Linking peanut allergenicity to the processes of maturation,curing, and roasting

The processes of peanut maturation, curing, and roasting are known to have an important role in peanut flavors. One of these processes (i.e., roasting) has been found to have an effect on allergenicity. To determine if the other processes (i.e., maturation and curing) affect allergenicity, mature and immature roasted peanuts and peanuts cured at different temperatures (35-77 degrees C) were, respectively, tested for IgE binding and advanced glycation end adducts (AGEs). Peanuts with and without stress proteins, which are associated with peanut maturation and curing, were also tested. Results showed that mature roasted peanuts exhibited a higher IgE binding and AGEs level than immature roasted peanuts. Curing temperatures between 35 and 60 degrees C gave no difference in the profiles. However, a higher curing temperature (i.e., 77 degrees C) exhibited a profile of higher levels of AGEs and IgE binding. These levels were higher in peanuts with stress proteins than without stress proteins. Roasting increased stress protein level and IgE binding. From these results, the processes of maturation and curing, in conjunction with roasting, may be associated with allergenicity, suggesting that these processes may lead to changes in the allergenic properties of peanuts.     

热风、微波及其联合干燥对花生营养特性及感官品质的影响

为了降低花生收获后因未及时干燥而造成的霉变损失,本试验以天府9号新鲜花生为试验材料,采用热风、微波、微波热风联合干燥3种技术对花生进行干燥,对比了3种干燥方式对花生营养及感官品质的影响。结果表明,热风、微波及热风微波联合干燥将花生干燥至安全含水率耗时分别为24、14和10 h。微波热风联合干燥花生的氨基酸、脂肪以及不饱和脂肪酸含量均显著高于热风、微波2种干燥方式(P<0.05),而酸价及过氧化值显著低于热风、微波2种干燥方式(P<0.05),且其色泽与花生自然果色最为接近,颜色均匀一致,红衣完整无皱缩脱落,风味较好。本研究结果为花生机械化干燥提供了一定的理论基础,在花生产地减损领域中具有较好的应用价值。     

Identification of fruity/fermented odorants in high-temperature-cured roasted peanuts

Gas chromatography/olfactometry on a concentrate of volatiles obtained by solvent-assisted flavor evaporation (SAFE) from roasted peanuts containing a fruity/fermented off-note was used to identify the odorants responsible for the flavor defect. Freshly dug peanuts were divided into two classes, mature and immature, using pod mesocarp color, and subjected to normal (27 degrees C) and high (40 degrees C) temperature curing. Sensory evaluation of the roasted peanuts found that immature peanuts cured at high temperature contained the fruity/fermented off-note. Mature peanuts cured at high temperature and both immature and mature peanuts cured at low temperature were free of the off-note. Peanuts with the off-flavor were found to contain fruit-like esters (ethyl 2-methylpropanoate, ethyl 2-methylbutanoate, and ethyl 3-methylbutanoate) along with increased levels of short chain organic acids (butanoic, 3-methylbutanoic, and hexanoic). These findings were confirmed by sensory evaluation of models, where the addition of these compounds produced the fruity/fermented flavor defect in a control peanut paste. This is the first time that the odorants responsible for this off-note in roasted peanuts have been identified.     

收获时期及干燥方式对花生品质的影响

为探索不同收获期和后熟干燥方式对花生品质的影响,该研究以泰花5号花生为试验对象,采用在株晾干法、鲜摘晾干法、鲜摘催干法3种方法对3个时期收获的花生进行后熟干燥品质对比测试分析。结果表明,在同一收获期中,在株晾干法花生百果质量、百仁质量显著高于其他2种方法,该后熟干燥方法的增重作用随收获期提前而更明显(P0.05);但在相同后熟干燥方法中,提前2周收获的干燥荚果百果质量、百仁质量均显著低于前1周和原定收期收获的花生荚果(P0.05)。自然晾晒干燥期间,在株晾干花生果壳、果仁含水率均高于同期鲜摘晾干果壳、果仁含水率,两种晾干方式含水率差异在初期逐渐增加、随后逐渐减小直至达到相当的最终含水率。鲜摘晾干和鲜摘催干果仁粗蛋白、粗脂肪均未见显著差异(P0.05),而在株晾干果仁粗蛋白、粗脂肪含量分别增加了3%、2%左右;而收获期越早,果仁粗蛋白和粗脂肪含量越低。在果仁不饱和脂肪酸总相对含量上,鲜摘晾干、在株晾干果仁与新鲜果仁未见差异(P0.05),但机械催干果仁显著低于新鲜果仁(P0.05)。在果仁氨基酸组成方面,经3种不同后熟干燥方法后,8种主要氨基酸及氨基酸总含量均呈现在株晾干含量最高、鲜摘晾干其次、机械催干最低的差异(P0.05)。在株晾干花生果柄横断面显微结构观察表明,果柄在干燥初期仍保留对水分、养分等物质输导、贮藏的空间通道,为荚果的物质代谢和积累提供必要条件。该研究结果为花生生产实践提供参考。     

Composition,Nutritional Value,and Health Benefits of Pulses

The United Nations has declared 2016 as the International Year of Pulses. Pulses are narrowly defined as leguminous crops that are harvested as dry seeds. Although some pulse crops are harvested green (e.g., green peas), these are classified as vegetables because the pods are often consumed along with the mature and sometimes immature seeds. Other dried legumes such as soybean and peanut meet the definition of being a leguminous crop that is harvested as dry seeds; however, these crops are grown primarily for oil content and, thus, are not categorized as pulses. There are hundreds of pulse varieties grown worldwide; these include, for example, dry edible beans, chickpeas, cowpeas, and lentils. This review will cover the proximate (e.g., protein, carbohydrates, vitamins, and minerals), and phytonutrient (e.g., polyphenolics and carotenoid) composition of dry edible beans, peas, lentils, and chickpeas. Soybean and peanuts will not be covered in this review. The effects of processing on composition will also be covered. The health benefits related to folates, fiber, and polyphenolics will be highlighted. The health benefits discussed will include cardiovascular disease, cancer, diabetes, and weight control. The current review will not cover antinutrient compounds; this topic will be covered in a separate review article published in the same issue.     

Dissipation of monosodium methane arsonate (MSMA) on peanuts

Monosodium methane arsonate (MSMA), the salt of methylarsonic acid (MAA), is a herbicide commonly used to control weeds along roadsides, in cotton, in turf, and on noncrop sites. In recent years questions have arisen regarding the source and nature of arsenic residues in raw agricultural commodities relative to misuse, inadvertent exposure, or rotational crop residues. Field experiments were conducted to determine the fate of MSMA that is applied to peanut foliage. Persistence, dissipation, recovery, and detection of MAA from leaf rinsate were characterized as well as resulting total arsenic and MAA concentrations in peanut kernels. MSMA was applied to peanut foliage at 105, 210, 315, and 420 g of active ingredient (ai)/ha. Peanut leaves were sampled before and after irrigation events over the next 7 days. Peanuts were harvested at maturity and analyzed for MAA and total arsenic. A confined rotational crop experiment was conducted to determine the potential for MAA residues in soil to be taken up by peanuts in fields rotated from cotton that was treated with MSMA. MAA was not detected in any peanut samples from the rotational crop experiment, even when peanuts were planted only 30 days after MSMA application to the soil at 2.24 kg of ai/ha. Field experiments showed that MSMA recovery from leaves with an aqueous rinse declined quickly but was not greatly affected by irrigation. However, quantifiable amounts of MAA were present 1 week after application and after two irrigation events, and MAA and total arsenic were measured in mature peanut kernels from all plots that received MSMA. MAA was not detected in untreated checks. Total arsenic was below the limit of quantification in untreated controls.     

种植至储藏期花生黄曲霉毒素B_1污染研究

为解析种植至储藏期花生受黄曲霉侵染及黄曲霉毒素B1(AFB_1)污染的规律,揭示花生AFB_1污染的源头及主要影响因素,选取种植湛红2号和湛油75的花生田,采集种植期花生果和土壤及储藏1~4个月的花生果,分析花生和土壤真菌菌相,并采用高效液相色谱法测定花生AFB_1含量。结果表明,种植期黄曲霉侵染花生果主要发生在成熟期,但黄曲霉污染率均在8%以下;湛油75花生田土壤黄曲霉菌落数显著低于湛红2号,但花生果黄曲霉污染率显著高于湛红2号,表明湛红2号具有一定的黄曲霉抗性;湛油75和湛红2号分别在110 d和120 d检测到AFB_1,含量分别为3.37μg·kg~(-1)和2.08μg·kg~(-1),表明花生黄曲霉毒素含量与污染率呈正相关。储藏期花生果中未检测到黄曲霉和AFB_1,这主要是由于花生晾晒后水活度(aw)降低至0.70以下,不适合黄曲霉生长繁殖和毒素生物合成。综上,黄曲霉在荚果成熟期开始侵染花生果导致产生AFB_1,而储藏期保持较低的aw可有效预防黄曲霉及AFB_1污染。本研究结果为制定种植至储藏期花生黄曲霉毒素全程防控措施提供了理论依据。     

Comparative characterization of peanuts grown by aquatic floating cultivation and field cultivation for seed and resveratrol production

Peanut pods (Tainan 12, a Spanish cultivar, Arachis hypogaea L.) have been obtained from peanuts grown in a newly developed aquatic floating cultivation system without artificial aeration or periodic renewal of the solution. The system provided a convenient status for examination of root and pod development. Compared to field-grown peanuts of the same cultivar, the aquatic-cultivated peanut pods and seeds were smaller, whereas seed/pod weight ratios, crude fat and protein contents, and SDS-PAGE protein patterns varied within similar ranges. During cultivation, the highest detected temperature of the aquatic solution was higher than the field-soil temperature. After gas chromatographic analysis of the fatty acid compositions, the oleic acid/linoleic acid ratio of the aquatic-cultivated seeds was higher than that of field-cultivated ones. When the peanut roots were collected, cleaned, dried, weighed, pulverized, and subjected to resveratrol analysis, dry root weights were 4.2 +/- 0.1 and 2.2 +/- 1.1 g/plant and resveratrol contents were 0.074 +/- 0.009 and 0.114 +/- 0.212 mg/g for the aquatic- and field-cultivated peanut roots, respectively. This indicates that the aquatic-cultivated peanut roots could be a potent and consistent source of resveratrol.     

Immature Compost Suppresses Weed Growth Under Greenhouse Conditions

The influence of immature municipal solid waste-biosolids composts on emergence and mean days to emergence (MDE) of several weed species was evaluated in a pot trial under greenhouse conditions. The experiment consisted of placing a 7.5 cm deep layer of three-day-old immature compost, a mature and stable compost, an artificial medium or control sand as a mulch on ivyleaf morning glory seeds. Immature three-day-old compost decreased percentage emergence, shoot and root dry weight, and increased MDE of ivyleaf morning glory. In an experiment with eight-week-old immature compost utilizing mulching depths of 2.5, 5, 7.5, 10 cm and the untreated control on seeds of three weed species, common purslane did not emerge under any of the immature compost treatments. The MDE of ivyleaf morning glory and barnyard grass increased linearly as immature compost depths increased. Next, eight economically important weed species were sown in pots with either mature or immature (eight-week-old) compost utilizing mulching depths of 2.5 and 10 cm, in addition to an untreated control. Control pots yielded higher percentages of emergence than compost treatments for all species evaluated. Common purslane, large crabgrass, pig-weed, Florida beggarweed, and dichondra did not emerge through a 10-cm deep layer of mature compost mulch, or 2.5 or 10 cm deep layer of immature mulch. Significant compost maturity/depth interactions were observed for percent emergence on common purslane, ground cherry, large crabgrass, Florida beggarweed, and ivyleaf morning glory. A thinner layer was required to suppress germination using immature eight-week-old compost as compared to mature and stable compost. Immature (three-day or eight-week-old) compost containing acetic acid concentrations of 2474 and 1776 mg.kg^?1 respectively reduced percentage emergence of several economically important weed species. These studies suggest that immature composts can be used to control weeds under conditions where spatial separation is maintained between the crop and the compost and phytotoxic fermentation products do not affect the health of the mulched plants and where odors associated with such partially stabilized products do not pose problems.     

Interrelationship of phytoalexin production and disease resistance in selected peanut genotypes

In peanuts, a mechanism of resistance to fungal infection is reportedly due to the synthesis of stilbene phytoalexins, which are antibiotic, low molecular weight metabolites. The phytoalexin-associated response of different peanut genotypes to exogenous invasion in the field has not been investigated and may be useful for breeding resistant peanut cultivars. Five peanut genotypes, Georgia Green, Tifton 8, C-99R, GK-7 High Oleic, and MARC I, which differ in resistance to major peanut diseases, were investigated for their ability to produce phytoalexins under field conditions in South Georgia in 2001 and 2002. Five known peanut phytoalexins, trans-resveratrol, trans-arachidin-1, trans-arachidin-2, trans-arachidin-3, and trans-3'-isopentadienyl-3,5,4'-trihydroxystilbene, were quantitated. The phytoalexins were measured in peanuts of different pod maturity (yellow, orange, brown, and black) with or without insect pod damage (externally scarified or penetrated). Kernels from insect-damaged pods of C-99R and Tifton 8 genotypes had significantly higher concentrations of phytoalexins than other genotypes. The same genotypes were the most resistant to tomato spotted wilt virus and late leaf spot, while MARC I, which is highly susceptible to these diseases, produced very low concentrations of phytoalexins. However, there was no significant difference in phytoalexin production by undamaged peanut pods of all tested genotypes. trans-Arachidin-3 and trans-resveratrol were the major phytoalexins produced by insect-damaged peanuts. In damaged seeds, the concentrations of trans-3'-isopentadienyl-3,5,4'-trihydroxystilbene were significantly higher in Tifton 8 as compared to other genotypes. There was an association between total phytoalexin production and published genotype resistance to major peanut diseases. Stilbene phytoalexins may be considered potential chemical markers in breeding programs for disease-resistant peanuts.     

Allergenic properties of roasted peanut allergens may be reduced by peroxidase

Peanut allergy is a public health issue. The culprits are the peanut allergens. Reducing the allergenic properties of these allergens or proteins will be beneficial to allergic individuals. In this study, the objective was to determine if peroxidase (POD), which catalyzes protein cross-linking, reduces the allergenic properties of peanut allergens. In the experiments, protein extracts from raw and roasted defatted peanut meals at pH 8 were incubated with and without POD in the presence of hydrogen peroxide at 37 degrees C for 60 min. The POD-treated and untreated samples were then analyzed by SDS-PAGE, western blots, and competitive inhibition ELISA. IgE binding or allergenicity was determined in blots and ELISA. Results showed that POD treatment had no effect on raw peanuts with respect to protein cross-linking. However, a significant decrease was seen in the levels of the major allergens, Ara h 1 and Ara h 2, in roasted peanuts after POD treatment. Also, polymers were formed. Despite this, a reduction in IgE binding was observed. It was concluded that POD induced the cross-linking of mainly Ara h 1 and Ara h 2 from roasted peanuts and that, due to POD treatment, IgE binding was reduced. The finding indicates that POD can help reduce the allergenic properties of roasted peanut allergens.     

气爆式花生脱壳性能的试验研究

利用花生壳本身的透气性,将花生果置于容器内,密封后充入较高压力的气体,维持一定时间,使花生壳内外压力在短时间内达到规定值,然后突然释放,实现了采用气爆原理使花生脱壳的性能试验。文中分析了影响气爆式脱壳的主要因素,找出了提高气爆式花生脱壳率的最佳充气压力和稳定压力维持的时间。     

花生种子自然老化对品质及发芽的影响

为解析花生种子自然老化过程中品质及发芽特性的变化特征,本研究以6个花生品种(系)为试材,通过测定种子发芽率、发芽势、氯化三苯基四氮唑(TTC)还原量、电导率等指标对老化花生种子的品质和发芽活力进行综合评价.结果表明,随着种子老化程度加深,不同品种(系)花生种子的5个发芽指标(发芽率、发芽势、发芽指数、活力指数和生长量)...     

Food grade fungal stress on germinating peanut seeds induced phytoalexins and enhanced polyphenolic antioxidants

The effects of food grade fungus Rhizopus oligosporus stress on phytochemicals and phytoalexins of germinating peanut seeds were investigated by comparing the metabolic profiles of ungerminated (UG), germinated (G), and germinated seeds under fungal stress (GS). Three types of peanut seeds with different skin color (red, reddish brown, and black) were compared in the process. The polyphenolic contents were analyzed and correlated with antioxidant capacity for specific free radicals including peroxyl radical ROO(?) (ORAC), hydroxyl radical HO(?) (HORAC), superoxide radical O(2)(?-) (SORAC), and DPPH radical. The polyphenolic fingerprints analyzed by HPLC and LC-MS(n) showed that phenolic acids (coumaric, sinapinic, and ferulic acids derivatives) were the major group of phenolic compounds in ungerminated seeds. G or GS increased the level of phenolic acids, phytoalexins, and antioxidant capacity values in reddish and red peanuts but not in black peanuts. From the LC-MS(n) spectral data, 45 compounds were identified tentatively in the germinated peanuts, including 14 coumaric acids, 3 ferulic acids, 4 sinapinic acids, 2 hydroxybenzoic acids, 1 caffeic acid, 2 flavonoids, and 19 stilbenoids derivatives. Reddish brown germinated peanuts produced the highest amount of phytoalexins after GS with 55 compounds detected. Forty-five of these compounds were suggested as stilbenoid phytoalexins derivatives. The high content of phytoalexins may enhance the bioactivity of peanut seeds as functional food ingredients.     

Elicitation of resveratrol in peanut kernels by application of abiotic stresses

Application of no postharvest stress or by size reduction, grinding, chopping, or slicing and exposure to UV light or ultrasound were investigated for the elicitation of trans-resveratrol, total phenolic compounds, and antioxidant activity (AOA) in peanut kernels. AOA and total phenolic compounds did not increase in stressed peanuts over incubation times 0-48 h at 25 degrees C; however, an increase in trans-resveratrol concentration over time occurred. Slicing (2 mm), ultrasound exposure for 4 min at 25 degrees C, and incubation for 36 h produced the highest level of trans-resveratrol synthesis in peanuts, increasing concentrations from 0.48 +/- 0.08 microg/g in untreated peanuts to 3.96 +/- 0.96 microg/g. AOA in stressed peanuts was negatively correlated with trans-resveratrol concentration, indicating that as AOA decreased trans-resveratrol concentration increased.     

Influence of thermal processing on the allergenicity of peanut proteins

Peanuts are one of the most common and severe food allergens. Nevertheless, the occurrence of peanut allergy varies between countries and depends on both the exposure and the way peanuts are consumed. Processing is known to influence the allergenicity of peanut proteins. The aim of this study was to assess the effect of thermal processing on the IgE-binding capacity of whole peanut protein extracts and of the major peanut allergens Ara h 1 and Ara h 2. Whole proteins, Ara h 1, and Ara h 2 were extracted and purified from raw, roasted and boiled peanuts using selective precipitation and multiple chromatographic steps, and were then characterized by electrophoresis and mass spectrometry. The immunoreactivity of whole peanut extracts and purified proteins was analyzed by the enzyme allergosorbent test (EAST) and EAST inhibition using the sera of 37 peanut-allergic patients. The composition of the whole protein extracts was modified after heat processing, especially after boiling. The electrophoretic pattern showed protein bands of low molecular weight that were less marked in boiled than in raw and roasted peanuts. The same low-molecular-weight proteins were found in the cooking water of peanuts. Whole peanut protein extracts obtained after the different processes were all recognized by the IgE of the 37 patients. The IgE-binding capacity of the whole peanut protein extracts prepared from boiled peanuts was 2-fold lower than that of the extracts prepared from raw and roasted peanuts. No significant difference was observed between protein extracts from raw and roasted peanuts. It is noteworthy that the proteins present in the cooking water were also recognized by the IgE of peanut-allergic patients. IgE immunoreactivity of purified Ara h 1 and Ara h 2 prepared from roasted peanuts was higher than that of their counterparts prepared from raw and boiled peanuts. The IgE-binding capacity of purified Ara h 1 and Ara h 2 was altered by heat treatment and in particular was increased by roasting. However, no significant difference in IgE immunoreactivity was observed between whole protein extracts from raw and roasted peanuts. The decrease in allergenicity of boiled peanuts results mainly from a transfer of low-molecular-weight allergens into the water during cooking.     

一种发根农杆菌介导的花生遗传转化新方法

花生是中国重要的油料作物、经济作物和豆科作物。作为世界第一花生生产国和出口国,利用遗传转化方法,加快花生生物性状和遗传育种的研究势在必行。花生根系和根瘤系统的研究对于提高花生抗性进而提高花生的产量和品质以及生物固氮能力具有重要的意义。然而,目前花生遗传转化体系还不成熟,给花生研究造成了严重的障碍。本文建立了利用发根农杆菌介导花生下胚轴形成转基因毛根和根瘤的新方法,并分别用GFP和GUS两种检测方法对该转化体系进行了检测,表明该方法是一个操作简易、高效的遗传转化方法,为利用基因工程技术对花生进行研究和遗传改良提供了一套新方法。     

基于水培生菜力学特征的成熟度分类方法

为了能准确识别生菜的成熟度,实现生菜适时采收,避免因采收期不当而造成品质下降等问题,该研究提出用穿刺试验力学特征表征水培生菜成熟度的方法,提取同一颗生菜不同叶片的不同部位时域和频域的力学特征,得到叶片力学特征与叶片成熟特性指标的相关性。为了对水培生菜未成熟株、成熟株、过成熟株进行准确分类,设计双阈值深度遍历算法,确定分类准确率最高的叶片类型和区域;采用6种机器学习算法以该区域所有的力学特征为输入,以成熟度3种分类为输出进行训练。试验结果表明,生菜叶片力学特征与成熟度特性指标紧密相关,生菜中叶叶茎区域分类准确率最高,可优化集成分类机器学习算法准确率最高为94.3%。研究结果提供了一种应用力学特征解决水培生菜成熟度检测与分类的新方法。     

Indirect competitive ELISA for determination of traces of peanut (Arachis hypogaea L.) protein in complex food matrices

An indirect competitive ELISA was developed allowing the detection of hidden peanut protein residues down to 2 ppm (micorgrams per gram) in various foods. The high-titer, peanut-specific polyclonal antiserum used recognized potentially allergenic proteins in both native and roasted peanuts. In the absence of a food matrix, extractable protein from roasted peanuts was detected at 104 +/- 13%. From various food items, peanut protein at > or =13 ppm was recovered between 84 and 126%, and at 2 ppm of peanut protein recovery was 143 +/- 6%. Intra- and interassay precision was <15%. In 5 of 17 commercial food products without declaration of peanut components, between 2 and 18 ppm of peanut protein was detected. This is the first assay based on commercially available reactants that allows the reliable determination of trace amounts of hidden peanut allergens in a variety of complex food matrices.     

莲子间歇式微波分段变功率真空干燥方法

目前莲子干燥仍以传统热风干燥为主,该方式不仅能耗高,耗时长,且莲子品质不佳,严重制约了莲子产业的高质量发展。为了提高莲子干燥品质、缩短干燥时间和降低能耗,该研究比较了间歇式微波恒定功率和微波分段变功率两种微波真空干燥法,分析了微波功率、干燥时间对莲子干燥特性影响。研究结果表明,间歇式微波分段变功率真空干燥较佳工艺参数为:真空度0.1 MPa,微波工作间歇方式为1.5 min-开/1.5 min-关,干燥过程分两个阶段进行,第一阶段在微波功率1 600 W条件下共工作3 min,间歇3 min,第二阶段在微波功率1 200 W条件下共工作3 min,间歇3 min。在此条件下,莲子主要营养成分中淀粉含量43.43 g/100 g,与恒定微波功率真空干燥(40.83～43.80 g/100 g)和传统热风干燥(42.73g/100 g)效果相当;蛋白质含量为19.37 g/100g,高于恒定微波功率真空干燥(18.17～18.67g/100 g)与热风干燥(18.57 g/100 g);膳食纤维含量为14.60 g/100 g,是热风干燥(6.94 g/100 g)的2.10倍,具有显著性差异(P0.05),与恒定微波功率真空干燥(11.03～14.70 g/100 g)无明显差异(P0.05);单位质量干燥能耗为7 848 kJ/kg,相较于传统热风干燥(465 012 kJ/kg)和恒定微波功率真空干燥(10 440～15 012 kJ/kg),干燥时间缩短,能耗降低。研究结果为莲子的加工生产提供理论支持。