Effect of microwave pre-treatment on physical quality,bioactive compounds,safety risk factor,and storage stability of peanut butter

Microwave, as a new heat treatment technology, has the characteristics of uniform and fast heating speed. It is an energy-saving technology known for improving oilseed product quality. Its efficiency mainly depends on the roasting power and time. However, the production of high-quality peanut butter using short-time roasting conditions are limited. Herein, we determined an appropriate microwave roasting power and time for peanuts and evaluated its impacts on the quality of peanut butter. Different roasting powers (400 ​W, 800 ​W and 1200 ​W) and times (4, 4.5, 5, and 5.5 ​min) were preliminarily tested. Among them, 800 ​W at 5 ​min was the most suitable. The roasting efficiency was further evaluated using color, sensory, bioactive compounds, storage stability, and safety risk factors of peanut butter produced from four peanut cultivars (Silihong, Baisha-1016, Yuanza-9102, and Yuhua-9414). The pre-treated butter obtained from three cultivars (Silihong, Yuanza-9102, and Yuhua-9414) with moisture content between 5% and 7.2% had a similar sensory score (6–7) as the commercial on a 9-point hedonic scale compare to the other. The color of the pre-treated peanut butter varies statistically with the commercial but remained in the recommended range of Hunter L1 values of 51–52, respectively, for high initial moisture peanut cultivars. The total polyphenol (35.20-31.59 ​± ​0.59 ​μmol GAE/g) and tocopherol (19.05 ​± ​0.35 ​mg/100 ​g) content in the butter obtained from three cultivars (Yuahua-9102, Yuhua, and Baisha-1016) and Silihong respectively, were significantly (P ​< ​0.05) higher than those in the commercial butter. The induction times of all pre-treated butter (19.80 ​± ​0.99–7.84 ​± ​0.07 ​h) were significantly (P ​< ​0.05) longer during storage at accelerated temperature than commercial samples. In addition, no benzo[a]pyrene was found in the pre-treated samples. Collectively, the microwave pretreated peanut butter was superior to the commercial one. These findings provided data support and a reference basis to promote microwave use for peanut butter production.     

The effect of compression and incision on wood veneer and plywood physical and mechanical properties

ABSTRACT

Drying takes the largest share of energy in plywood production, and varying moisture content of veneers necessitates re-drying that often leads to over-dry veneers with deactivated surfaces, which may promote imperfect bonding. In order to decrease the drying time, reduce the need for re-drying of veneers, and improve the quality of plywood, birch and spruce veneers were subjected to pre-treatment by cold compression, incision, or a combination of the two. The effects of pre-treatment on the veneer and plywood quality were assessed by standard tests. Compression had a beneficial effect on water removal of the wettest veneers (spruce sapwood (SW) and birch), but some thickness reduction was observed in the veneers as well as the finished birch plywood. Compression led to thickness reduction of spruce veneers, but had no effect on SW plywood thickness likely due to higher viscoelasticity. Both compression and the combination of incising and compression levelled the moisture variation within the compressed stacks. Incision improved the modulus of elasticity of birch plywood, shear strength of SW plywood, and both bending and shear strengths of heartwood plywood. Higher surface pressure decreased the drying time of spruce SW in both plain compression and combined incision and compression pre-treatment.     

苦楝采种育苗与丰产栽培技术

根据笔者的试验研究成果和生产实践结果,较系统地介绍了苦楝的采种、育苗技术以及丰产栽培技术。     

Improving quality of composted biowaste to enhance disease suppressiveness of compost-amended, peat-based potting mixes

Biowaste can be converted into compost by composting or by a combination of anaerobic digestion and composting. Currently, waste management systems are primarily focused on the increase of the turnover rate of waste streams whereas optimisation of product quality receives less attention. This results in low quality composts that can only be sold on bulk markets at low prices. A new market for quality compost could be potting mixes for horticultural container-grown crops to partially replace non-renewable peat and increase the disease suppressiveness of potting mixes. We report here on the effect of wetsieving biowaste prior to composting on compost quality and on disease suppressiveness against the plant pathogen Pythium ultimum of peat mixes amended with this compost. The increased organic matter and decreased salt content of the compost allow for significantly higher substitution rates of peat by compost. In this study up to 60% v/v compost peat replacement did not affect cucumber growth. However, disease suppressiveness of the potting mixes strongly increased from 31 to 94% when the compost amendment rate was increased from 20 to 60%. It was shown that general disease suppression for P. ultimum can only be effective when the basal respiration rate is sufficiently high to support microbial activity. In addition, organic matter of the compost should reach a sufficient stability level to turn from disease conducive to disease suppressive. Increasing the compost addition from 20 to 60% did not significantly affect plant yield, yield variation were due to differences in nutrient levels. It can be concluded that compost from wetsieved biowaste has high potential to replace peat in growing media for the professional market.     

不同前处理条件对动态光散射检测酪蛋白胶束粒径的影响

为了准确评价乳的稳定性和加工性能,探讨不同前处理条件对动态光散射检测酪蛋白胶束粒径的影响,研究了稀释液的种类(超纯水、钙咪唑缓冲液、模拟牛乳超滤液和牛乳超滤液)、稀释液温(4和25℃)和稀释液的放置时间(0~48 h)对脱脂乳中酪蛋白胶束粒径的动态光散射测试结果的影响,并将酪蛋白胶束粒径的动态光散射测试结果与冷冻透射电镜图像中测得的真实结果进行比较。研究发现以超纯水和钙咪唑缓冲液作为脱脂乳稀释液时,部分胶束发生解离,影响测试结果;采用牛乳超滤液及模拟牛乳超滤液作为稀释液时,胶束的微环境没有改变,反映了胶束的真实粒径及分布;放置24 h后,牛乳超滤液及模拟牛乳超滤液将产生颗粒;温度对测试有显著的影响(P0.05):4℃的样品用25℃的稀释液进行稀释后,动态光散射的计数率和粒径分别增大了16.6%和11.4%;25℃的样品用4℃的稀释液进行稀释后,计数率和粒径分别降低了16.1%和9.8%。结果表明酪蛋白胶束粒径的测试前处理较适宜的条件为:在与样品的温度相同条件下,以配置好后24 h内的模拟牛乳超滤液或牛乳超滤液(10 k Da超滤膜)作为脱脂乳的稀释液进行稀释。通过与冷冻电镜条件下测得的酪蛋白胶束粒径的真值比较,发现该前处理条件下酪蛋白胶束粒径的动态光散射测试结果的相对误差为-5.7%~1.8%,表明该样品前处理方法可用于动态光散射方法快速检测酪蛋白胶束粒径。研究结果为快速、准确地获取酪蛋白胶束的粒径信息,进而准确分析乳的稳定性及加工性能提供参考。     

Assessing air-drying and rewetting pre-treatment effect on some soil enzyme activities under Mediterranean conditions

Soil enzyme activities are useful indicators of soil quality as they are very sensitive to disturbance. Sample storage or pre-treatments could affect the results in these assays, which are normally determined in fresh samples, kept cold or frozen. The objectives of this study were to (i) evaluate the effect of air-drying or air-drying and rewetting on β-glucosidase, acid phosphatase and urease activities in soils from different locations, degradation status and sampling seasons, and (ii) assess if air-drying or air-drying and rewetting is an accurate sample storage and pre-treatment procedure for enzyme activities in soil quality evaluations under semiarid Mediterranean conditions. Our results showed that urease, phosphatase and β-glucosidase activities were hardly affected by air-drying of degraded and non-degraded soils from the two locations studied in all seasons. Short incubations (4, 8 and 12 d at 23 °C) of rewetted air-dried soil at 55% of water-holding capacity showed different patterns depending on the enzyme studied. Urease and β-glucosidase activities were relatively stable during incubation, with several significant (P<0.05) shifts up and down in some soils and samplings. However, acid phosphatase showed an increase in activity with incubation, of between 5% and 50% relative to air-dried samples. These increases followed no pattern and were unrelated to soil characteristics or sampling date. Hence, urease, phosphatase and β-glucosidase activities determined in air-dried soil samples seem to be representative of those obtained under field-moist conditions. In contrast, short incubations of rewetted soil samples can produce fluctuations in these enzyme activities, mainly of acid phosphatase, and estimations in these conditions are not so representative of field-moist soil values.     

Soil moisture pre-treatment effects on enzyme activities as indicators of heavy metal-contaminated and reclaimed soils

Heavy metal contamination can inhibit soil functions but it is often difficult to determine the degree of pollution or when soil reclamation is complete. Enzyme assays offer potential as indicators of biological functioning of soils. However, antecedent water content of soil samples may affect the outcome of biological measurements. In Mediterranean regions, for much of the year ‘field moist’ surface soil can have water content similar to that of air-dry samples. The objectives of this study were to: (1) determine the sensitivity of a range of enzyme assays to detect the degree of pollution from a heavy metal mine spill; (2) evaluate rewetting field-dry soil as a pre-treatment for enzyme assays; and (3) test multivariate analysis for improving discrimination between polluted, reclaimed and non-polluted soils. The Aznalcóllar mining effluent spill provided a unique opportunity to address these objectives. This accident released toxic, heavy metal-contaminated (As, Bi, Cd, Cu, Pb, Tl, Zn…) and acid tailings into the Guadiamar watershed (SW Spain) in 1998, severely affecting the riparian zone along more than 4000 ha. Contaminated soils were collected from the highly polluted upper watershed and less polluted lower watershed along with reclaimed soil at both sites. Enzyme activities (phosphatases, arylsulfatase, β-glucosidase, urease and dehydrogenase) were assessed on both field-moist samples and soils rewetted to 80% of water-holding capacity and then incubated at 21 °C for 7 d prior to the assay. The reclaimed soils had higher activities than polluted soils but, typically, 1.5-3 times lower levels of activity than the non-polluted soil. Regardless of the moisture pre-treatment, all enzymes showed significant effects due to pollution, with urease and β-glucosidase showing the greatest discrimination between degrees of contamination. In general, rewetting field-dried soils increased activities on non-polluted and reclaimed soils which improved discrimination with polluted soils. Another method to increase the potential of soil enzyme activities to detect soil contamination could be to combine them in multivariate analysis, which provides a more holistic representation of the biochemical and microbial functionality of a soil.     

棉籽壳不同预处理与平菇子实体中游离棉酚的含量

通过在100 ℃和126 ℃下灭菌及堆积发酵等处理的含87%棉籽壳的培养料来栽培平菇,然后测定平菇子实体中棉酚的含量,结果发现棉酚含量均在国家安全标准(≦0.02%即200 mg/kg)以内,其中以堆积发酵18 d的培养料栽培得到的平菇子实体棉酚含量最低,只有24.00 mg/kg.     

预处理对SFE提取月见草种子、被孢霉菌丝体油脂的影响

以月见草种子、被孢霉菌丝体为超临界流体萃取(SFE)的试验材料,研究了不同预处理条件(水分、粉碎度、粉碎方式)在不同萃取压力下对超临界流体萃取油脂得率的影响;确定粉碎度、粉碎方式、水分与油脂萃取之间的关系。     

食品中农药残留分析方法的研究进展

由于农药残留引发的食品中毒事件时有发生,食品安全已受到人们的广泛关注和重视。因此,加强对农药残留分析方法的研究和加大对农药残留的检测力度非常重要。对近年来食品中农药残留分析的样品处理和检测方法进行了较为全面的概述,提出了农药残留分析的发展趋势。