Correlation Between Oxidative Deterioration of Unsaturated Lipid and n-Hexanal during Storage of Brown Rice

n-Hexanal in the headspace over cooked brown rice stored at 5°C and 35°C for 0, 4, 8 and 12 months was determined by a gas chromatographic method using modified direct vapor injection. The off-flavors of stored brown rice were evaluated by n-hexanal and oxidized linoleic acid analysis. The amount of n-hexanal was found to be linearly proportional to the amount of oxidized linoleic acid (correlation coefficient, 0.99). Therefore, the simple and rapid method of vapor injection gas chromatography can be used for determining n-hexanal in the headspace vapor over cooked brown rice. Thus, the off-flavor of the stored brown rice resulting from lipid oxidation can be detected indirectly.     

Kinetic Parameters for Thermal Degradation of Green Asparagus Texture by Unsteady-state Method

An unsteady-state method was developed for estimating texture degradation during heating-cooling of green asparagus spears. The method used a mathematical model of heat transmission for time-temperature history estimation, and a nonlinear regression of texture measurements of asparagus spears to estimate kinetic parameters. The specific heat, conductivity and convective coefficient of green asparagus were determined experimentally and used in the mathematical model for temperature estimation. Values obtained were Ea = 76.19±0.13 kJ/mol and k_1158°C= 0.00528±0.00005 s^-1. Good agreement was found between predicted and observed texture values. The method was compared with the classical steady-state method. The mathematical model and kinetic parameters estimated could be used to design and evaluate thermal processes for green asparagus.     

INFLUENCE OF OSMOTIC DEHYDRATION ON THE VOLATILE PROFILE OF GUAVA FRUITS

ABSTRACT

The effect of osmotic dehydration (OD) on the volatile compounds of guava fruits was studied. Osmotic treatments were carried out at atmospheric pressure, at continuous vacuum and by applying a vacuum pulse (5 min under vacuum and the remaining time at atmospheric pressure) at different temperatures (30, 40 and 50C) and times (1, 2 and 3 h). The volatile compounds of fresh and dehydrated samples were obtained by simultaneous distillation–extraction, and were analyzed by gas chromatography/mass spectrometry. In general, OD caused changes in the concentration of volatiles, depending on the process conditions. The use of lower temperatures and shorter treatment times can diminish the loss of volatiles with respect to the fresh samples. The greatest damage to volatiles loss is produced at 50C for up to 2 h under both pulsed and continuous vacuum. The lowest total volatiles loss occurred at 30 and 40C for up to 3 h under pulsed vacuum or atmospheric pressure.

PRACTICAL APPLICATIONS

Consumer demand for high‐quality products with freshlike characteristics has promoted the development of a new category, minimally processed fruits and vegetables. Although these products present, as distinguishing features, simplicity in use and convenience, they generally perish more quickly than the original raw material because of tissue damage caused by mechanical operations. The use of osmotic dehydration process has been presented as a tool for the development of minimally processed fruits. The slight water activity reduction promoted by the process may provide stable products with good nutritional and sensorial quality and with characteristics similar to those of the fresh products. The application of minimal processing to tropical fruits can represent an interesting world market. Fruit flavor is an important quality factor that influences consumer acceptability, and for this reason, its study is relevant in the minimally processed food product.

     

Impact of SARS-CoV-2 infection during pregnancy on postnatal brain development: The potential role of glial cells

Glial cells are crucial for maintaining central nervous system (CNS) homeostasis. They actively participate in immune responses, as well as form functional barriers, such as blood-brain barrier (BBB), which restrict the entry of pathogens and inflammatory mediators into the CNS. In general, viral infections during the gestational period can alter the embryonic and fetal environment, and the related inflammatory response may affect neurodevelopment and lead to behavioral dysfunction during later stage of life, as highlighted by our group for Zika virus infection. Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) induces a cytokine storm and, during pregnancy, may be related to a more severe form of the coronavirus disease-19 (COVID-19) and also to higher preterm birth rates. SARS-CoV-2 can also affect the CNS by inducing neurochemical remodeling in neural cells, which can compromise neuronal plasticity and synaptic function. However, the impact of SARS-CoV-2 infection during pregnancy on postnatal CNS, including brain development during childhood and adulthood, remains undetermined. Our group has recently highlighted the impact of COVID-19 on the expression of molecular markers associated with neuropsychiatric disorders, which are strongly related to the inflammatory response. Thus, based on these relationships, we discussed the impact of SARS-CoV-2 infection either during pregnancy or in critical periods of neurodevelopment as a risk factor for neurological consequences in the offspring later in life, focusing on the potential role of glial cells. Thus, it is important to consider future and long-term public health concerns associated with SARS-CoV-2 infection during pregnancy.     

CHEMICAL CHARACTERIZATION AND PREPARATION OF SALTED MINCES FROM BIGEYE GRUNT AND LONGFIN BONEFISH

The proximate chemical composition, amino add and fatty add profile of bigeye grunt (Brachydeuterus auritus) and longfin bonefish (Pterothrissus belloci) minces were determined. Both minces contained a low fat content. Polyunsatu‐rated fatty adds represented more than 50% of the fatty adds in bigeye grunt but in the case of longfin bonefish the percentages of saturated, mono‐, and polyunsaturated were similar. The amino add profile of minces from these species was very similar. The preparation of salted minces using different drying methods is described. The chemical and physical characteristics of raw and dried salted minces as well as cooked products were measured. Dried salted minces from these species had high water uptake and cooked products presented a low salt content (1 %). Cooked rehydrated salted minces from longfin bonefish were lighter in color than those from bigeye grunt and color values were not significantly influenced by the salt level used in the preparation.     

GLASS TRANSITION AND TEXTURE IN A TYPICAL SPANISH CONFECTIONERY PRODUCT: XIXONA TURRON

The water sorption isotherm at 25C and glass transition temperature were determined in a typical Spanish confectionery product (Xixona turrón), as well as in the fat-free product. The samples were equilibrated at water activity levels from 0.113 to 0.755. The GAB and BET models were fitted to sorption data and the monolayer moisture contents were 2.8 and 6.0 (g of water/100 g of dried sample) for turrón and fat-free turrón, respectively. The sorption data indicate a lipid interaction with hydrophilic constituents. The analysis of the glass transition temperature (Tg) of the product as a function of its moisture content is used to determine the critical water content (CWC) at which the product becomes rubbery, at a determined temperature. From sorption isotherm at the same temperature (25C) we can also determine the critical water activity (CWA). The plasticizing effect of water in Xixona turrón can be modeled by the Gordon and Taylor equation. The fat also has a plasticizing effect, which is more obvious at low water content. A Texture Profile Analysis (TPA) was performed on samples with different moisture contents. Only samples with a moisture content lower than CWC showed fracturability, due to its glassy state. In the rubbery state hardness, gumminess and chewiness decrease when water content increases. Elasticity and cohesiveness increase in line with water content, more strongly for those moisture levels which are higher than BET monolayer value.     

稀土填充热电材料CoSb_3 Sm_x和CoSb_3 Pr_x的制备及表征

在低温熔融盐体系中,采用电沉积方法室温条件下制备Sm和Pr填充方钴矿化合物.研究不同稀土填充的方钴矿CoSb3热电材料的最佳制备工艺条件.通过扫描电子显微镜观察CoSb3Smx和CoSb3Prx的表面形貌,用特征X射线谱能确定其化学成分,用X射线衍射分析其晶型结构.优化工艺条件使稀土元素达到最大填充量.研究结果表明,合金薄膜的组成为Sm0.32CoSb3和Pr0.30CoSb3.三元合金薄膜由体心立方结构的CoSb3和六方晶形的稀土单质Sm组成.     

常村矿“十条线”“五星级”管理 推动采掘工作面安全质量标准化再上新水平

从2011年4月开始,常村矿对井下所有采掘工作面的安全质量标准化推行"十条线"、"五星级"管理,创建了多个精品采掘工作面,使全矿的安全质量标准化管理水平得到了进一步提升。     

内燃机气门锥面激光补焊工艺的探讨

本文报道用250W连续Nd∶YAG激光补焊机对内燃机气门锥面上的气孔进行补焊。探讨焊料、填料方式和激光作用时间对补焊成功率的影响。实验证明,这种补焊方法的成功率达到75％以上,获得了很大的经济效益。