Roles of soluble and insoluble aggregates induced by soy protein processing in the gelation of myofibrillar protein

The role of soluble and insoluble aggregates induced by soy protein isolate (SPI) processing in the gelling properties of myofibrillar protein (MP) was studied. Incorporating soluble SPI aggregate could greatly improve (P < 0.05) the elastic modulus (G’) and water‐holding capacity (WHC) of MP gel, but had no notable effect on MP gel strength. In contrast, incorporating the insoluble SPI aggregate significantly enhanced the G’, strength and WHC of MP gel, although the improvement in WHC was smaller than that produced by the soluble aggregate. The results of environmental scanning electron microscopy showed that the soluble SPI aggregate induced a less randomly composite gel structure, which may explain its notable enhancement of WHC. However, the insoluble SPI aggregate appeared to be granules embedded in the continuous MP gel matrix, which may be related to the reinforcement of gel strength. Hence, the results of this study suggest further means of processing commercial SPI for use in meat products.     

Isolation,purification, and characterization of the globulin from wheat germ

This research optimized the extraction and purification of globulin from wheat germ and assessed the molecular weight distribution and structure properties of the globulin obtained. The results showed that the relative extraction efficiency and purity of wheat germ globulin (WGG) reached 18.0% and 89.1% under the enzymolysis conditions of 0.32‰ α-amylase, pH 6.5, and 55 °C. The maximal precipitation rate of WGG (91.3%) was obtained with pH 4.3 (acid precipitation). Additionally, the molecular weight of WGG was mainly distributed below 70 kDa. FT-IR confirmed that random coils (30.95%), β-sheet (27.02%), α-helix (26.55%), and β-turn (15.48%) were the secondary structures of WGG. Furthermore, LTQ mass spectrometry showed that WGG was rich in variety and high in complexity, which retrieved 1274 proteins belonging to 392 proteomes by inverse peptide analysis. The findings endow a great potential of preparing WGG with superior functionality for food applications.     

Investigation of hot air-assisted radio frequency heating as a simultaneous dry-blanching and pre-drying method for carrot cubes

Hot air-assisted radio frequency (HA-RF) heating was studied as a novel method for simultaneous dry-blanching and pre-drying of carrot cubes, and ultrasound-assisted osmotic dehydration (UOD) was also investigated as an improved conventional pre-drying method for comparison. After conventional hot water blanching, UOD was optimized by orthogonal experiment and after 30.0 min UOD treatment at optimal condition (10% sodium chloride, 40% sucrose and 1,4 solid-liquid ratio), moisture content of carrot cubes decreased to 58.5% (w.b.); and after 9.0–12.0 min HA-RF treatment, moisture content decreased to 60.9–71.9% (w.b.) and enzyme activity (peroxidase-POD) could be reduced to <5% at the same time. UOD was better in lowering water activity and retaining redness of carrot cubes, while HA-RF treated samples had higher vitamin C content and better texture. Besides, HA-RF pre-treatment had lower energy consumption (<0.20 kW∙h/kg) than that of hot water blanching plus UOD treatment (0.67 kW∙h/kg). This study indicated that HA-RF was an effective simultaneous dry-blanching and pre-drying method for carrot cubes.Industrial relevanceThis study proposed and investigated hot air-assisted radio frequency (HA-RF) heating as a new simultaneous dry-blanching and pre-drying method for carrots cubes. This technology may replace the conventional blanching and the following pre-dewatering or 1st stage drying process, since HA-RF pretreatment maintained good quality of carrot cubes and had lower energy consumption, and most importantly, this method can blanch and partially dehydrate samples at the same time without using water. Therefore, it holds great potential as the industrial pre-treatment method for drying of fruits and vegetables.     

Textural quality of sweet dumpling: effect of germination of waxy rice

Effects of germination on components and structural changes of rice flours and, in turn, rheological properties and textural attributes of sweet dumplings were investigated in this study. Germination decreased starch, protein and lipid content, while slightly increased free amino acids content. Starch granular surface corroded, crystalline structure disrupted, and short-range ordered structures and helical structures decreased with germination. Moreover, germination resulted in a decreased paste viscosity and gel intensity of flour and a reduction of hardness and adhesiveness of dumplings. According to the Pearson’s correlation analysis, flours components and starch structures were significantly correlated with flours rheological properties that determined textural attributes of sweet dumplings. The germination contributed to significant changes in flours components and starch structures, which suggested the pretreatment of germination of waxy rice could be a promising pathway to control textural properties of sweet dumplings.     

Comparative tarsal morphology of two secondary stored product beetle pests,Oryzaephilus surinamensis (L.) and Cryptolestes ferrugineus (Stephens), that vary in their climbing ability on smooth surfaces

Oryzaephilus surinamensis and Cryptolestes ferrugineus are serious secondary pests that infest commodities and packaged food. Both species differ in their climbing ability on smooth surfaces, such as the surfaces of packages or grains. In this study, we tested the hypothesis that tarsal and inter-claw adhesive structures of the species differ significantly. To test this hypothesis, we morphologically described and compared (quantitatively and qualitatively) the claws and setal structures on the tarsi and claws of O. surinamensis and C. ferrugineus using scanning electron microscopy (SEM). The main difference found was in the presence and/or quantity of tarsal and inter-claw adhesive structures between O. surinamensis and C. ferrugineus. The profound morphological differences regarding the presence and higher quantity of adhesive structures can explain why O. surinamensis is a better climber than C. ferrugineus on inclined smooth surfaces. The shape of the claws was similar in both species, but those of C. ferrugineus were slightly shorter and sharper (i.e., claw tip radius = 1.17 μm) than those of O. surinamensis (tip radius = 1.63 μm), indicating that C. ferrugineus is better morphologically adapted to move over rough material with smaller asperities. The obtained results suggest that the presence or absence of adhesive tarsal structures can be used for assessment of the ability of various pests to move on smooth surfaces of packaging or grains. The outcomes of the work may also provide inspiration to material and biomimetic scientists to improve pest-proof packaging material with anti-adhesive properties.     

Multi-wheat-model ensemble responses to interannual climate variability

We compare 27 wheat models' yield responses to interannual climate variability, analyzed at locations in Argentina, Australia, India, and The Netherlands as part of the Agricultural Model Intercomparison and Improvement Project (AgMIP) Wheat Pilot. Each model simulated 1981–2010 grain yield, and we evaluate results against the interannual variability of growing season temperature, precipitation, and solar radiation. The amount of information used for calibration has only a minor effect on most models' climate response, and even small multi-model ensembles prove beneficial. Wheat model clusters reveal common characteristics of yield response to climate; however models rarely share the same cluster at all four sites indicating substantial independence. Only a weak relationship (R² ≤ 0.24) was found between the models' sensitivities to interannual temperature variability and their response to long-term warming, suggesting that additional processes differentiate climate change impacts from observed climate variability analogs and motivating continuing analysis and model development efforts.     

Effect of thermal treatment on the characteristic properties of loach peptide

The effects of thermal treatment on the changes in the colour, the molecular weight distribution, amino acid profiles and the overall antioxidant activities of loach peptide were investigated. When the thermal temperature was rising, the browning was enhanced. The contents of free amino acids Gly, Arg, Thr and Tyr were increased, whereas those of Asp, Ser, Met, Cys, Trp and Lys were decreased. The scavenging activities (1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical scavenging activity, the oxygen radical absorbance capacity (ORAC) and the reducing power of loach peptides after different thermal treatments were lower than those of the control, whereas the Cu²⁺ chelating activity was higher (except from the sample treated at 100 °C, 20 min). The heat treatment at 121 °C, 15 min was shown to be the best thermal processing, as it caused the least loss in radical scavenging activity and showed relatively higher Cu²⁺ chelating activity.     

三种天然抗氧化剂对冷鲜兔肉保鲜效果研究

分别利用茶多酚,迷迭香提取物和植酸钠等天然抗氧化剂对冷却獭兔肉进行抗氧化及保鲜。结果表明:0.3g/kg茶多酚(TP),0.3g/kg水溶性迷迭香提取物及0.2g/kg植酸钠均可有效抑制冷鲜兔肉脂肪氧化,延缓氧化酸败异味的产生,从而有效延长冷鲜兔肉货架期,在(4±0.5)℃条件下达到9d左右;而空白对照组兔肉货架期仅为6d。     

Modelling of the inactivation kinetics of Escherichia coli,Saccharomyces cerevisiae and pectin methylesterase in orange juice treated with ultrasonic-assisted supercritical carbon dioxide

The combined effect of supercritical carbon dioxide (SC-CO₂) and high power ultrasound (HPU) on the inactivation kinetics of Escherichia coli, Saccharomyces cerevisiae and pectin-methyl esterase (PME) in orange juice was studied in order to select models that can predict their inactivation behaviour based on process parameters. Experiments were performed at different temperatures (31–41 °C, 225 bar) and pressures (100–350 bar, 36 °C). The inactivation rate of E. coli, S. cerevisiae and PME increased with pressure and temperature during SC-CO₂ + HPU treatments. The SC-CO₂ + HPU inactivation kinetics of E. coli, S. cerevisiae and PME were represented by models that included temperature, pressure and treatment time as variables, based on the Biphasic, the Peleg Type B, and the fractional models, respectively. The HPU-assisted SC-CO₂ batch system permits the use of mild process conditions and treatment times that can be even shorter than those of continuous SC-CO₂ systems.