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关键词： Antioxidant capacity   Fatty acids   Rancimat   Ricinus communis   Tocols  

摘要： The aim of this research was to assess the physico-chemical properties and shelf-life of oils press-extracted at two temperatures (60 degrees C and 80 degrees C) from five Peruvian castor bean ecotypes. A wide variation for all traits was observed. Low acidity index, low peroxide index and absence of p-anisidine were recorded. The total tocopherol contents ranged from 798 to 1040 mg/ kg. A higher antioxidant capacity was detected in methanolic extracts than in hexane extract. From the Rancimat performed at 150-170 degrees C, the predicted shelf-life at 25 degrees C ranged from 0.15 to 8.93 years;the higher extraction temperature led to a longer shelf-life, probably because of enzyme inactivation.

关键词： Carnauba wax   1-Docosanol   Rheology   Oil binding ability   Astaxanthin bioaccessibility  

摘要： In this study, binary systems of carnauba wax (CW) and 1-docosanol (DS) were first explored to enhance the properties of oleogels. Compared to the corresponding single component oleogels (0:5 and 5:0), a synergistic effect of oleogel strength was observed at CW:DS ratios of 1:4 (C1D4). At this ratio, the formed oleogel showed the highest hardness, rheological property and oil binding ability. Meanwhile, the gel-sol melting temperature of this oleogel at this ratio was lower than most of others. Subsequently, the effect of composite gelators on the astaxanthin delivery of oleogel-based nanoemulsion was explored. The oleogels at CW:DS ratios of 1:4, 0:5 and 5:0 were chosen to prepare oleogel-based nanoemulsions. The oleogel-based nanoemulsion formulated with C1D4 had the largest droplet size. In vitro digestion study revealed that although C1D4 oleogel-based nano -emulsion could not improve the extent of lipolysis, it could significantly improve astaxanthin bioaccessibility when compared with the other two oleogel-based nanoemulsions. This study developed a new formula of oleogel-based nanoemulsion with improved astaxanthin bioaccessibility. This novel formulation approach might also be suitable for other hydrophobic nutraceuticals and provided a new idea for the preparation of oleogel-based nanoemulsions with improved nutraceutical bioaccessibility.

关键词： antioxidant activity   chitosan   conductivity relaxation time   curcumin nanoemulsion   electrical modulus   glass-transition temperature   Havriliak-Negami equation   water vapour permeability  

摘要： Chitosan (CH)-based films were incorporated with a curcumin nanoemulsion (CurNE) to overcome their limitations, such as low mechanical strength and high-water vapour permeability (WVP). The obtained optimum conditions of NE were, as follows: oil to aqueous phase ratio = 1:9 and ultrasonication time = 15 min, given that the smallest mean diameter and the highest absolute value of the zeta potential were 307.53 +/- 6.30 nm and -15.43 +/- 0.74 mV. Thereafter, NE was encapsulated in CH(CH-NE) to determine the functional amelioration, as well as the alteration in the inner structure. CH-NE demonstrated the successful fabrication of uniform and compatible films, which reinforced elongation and significantly decreased the WVP. Furthermore, the antioxidant activity of CH-NE was five times higher than that of CH. The thermal and electrical properties were evaluated to elucidate the alterations in the inner structure alterations. Further, the glass-transition temperature (T-g) of CH-NE shifted by similar to 10 degrees C and the relaxation time (tau) of the electric modulus increased compared with that of CH, indicating that the incorporation of NE affected the structural alterations.

关键词： Moisture  

摘要： Paneer (Indian cottage cheese) is a highly perishable commodity with short shelf-life which restricts the farmers from stocking up yak milk paneer and marketing their products in the high-altitude regions. Therefore, it is meaningful to establish shelf-life prediction models (Arrhenius model and modified Gompertz model) based on physicochemical and microbial qualities of vacuum-packed yak milk paneer under different storage conditions. With the increase in storage duration, all the physicochemical and microbial qualities of vacuum-packed yak milk paneer were affected significantly (p<.05) for both P-1 (76 mu) and P-2 (127 mu) packages under a temperature range of 8-24 degrees C. Arrhenius model showed the following order of susceptibility of physicochemical parameters to temperature change, i.e., pH>tyrosine value>titratable acidity>total free fatty acid>moisture content and titratable acidity>tyrosine value>pH>moisture content>total free fatty acid in P-1 and P-2 package, respectively. According to modified Gompertz model (R-2 >= 0.79), the highest microbial growth (mu(max)) was observed for P-1 package at 24 degrees C. Practical applications To explore the wider consumer palate, yak milk paneer was prepared and evaluated under different storage conditions by using predictive modeling, i.e., Arrhenius model and modified Gompertz model. Therefore, this approach could be advantageously used to predict the influence of packaging materials and storage conditions of dairy products whose quality is strictly related to growth of spoilage microorganisms.

关键词： ester reduction   ether   low viscosity   lubricant base stock   tribology  

摘要： A series of 2-ethylhexyl alkyl ethers (EHAE) are synthesized from palm-based esters via a one-step reaction under mild reaction conditions for potential usage as biolubricant. In this work, 2-ethylhexyl esters with varying fatty acid chain lengths are reacted with 1,1,3,3-tetramethyldisiloxane (TMDS), catalyzed by indium bromide (InBr3) at 40 degrees C to afford EHAE with lauryl, palmityl, stearyl, and oleyl alkyl chain with 55-68% isolated yield. These compounds are characterized using Fourier-transform infrared (FTIR) and NMR spectroscopic methods and are evaluated for their viscosity, thermal, cold-flow, oxidative, and anti-wear properties. The synthesized EHAEs demonstrate low viscosity (1.65-2.55 cSt at 100 degrees C) with excellent viscosity indices (130-182). These EHAEs show comparable wear scar diameter (0.6-1.0 mm) in comparison with commercial mineral oil base stock (group I SN150) in the four-ball wear test. Thermal-oxidative investigation of the EHAE reveals that the thermal degradation temperatures are in the range of 200-250 degrees C and oxidation onset temperatures are between 165 and 184 degrees C. Among the EHAEs, 2-ethylhexyl lauryl ether with the shortest alkyl chain has the lowest pour point of -27 degrees C. The physicochemical properties of synthesized EHAEs indicate that they are potential as biolubricant base stocks.

关键词： Amylosucrase   Enzymatic modification   Potato starch   Branch-chain length   Starch properties   Deinococcus geothermalis  

摘要： Branch-chain elongated starches can be synthesized by amylosucrase (AS). In this study, potato starches with different branch-chain length were produced using the temperature-dependent elongation property of AS from Deinococcus geothermalis (DGAS). Decreasing the reaction temperature led to a significant rise in the length of the branch-chains, in addition to amylose content. As branch-chain length increased, B-type crystal structure increased significantly alongside it, and the thermal transitions were enhanced, suggesting that the crystalline structure was further stabilized. In addition, a decrease in solubility and swelling power was observed, whereas the gelatinization temperatures and peak viscosities increased accordingly. With respect to digestive properties, a remarkable rise in slowly digestible starch (0-19.8%) and resistant starch (38.2%-62.2%) contents was observed, along with an enhanced resistance to mammalian mucosal alpha-glucosidase. In conclusion, enzymatic modification by DGAS might be an innovative method to regulate the physicochemical and digestive properties of starches.

关键词： physicochemical properties   rheological behavior   starch lychee seeds   thermal characteristics   ultrasonication  

摘要： High-power ultrasound (HPU) is a non-thermal processing method that has been researched and used in the last years. The application of ultrasound can modify and improve some technologically important compounds such as starch. This research aimed to examine the effect of ultrasound treatment on yield, physicochemical, and functional properties of lychee seed starch (LS). HPU experimental conditions used were sonication time (5 and 20 min) and amplitude (40% and 70% ). Starch yield significantly increased with increasing ultrasound amplitude and time. The ultrasound did not change the morphology and shape of the granules but caused cracks in their surface. Surface damage induced an increase in amylose content, relative crystallinity, enthalpy of gelatinization, swelling power, solubility index, and acid hydrolysis of the starch. These results indicate that ultrasound mainly affected the amorphous starch region. The morphology, size, color, rheological and thermal characteristics, crystal structure, and structural order features of the untreated and ultrasound-treated LSs were compared. A principal component analysis was carried out to assess the effect of the ultrasound treatment on LS characteristics.

关键词： Psyllium fibre   Hydration properties   Functional capacity   Gelling properties  

摘要： Psyllium fibre has known health benefits, which are highly related to its gelling properties, so it is important to know the functional properties and its gelling capacity to its possible incorporation as a new source of DF in foods. Therefore, the purpose of this research was to evaluate these properties of two Psyllium fibres. Physicochemical (particle size distribution, pH, water content, water activity, hygroscopicity and bulk density and porosity), hydration (water holding, water retention and swelling capacity, fat absorption capacity and solubility), and nutritional properties (mineral content, total phenolics compounds and antioxidant capacity) of dietary fibre (DF) samples were recorded. Moreover, physicochemical (water content, pH and colour) and mechanical properties (back extrusion test, rheological measurement and texture profile analysis) of gel samples were performed before and after heat treatment (20 min at 65 degrees C). The hydration properties of Plantago Husk (PH) were higher than those in Plantago Powder (PP), but in functional terms, high values of phenols and antioxidant activity were found in PP. However, both samples displayed similar gelling properties. As a result of the rheological and textural analysis, both fibres showed good gelling properties at both high (65 degrees C) and cool (5 degrees C) temperatures, at concentrations 4%-7%. Moreover, the results indicate that PH and PP have suitable characteristics to be functional ingredients, which can help to avoid possible negative effects on food sensory and structural characteristics.

关键词： Chitin  

摘要： The black soldier fly prepupae (BSFP) emerged as a sustainable and novel nutritional source with high protein, lipid, chitin, and micro-nutrients. The study focused on defatted BSFP flour with increased protein concentrate and less-fat, which has high demand in current trend. The defatted FD BSFP flour has promising amount of protein (44.63%), low-fat (1.18%) with high caloric value (400.04 kcal) compared with SD BSFP flour. Interestingly the chitin (18.22%) and fiber (9.29%) compound was found to be higher in defatted SD BSFP flour. The SEM image revealed the morphology of smooth globules and compact agglomerated structure in FD SD BSFP flour, respectively. The DSC thermogram revealed optimistic thermal properties in both FD and SD BSFP flours. The study depicts the suitability of FD BSFP flour for mass commercialization as a novel functional ingredient in food and feed products. Novelty impact statement Defatted BSFP flour provides a higher protein concentrate and chitin components by limiting the number of individual extraction processes thereby reducing the price of production. The defatted FD BSFP flour can be used as a novel and alternative source for protein and chitin derived from a hitherto underused insect. The thermal stability of both the FD and SD BSFP defatted flours revealed a promising approach for biopolymers, which can withstand high temperature.

摘要： 2023年全国报刊杂志征订工作已经开始，敬请向贵单位推荐订阅2023年《物理化学学报》。《物理化学学报》是由中国科学技术协会主管，中国化学会和北京大学共同主办，北京大学化学与分子工程学院学报编辑部编辑出版的学术刊物。设有“通讯”、“展望”、“专论”、“综述”、“论文”等栏目，报导物理化学学科及交叉学科的基础研究及应用研究的创新成果。