The House Mouse (Mus musculus L.) Exerts Strong Differential Grain Consumption Preferences among Hard Red and White Spring Wheat (Triticum aestivum L.) Varieties in a Single‐Elimination Tournament Design

Wheat (Triticum aestivum L.) plays a central role in the health and nutrition of humans. Yet, little is known about possible flavor differences among different varieties. We have developed a model system using the house mouse (Mus musculus L.) to determine feeding preferences as a prelude to extending results to human sensory analysis. Here, we examine the application of a single‐elimination tournament design to the analysis of consumption preferences of a set of hard red and hard white spring wheat varieties. A single‐elimination tournament design in this case pairs 2 wheat varieties and only 1 of the 2 is advanced to further tests. Preferred varieties were advanced until an overall “winner” was identified; conversely, less desirable varieties were advanced such that an overall “loser” was identified. Hollis and IDO702 were the winner and loser, respectively, for the hard red varieties, and Clear White 515 and WA8123 were the winner and loser, respectively, for the hard white varieties. When using the more powerful protocol of 14 mice and a 4?d trial, differences in mean daily consumption preferences of 2 varieties were separated at P‐values as small as 2 × 10^?8. The single‐elimination tournament design is an efficient means of identifying the most and least desirable varieties among a larger set of samples. One application for identifying the 2 extremes in preference within a group of varieties would be to use them as parents of a population to identify quantitative trait loci for preference.     

Effect of relative humidity on the store stability of spray-dried beta-carotene nanoemulsions

In order to overcome the limitations of liquid-base emulsion system, beta-carotene nanoemulsions stabilized by modified starch were spray-dried to powders after the emulsification process. The powders showed a good dissolution in water and the reconstituted emulsions had similar particle sizes with the fresh nanoemulsions. A 30 days storage test was carried out to investigate the effect of relative humility (RH) on the storage stability of beta-carotene powders at 25.0 °C. The beta-carotene degradation profiles over time were found to fit well with a Weibull model and also closely related to the film property of the matrix, moisture sorption property and glass transition temperature of the powder. The results showed that modified starches with lower film oxygen permeability had a higher retention of beta-carotene during storage. The glass transition temperature of powder in different RH also affected the rate of beta-carotene degradation. Overall these results provide useful information for choosing wall materials and storage conditions to protect nutraceuticals in delivery systems.     

Comparison of aromatic and phenolic compounds in cherry wines with different cherry cultivars by HS‐SPME‐GC‐MS and HPLC

To compare the influence of cultivars on the production of aroma compounds and polyphenols, eight cherry varieties (six sweet and two sour) were fermented into cherry wines, and their compositions were analysed. Results showed that by headspace solid microextraction coupled to gas chromatography–mass spectrometry (HS‐SPME‐GC‐MS), a total of twenty‐first aromatic compounds, mostly consisting of esters, acids, terpenoids and C₁₃‐norisoprenoids, were identified, and eleven polyphenols including five anthocyanins and six phenolic acids were quantified using HPLC. May Duck and Early Richmond wines contained significantly higher levels of phenolic acids (>42 mg L^?1) that were associated with high contents of chlorogenic and neochlorogenic acids and also relatively high amounts of octanoic acid and β‐damascenone (odour activity values ≥1000). Hongdeng, Zhifuhong and Bing wines were characterised by higher concentrations of anthocyanins (>41 mg L^?1) and also relatively higher levels of isopentyl acetate. Lapins and Governer Wcod wines were distinguished by lower concentrations of polyphenols and relatively higher contents of ethyl 3‐methylbutanoate.     

Spoilage of refrigerated (4 °C) Litopenaeus vannamei: cooperation between Shewanella species and contribution of cyclo‐(L‐Pro‐L‐Leu)‐dependent quorum sensing

The spoilage potential of Shewanella putrefaciens and S. baltica isolated from spoiled refrigerated Litopenaeus vannamei was evaluated by in vitro assays for trimethylamine oxide reduction, extracellular hydrolytic enzymes and biofilm formation, and in vivo inoculation into surface‐sterilised shrimp followed by microbial, biochemical and sensory analyses during storage for 5 days at 4 °C. S. baltica displayed higher spoilage potential than S. putrefaciens both in vitro and in vivo. Shrimp co‐inoculated with them had one‐day shorter shelf life than those mono‐inoculated, based on the results of bacterial density, volatile base nitrogen, trimethylamine, volatile organic compounds and sensory analysis, which strongly suggests cooperation of Shewanella species in shrimp spoilage. Exogenous cyclo‐(L‐Pro‐L‐Leu) boosted bacterial growth, extracellular protease and collagenase activities, and biofilm formation of S. putrefaciens and S. baltica at least before they entered the stationary phase, indicating that cyclo‐(L‐Pro‐L‐Leu)‐dependent quorum sensing, a recently suggested communication mechanism between them, contributes to the cooperation.     

CFD studies on natural convective heating of canned food in conical and cylindrical containers

Enhancing natural convective heat transfer in canned food sterilization is explored through modifications to container geometry and its orientation. A conical geometry, of equal volume and height as that of the cylinder, pointing either vertically up or down was considered. The non-Newtonian fluid, 0.85% w/w sodium carboxy-methyl cellulose (CMC), was taken as the test food material and its laminar flow behavior was investigated using computational fluid dynamics (CFD). The movement of the slowest heating zone (SHZ) temperature was tracked and compared for the three geometries. The SHZ temperature was observed to attain the final sterilization fluid temperature of 100 °C fastest for an upright conical geometry followed by the cylinder and the downward pointing cone. There is scope for enhancing the thermal sterilization process through geometry modifications but without mechanical agitation or rotation. Further, the geometry modification if non-uniform must be complemented by its suitable orientation.     

Non-destructive evaluation of apple maturity using an electronic nose system

Currently, random and destructive sampling techniques are used to evaluate apple quality. Thus there is need to develop a non-destructive technique to assess apple quality. Maturity indices such as starch index and puncture strength were used to categorize Gala apples into three maturity groups referred to as immature, mature and over mature fruits. Multivariate analysis of variance (MANOVA) of the electronic nose (EN) sensor data indicated that there were different maturity groups (Wilks’ Lambda F = 3.7, P < 0.0001). From the Discriminant analysis (DA), EN could effectively categorize Gala apples into the three maturity groups with the correct classification percentage of 83%.     

SLR算法在MRI中的模拟方法与实验研究

在磁共振成像中,运用Shinnar-Le Roux算法设计射频脉冲,不仅可以避免Bloch方程引起的非线性问题,而且能有效地抑制旁瓣激发,以获得理想的激发带宽.首先介绍了SLR脉冲设计思想,然后基于密度矩阵理论,应用计算机模拟方法对所设计脉冲的激发带宽进行模拟.最后,给出了测量射频脉冲激发带宽曲线的脉冲序列,并用MRI实验加以验证.     

Stabilization of the Single-Chain Fragment Variable by an Interdomain Disulfide Bond and Its Effect on Antibody Affinity

The interdomain instability of single-chain fragment variable (scFv) might result in intermolecular aggregation and loss of function. In the present study, we stabilized H4—an anti-aflatoxin B₁ (AFB₁) scFv—with an interdomain disulfide bond and studied the effect of the disulfide bond on antibody affinity. With homology modeling and molecular docking, we designed a scFv containing an interdomain disulfide bond between the residues H44 and L100. The stability of scFv (H4) increased from a GdnHCl₅₀ of 2.4 M to 4.2 M after addition of the H44-L100 disulfide bond. Size exclusion chromatography revealed that the scFv (H44-L100) mutant existed primarily as a monomer, and no aggregates were detected. An affinity assay indicated that scFv (H4) and the scFv (H44-L100) mutant had similar IC₅₀ values and affinity to AFB₁. Our results indicate that interdomain disulfide bonds could stabilize scFv without affecting affinity.     

Weight loss of frozen bread dough under isothermal and fluctuating temperature storage conditions

Evaporative weight loss from food leads to both loss of saleable weight and quality deterioration so it need to be minimized. The effect of isothermal and fluctuating conditions on frozen dough weight loss was measured and compared with kinetic, physical and artificial neural network (ANN) models. Frozen dough samples were regularly weighed during storage for up to 112 days in loose-fitting plastic bags. The storage temperatures were in the range of −8 to −25 °C with fluctuations of ±0.1 °C (isothermal), ±1, ±3 or ±5 °C about the mean. For each combination of temperature and fluctuation amplitude, the rate of dough weight loss was constant. The rate of weight loss at constant temperature was nearly proportional to water vapour pressure consistent with standard theories for evaporative weight loss from packaged foods but was also accurately fitted by Arrhenius kinetics. Weight loss increased with amplitude of temperature fluctuations. The increase could not be fully explained by either the physic model based on water vapour pressure differences or the kinetic model alone. An ANN model with six neurons in the input layer, six neurons in hidden layers and one neuron in the output layer, achieved a good fit between experimental and predicted data for all trials. However, the ANN model may not be accurate for product, packaging and storage systems different to that studied.