Wet grinding characteristics of soybean for soymilk extraction

Wet grinding of hydrated soybean was carried out with mixer grinder, stone grinder and colloid mill which revealed that particle size had a profound effect on the protein recovery in the extracted milk with a maximum recovery of 89.3%. Greater reduction in particle size was achieved with mixer grinder (180 μm) with 5 min of grinding while reduction was not significant beyond 18 min (233 μm) in stone grinder. Specific energy consumption in colloid mill was only one-fourth of the mixer grinder while stone grinder required twice the energy. Although Kick’s, Rittinger’s and Bond’s laws could not be applied for total grinding duration, all the three classical laws were found suitable after the initial grain break-up period (2 min). Temperature and duration of thermal treatment given during hot extraction influenced protein recovery and viscosity of soymilk. The results suggest that colloid mill is a potential device for industrial scale operation.     

Hydration properties,soymilk and okara yield of soybean affected by agronomic factors

The effects of row space and irrigation on 100‐seed weight water uptake, leaching loss, soymilk, and okara yield of soybean were investigated. Row space affected leaching loss, whereas irrigation significantly altered 100‐seed weight, water uptake, volume change, leaching loss, and the soymilk yield of soybeans. Irrigation on the third day resulted in desirable hydration properties. The soymilk yield significantly correlated (p < 0.01 or 0.05) to the hydration properties, e.g., 100‐seed weight, water uptake, volume change, and leaching loss. A predictive regression model (R = 0.860) has been proposed for the soymilk yield.     

Isoflavone profiles of soymilk as affected by high-pressure treatments of soymilk and soybeans

High hydrostatic pressure was applied to hydrated soybeans (100–700 MPa, 25 °C) and soymilk (400–750 MPa; 25 and 75 °C) to assess its effect on isoflavone content, profile and water-extractability. Neither pressure level nor initial treatment temperature affected soymilk isoflavone content. However, combined pressure and mild thermal treatment modified the isoflavone distribution. At 75 °C, the isoflavone profile shifted from malonylglucosides toward β-glucosides, which was correlated to the effect of adiabatic heating. When pressure was applied to the hydrated soybeans, the soymilk isoflavone concentration varied between 4.32 and 6.06 μmol/g. The content of protein decreased and fat increased in soymilks prepared from pressurized soybeans with increasing pressure level.     

东北地区大豆主栽品种油份蛋白含量的关联分析

为探寻与大豆油份含量、蛋白含量相关的关键位点,本研究选取中国东北地区92份大豆主栽品种及常用种质资源品种群体基于蛋白含量和油份含量的Meta分析,进行基于数学模型的类群划分评价,估测样本群体的结构,应用简单线性模型分析与大豆油份含量、蛋白含量相关的的位点。结果表明,通过多次迭代测试,当K=5时,即该资源群体可以分为5个亚群时,为最稳定的分类结果,并在显著水平下（p〈0.05）贡献率大于1%的标记中,得到与大豆油份含量相关标记有Sat_412,Sat_195,Satt317,Sat_187,Sat_195,Satt255,Satt713,Satt468,Satt267,Satt686,Sat_294和AZ302047,对油分含量的总贡献率为39.54%。蛋白质含量相关标记有Satt683,Sat_311,Satt578,Satt181,Satt317,Satt700,Satt713,Satt255,Sat_242和Satt720对蛋白质含量总贡献率为48.39%。这些重要的标记位点为大豆油份含量和蛋白含量的分子辅助育种提供重要基础。     

Contrasting effects of high-pressure-assisted freezing and conventional air-freezing on eggplant tissue microstructure

 Damage to the microstructure of eggplants frozen by conventional air-freezing methods and by a high-pressure-assisted freezing method is compared in this paper. When conventional air-freezing techniques are employed, damage to the microstructure is enhanced as the freezing rate diminishes and the sample volume increases. However, when high-pressure-assisted freezing is applied, bulk nucleation occurs simultaneously in the whole sample, and the observed damage is less dependent on the volume of the sample. Received: 8 April 1997 / Revised version: 24 November 1997     

Effect of critical processing procedures on transgenic components in quality and quantity level during soymilk processing of Roundup Ready Soybean

By taking 2.5% (w/w) transgenic Roundup Ready Soybean as raw materials, with the detecting technology of traditional PCR and real-time fluorescence quantitative PCR, this study analyzed the influence of such critical processing procedures as jordaning, siruping, blending, homogenization and sterilization in soymilk preparation on the fragment size of endogenous gene lectin and exogenous gene epsps, as well as the quantification of transgenic component in Roundup Ready Soybean, and discussed the degradation mechanism of DNA in the course of transgenic soybean processing. The results indicated that, different processing procedures differ in their impact on the degradation of endogenous gene and exogenous gene. Physical mechanical action, such as the jordaning, can make endogenous and exogenous genes degrade, and has more effect on the later. The jordaning process degraded the DNA of endogenous gene from 1883 to about 836 bp, and exogenous gene from 1512 bp to about 408 bp. In the blending procedure, exogenous gene DNA was also degraded from about 408 to 190 bp, but there was no obviously action on the endogenous gene. After the endogenous and the exogenous genes were degraded to some degree, such as 836 and 408 bp, respectively, they were not evidently affected by siruping procedure at 100 °C for 15 min. However, endogenous gene was further considerably degraded from around 836 to 162 bp in the sterilization procedure at 121 °C for 30 s. The effect of the homogenization step on endogenous and exogenous genes was similar to that of siruping procedure. In addition, jordaning and siruping greatly damaged to exogenous gene, which rapidly decreased the transgenic content from 2.5 to 1.656% and 0.435%, respectively. While the endogenous gene was not evidently affected by the blending and homogenization procedures, the exogenous gene DNA was remarkably degraded in the two procedures. Therefore, the transgenic content continued decreased to 0.377% after homogenization procedure. Hereafter, the endogenous gene was further considerably degraded more than the exogenous gene in the sterilization procedure, which caused a little bounce of the transgenic content in the final product to 0.518%.     

Physicochemical characteristics and production of whole soymilk from Monascus fermented soybeans

Monascus fermented soybeans (MFS) were prepared by solid state fermentation. MFS showed higher solubility than the unfermented control within the acidic pH region but showed the opposite trend at pH 7 and 9. Although the emulsifying activity index of MFS was lower than that of the control, MFS had significantly higher emulsion stability at pH 7 and 9. Significant protein hydrolysis took place during fermentation, and the proportion of peak area less than 1.35 kDa was greatly increased in MFS. Whole soymilk prepared from MFS contained monacolin K (475 μg/g), and was enriched in isoflavone aglycones. Neither homogenisation nor pasteurisation caused significant changes in the isoflavone and monacolin K contents of the Monascus fermented soymilk. Total phenol content and ABTS radical scavenging activity were significantly higher in the Monascus fermented soymilk than in the control soymilk.     

Effects of freezing and frozen storage on the microstructure and texture of ewe's milk cheese

Semi-hard ewe's milk cheeses, frozen immediately after manufacture either slowly at –35 °C or rapidly at –80 °C and stored at –20 °C for 4 months were studied for microstructural and textural characteristics during subsequent ripening. Two control groups were used to establish the effect of freezing: the fresh unfrozen cheese and cheese thawed immediately after freezing. Freezing proper did not result in any marked changes in the textural parameters of the cheeses, but considerable changes were found in slowly frozen cheeses after 4 months of frozen storage. Shear strength values were lower in all frozen and stored cheeses, particularly in cheese samples frozen slowly compared to those in the unfrozen control batch. This parameter and firmness values were significantly lower in both slowly and rapidly frozen cheeses at the completion of ripening. Ripening tended to offset differences in elasticity, noticeable in the cheeses during the first 30 days of ripening. Light microscopy and electron microscopy revealed small cracks and ruptures in the cheeses which could not be observed by the naked eye. More extensive damage to the cheese microstructure was found in slowly frozen cheese samples stored frozen for 4 months.     

脂酶催化下大豆粉末磷脂与全氢化大豆油酯交换反应的研究

本文利用脂酶的特异性催化作用,研究了正己烷体系中,大豆粉末磷脂与全氢化大豆油的酯交换反应。利用碘值和产率为指标,考察了酶的种类及用量、底物摩尔比、温度、时间等因素对酯交换反应的影响,通过单因素和正交试验优化了大豆粉末磷脂与全氢化大豆油酯交换反应条件。发现在25%磷脂酶A1(以磷脂质量为基准)催化下,摩尔比4:1的全氢化大豆油和大豆粉末磷脂的正己烷溶液(磷脂浓度为0.20 g/mL),在50 ℃下反应24 h,得到产率为72.9%的改性磷脂。与原料磷脂相比,改性磷脂的碘值由89 g /100 g降至52 g /100 g,脂肪酸组成变化较大,硬脂酸含量约为原料磷脂的9倍,不饱和脂肪酸亚麻酸和亚油酸含量降低了约一半,实现了大豆粉末磷脂的结构修饰。     

Effect of thermal pretreatment of raw soymilk on the gel strength and microstructure of tofu induced by microbial transglutaminase

The influence of thermal pretreatment of raw soymilk on the gel hardness and microstructure of tofu, induced by microbial transglutaminase (MTGase), was investigated in this paper. Modulated differential scanning calorimetry analysis showed that individual proteins in soymilk were to a various extent denatured by different thermal pretreatments. The viscosity of the soymilk and the gel hardness of MTGase-induced tofu were more highly related with the heating rate (up to 90 °C) than the mode of heating. At any enzyme concentration of MTGase, the tofus prepared from soymilk heated at 75 °C for 10 or 30 min showed highest gel hardness among all tested ones (P?0.05). Scanning electron microscopy analysis indicated that the microstructure of the tofu from soymilk heated at 75 °C for 30 min had a unique coral-like structure, much more continuous and homogenous than that from soymilk at 95 °C for 5 min. These results confirmed that the appropriate heat pretreatment (e.g. in the present, at 75 °C for 10-30 min) remarkably improved the gel strength of tofu by means of MTGase, and strengthened the tofu gel structure.     

Effects of freezing temperature and duration of frozen storage on lipid and protein oxidation in chicken meat

This study examined the effects of freezing temperature and duration of frozen storage on lipid and protein oxidation in chicken leg and breast meat. The meat was frozen at three different temperatures (−7, −12 and −18 °C) and then stored at −18 °C for up to 6 months. A significant effect of frozen storage duration on lipid oxidation was detected in leg and breast meat, whereas freezing temperature had no significant effect. In leg meat, freezing at −7 °C had a significant impact on protein oxidation, measured as the increase in carbonyl groups and the decrease in total sulphydryl groups, after 3 months of frozen storage. Lipid and protein oxidation appeared to occur simultaneously in chicken meat during frozen storage and was more intense in leg meat than in breast meat.     

大豆籽粒不同发育时期基因表达谱分析

以花后15d的大豆籽粒作为对照,通过Solexa高通量测序方法对花后35d、55d和65d的大豆籽粒进行转录水平上的检测,并结合GO功能注释和pathway分析,共有差异表达unigene为9 905个,其中调控脂肪酸合成途径的显著差异表达基因12个,蛋氨酸代谢途径关键基因6个。以花后55d的cDNA为样本,荧光定量PCR检测了12个差异表达基因,其结果可与测序结果互为印证。     

High hydrostatic pressure effects on immunoreactivity and nutritional quality of soybean products

The aim of this research was to evaluate the protein pattern, immunoreactivity and amino acid composition of soybean seeds and commercial tofu after treating by high hydrostatic pressure (HHP) (300 MPa, 15 min, 40 °C), as well as of sprouts obtained from unpressurised and HHP-treated seeds. HHP did not affect the electrophoretic profile of soybean seeds or tofu protein extracts, but lower intensity of some protein bands were observed in HHP-treated products. A significant (P ? 0.05) reduced antigenicity was observed in the sprouts from HHP-treated seeds compared to the sprouts from untreated seeds, while higher antigenicity of the pressurised seeds compared with the untreated ones was found. HHP decreased the total essential amino acid content as well as two nutritional indexes, the Chemical Score (CS) and the Essential Amino Acid Index (EAAI), but only by 18%. The findings suggest that HHP applied to soybean seeds before germination could constitute a valuable technological approach for the industrial production of nutritive hypoallergenic soybean sprouts.     

Using power ultrasound to accelerate food freezing processes: Effects on freezing efficiency and food microstructure

Abstract

Freezing is an effective way of food preservation. However, traditional freezing methods have the disadvantages of low freezing efficiency and generation of large ice crystals, leading to possible damage of food quality. Power ultrasound assisted freezing as a novel technique can effectively reduce the adverse effects during freezing process. This paper gives an overview on recent researches of power ultrasound technique to accelerate the food freezing processes and illustrates the main principles of power ultrasound assisted freezing. The effects of power ultrasound on liquid food, model solid food as well as fruit and vegetables are discussed, respectively, from the aspects of increasing freezing rate and improving microstructure. It is shown that ultrasound assisted freezing can effectively improve the freezing efficiency and promote the formation of small and evenly distributed ice crystals, resulting in better food quality. Different inherent properties of food samples affect the effectiveness of ultrasound application and optimum ultrasound parameters depend on the nature of the samples. The application of ultrasound to the food industry is more likely on certain types of food products and more efforts are still needed to realize the industrial translation of laboratory results.     

Influence of freezing and of frozen storage on the specific heat capacity of trout and herring fillet

Effects of freezing and frozen storage on the specific heat capacity difference of native (not heat denatured) and heat denatured fillet () of trout and herring have been studied for the first time. Single and double freezing of fillet induced a clear reduction of the of up to 15 mJ g⁻¹ K⁻¹ at each freezing step. Frozen storage at −20 °C reduced the of herring fillet but not of trout fillet. This is in agreement with the earlier detected instability of myosin transition temperature of herring and the stability of myosin transition temperature of trout [1]. The is suggested as a new parameter for the evaluation of protein stability at freezing and frozen storage of fish. It has been shown, that a reversible endothermic effect between 2 and 22 °C in herring fillet is accompanied by a decrease of the storage modulus in the chopped fillet, which characterises the flexibility of the proteins. This mechanical change and the endothermic signal are missed in the chopped trout fillet at heating from 2 to 22 °C. This cold, reversible relaxation of fish proteins can be understood as a requirement for subsequent protein denaturation at frozen storage.     

The effects of okara on rat growth, cecal fermentation, and serum lipids

Okara, a soymilk residue, was characterized and used as a supplement to enrich dietary fiber in rats. Okara comprised 49% total dietary fiber, of which only 0.55% was soluble, protein (33.4%), fat (19.8%), and ash (3.5%). Okara as a diet supplement had no influence on food intake, but the growth rate and feeding efficiency were lower in the okara-fed group than in the control group. Okara increased fecal weight and moisture. In okara-fed rats, in vivo colonic fermentation of okara resulted in a lower pH, but a higher cecal weight and higher total short chain fatty acid production, compared to controls. There were no significant differences (P≤0.05) between groups in albumin, protein, uric acid, bilirubin, or glucose content in rat serum. The okara-supplemented diet produced a nonsignificant reduction in HDL-lipids and triglycerides. Okara, a rich source of low-cost dietary fiber and protein, might be effective as a dietary weight-loss supplement with potential prebiotic effect.     

Impact of high-pressure processing on microbial shelf-life and protein stability of refrigerated soymilk

The effects of pressure (400, 500 and 600 MPa), dwell time (1 and 5 min) and temperature (25 and 75 °C) on microbial quality and protein stability of soymilk during 28 days of storage (4 °C) were evaluated under aerobic and anaerobic conditions. After processing and during storage, there were significant differences in total bacterial count (TBC), numbers of psychrotrophs (PSY) and Enterobacteriaceae (ENT), and protein stability between untreated (control) and pressurized samples (P < 0.05). Pressure applied at an initial temperature of 75 °C resulted in a greater suppression in growth of PSY compared to TBC. No ENT was detected in pressurized samples throughout the storage period tested. Dwell time had no significant effect on log reduction of TBC at 25 or 75 °C (P > 0.05). Pressure at 400 MPa (5 min), 500 and 600 MPa (1 and 5 min) produced 100% sub-lethal injury in surviving bacterial populations irrespective of temperature. After 28 days of refrigerated storage, both aerobic and anaerobic pressurized samples had better or similar stability as the control on day one of storage. Soymilk control samples were spoiled after 7 days whereas pressurization increased soymilk shelf-life by at least 2 weeks. Pressure (600 MPa) at 75 °C for 1 min not only significantly reduced initial microbial populations and increased the microbial shelf-life but also extended the protein stability of soymilk (P < 0.05).     

Influence of freezing rate variation on the microstructure and physicochemical properties of food emulsions

The freezing rate used in industrial applications may vary for a number of reasons, such as changes in food mass, food composition, and freezing equipment operation. In this study, we evaluated the influence of freezing rates on the microstructure, stability and physicochemical properties of model emulsion-based sauces. Slow freezing (−0.015 °C/min) resulted in a larger mean particle size than fast freezing (−0.11 °C/min), which was attributed to increased fat droplet flocculation and coalescence. The influence of various additives (salt, sugar, gums) on the properties of the sauces was also investigated. The addition of 200 mmol/L NaCl promoted droplet flocculation and phase separation whereas 150 mmol/L sucrose inhibited droplet flocculation and phase separation, and inhibited ice crystal growth. The addition of 0.2% xanthan gum promoted flocculation, but inhibited phase separation and ice crystal growth. Our results are interpreted in terms of the influence of the additives on the phase behavior of water, and the colloidal interactions between the fat droplets. This study provides valuable information about the major factors, i.e., salt and sugar, and influence on the stability of emulsion-based products to freeze–thaw abuses, which has important implications for the development of high quality frozen meals.     

Influence of commercial freezing and storage on vitamin C content of some vegetables

Vitamin C levels of commercially frozen okra, potatoes, green beans, broccoli, spinach and peas, including the impact of processing and storage, were studied. Depending on the vegetable type, prefreezing operations caused a 19.1–51.5% decrease in the initial vitamin C levels. The freezing process alone did not influence the vitamin levels except in the cases of green beans and spinach. Total losses (%) were between 27.6 and 57.9 for the vegetables at the end of commercial frozen storage (6 months). All the data obtained from this study confirmed that, depending on the vegetable type, prefreezing operations have a major impact on the vitamin C contents and this influence persists in the frozen storage.