观和客观相结合的方法,对村级尺度下的乡村景观进行分类。其中,客观分类方法基于高分辨率遥感影像、地形数据、土壤数据等多元地理数据,运用核密度分析方法进行分类;主观分类方法运用聚类分析法,依据对研究区实地调查获取的视觉景观以及中国著名田园诗词中对乡村景观意境描述所提炼的意象景观进行分类。结果表明:该研究构建了一种自下而上的乡村景观分类体系,将研究区景观类型分为3个乡村景观群、4个乡村景观区和55个乡村景观类以及108种乡村景观要素;并对乡村景观群、景观区、景观类和景观要素之间的空间联系进行了相应的解释,结果可为新时代乡村振兴发展战略中乡村景观规划设计和美丽乡村建设提供理论和实践基础。     

基于农户感知的生态补偿效应分析*--以黑河中游张掖市为例

生态补偿作为一种将外在的、非市场环境价值转化为当地参与者提供生态系统服务的财政激励机制引起了世界关注。本文以黑河中游张掖市为研究区,以退耕还林工程为例,基于农户调查资料,采用模糊综合评价方法评价了农户感知到的生态补偿的社会效应、经济效应和生态效应,并采用最小二乘法分析影响农户对生态补偿效应感知的因素。结果表明:农户感知到的生态补偿效应指数达3.02。其中农户感知到生态补偿的生态效应最高,效应指数为3.11,生态补偿的社会效应次之,效应指数为3.06,经济效应最低,效应指数仅为2.55。这充分说明,生态补偿的实施实现了改善当地生态环境的主要目标,然后是缓解贫困、促进就业、发展经济等副目标。户主受教育程度、农户生计方式、年收入均与其感知到的生态补偿社会效应、经济效应、生态效应呈正相关,而户主年龄与其感知到的生态补偿效应均呈负相关。此外,农户的社会地位对其感知到的生态效应有显著影响。感知社会效应的因素中,户主受教育程度对社会效应感知的影响程度最大,相关系数达1.067,其次是农户生计方式,户主年龄对社会效应感知的影响相对较小;感知生态补偿经济效应的因素中,户主受教育程度对经济效应感知的影响程度最大,相关系数达1.073,其次是农户年收入和农户生计方式,户主年龄对经济效应感知的影响相对较小;感知生态补偿生态效应的因素中,户主受教育程度对生态效应感知的影响最大,相关系数达2.612,其次是农户生计方式,农户社会地位对其影响相对较小。     

生计资产对规模养猪户环境风险感知的影响实证

环境风险感知是养猪户对农村环境风险的态度和直觉判断,是风险应对行为的基础,而生计资产又是养猪户抵御风险、提高脆弱应对能力的保障。为研究规模养猪户生计资产与环境风险感知的关系,在对湖北、河南、广东、广西、江西、天津6省(市)规模养猪户运用参与式农村评估法(PRA)进行实地调查的基础上,应用统计分析和有序多分类Logistic模型,实证分析生计资产差异对规模养猪户环境风险感知的影响。结果表明:1)规模养猪户对环境污染、环境政策和环境治理的感知水平有明显差异。2)人力资本、自然资本和社会资本对环境风险感知有显著影响,金融资本和物质资本的影响较小。3)人力资本中年龄和受教育程度对环境风险感知的影响最大,相关系数分别为1.784和2.686;自然资本中地形对环境风险感知影响最显著,相关系数为1.813;社会资本中与周围农户的合作以及与周围农户关系的友好程度对环境风险感知有显著负向影响,相关系数分别为?0.950和?0.973;金融资本和物质资本对环境风险感知的影响则较小,模型估计仅通过10%水平的显著性检验。最后,基于实证结果,从建立科技示范与培训、环保知识宣传、法律法规体系建设、拓宽收入渠道等方面提出建议措施,旨在促进养猪户环境风险感知水平的提高和环境风险防御能力的增强。     

Study of interactions between food phenolics and aromatic flavors using one- and two-dimensional (1)H NMR spectroscopy

Changes in flavor release and aroma characteristics in a medium including food phenolics may be attributed to an intermolecular interaction between flavor compounds and phenolics. To investigate the interaction, one- and two-dimensional NMR studies have been carried out on the binding of two phenolics, gallic acid and naringin, with three aroma compounds, 2-methylpyrazine, vanillin, and ethyl benzoate. Evaluation of thermodynamic parameters and intermolecular nuclear Overhauser effects reveals that gallic acid can interact more strongly with aromatic flavors than naringin. The supramolecular complexation is also dependent on the structural nature of the flavors, with 2-methylpyrazine and vanillin interacting more strongly than ethyl benzoate. The interaction is principally pi-pi stacking between the galloyl ring and the aromatic ring of the aroma compounds, but secondary hydrogen-bonding effects help to stabilize the complex and enhance the specificity.