Compositional analysis and roasting behaviour of gevuina and macadamia nuts

This study compares the composition of macadamia and gevuina nuts following natural abscission and air-drying of intact nuts and compares chemical and sensory properties on roasting gevuina nuts using a reported macadamia roasting process. The markedly higher fat content of macadamia (75% vs. 43%) reflected a higher percentage of protein, moisture, ash and carbohydrate in gevuina nuts. Gevuina nuts also had lower energy and pH values than macadamia. Water activities were similar. Both oils were around 80% monounsaturated, but differed widely in positional isomerism. On roasting, macadamia nuts developed sweet, nutty, buttery notes along with brown colour development (measured using L *, a *, b * values) after 20 min at 135 °C while gevuina nut colour and aroma took at least 30 min, where the aroma was more hazelnut-like. Extractable volatiles were significantly higher for macadamias following roasting.     

澳洲坚果仁营养成分分析与其加工副产物的综合利用研究

澳洲坚果香脆可口,营养丰富,富含多种人体生长所必需的营养物质,同时我国的澳洲坚果种植面积广。因此,该文重点对澳洲坚果仁的营养成分进行分析,并对澳洲坚果仁的加工副产物,包括澳洲坚果壳、澳洲坚果青皮以及澳洲坚果粕的综合利用进行综述,以期为澳洲坚果的市场化开发和综合利用提供理论参考。     

Quality Evaluation of Shelled and Unshelled Macadamia Nuts by Means of Near‐Infrared Spectroscopy (NIR)

The quality of shelled and unshelled macadamia nuts was assessed by means of Fourier transformed near‐infrared (FT‐NIR) spectroscopy. Shelled macadamia nuts were sorted as sound nuts; nuts infected by Ecdytolopha aurantiana and Leucopteara coffeella; and cracked nuts caused by germination. Unshelled nuts were sorted as intact nuts (<10% half nuts, 2014); half nuts (March, 2013; November, 2013); and crushed nuts (2014). Peroxide value (PV) and acidity index (AI) were determined according to AOAC. PCA‐LDA shelled macadamia nuts classification resulted in 93.2% accurate classification. PLS PV prediction model resulted in a square error of prediction (SEP) of 3.45 meq/kg, and a prediction coefficient determination value (R_p²) of 0.72. The AI PLS prediction model was better (SEP = 0.14%, R_p² = 0.80). Although adequate classification was possible (93.2%), shelled nuts must not contain live insects, therefore the classification accuracy was not satisfactory. FT‐NIR spectroscopy can be successfully used to predict PV and AI in unshelled macadamia nuts, though.     

广西澳洲坚果果实品质分析与综合评价

为探明广西澳洲坚果果实主要品质特征,建立果实经济性状综合评价方法。对14?个广西主产地澳洲坚果果实优果判别指标以及果仁脂肪酸、氨基酸、矿质元素组成与含量等品质指标进行测定,运用因子分析、聚类分析和正交偏最小二乘判别分析对其品质进行综合评价。结果表明：广西不同产地澳洲坚果果实品质存在明显差异,42.9%的果园好果率低于97%,需要加强果园管理工作。广西澳洲坚果果仁中不饱和脂肪以油酸、棕榈油酸为主,水解氨基酸以药效氨基酸为主,磷、钙含量相对其他矿物质元素含量较多。系统聚类分析显示广西澳洲坚果可以分为3?类,好果率、脂肪、蛋白质、棕榈酸、十七烷酸、硬脂酸、花生酸、油酸、亚麻酸、二十碳三烯酸、天冬氨酸、苏氨酸、丝氨酸、谷氨酸、丙氨酸、缬氨酸、异亮氨酸、亮氨酸、酪氨酸、苯丙氨酸、赖氨酸、磷22?个指标是不同产地澳洲坚果样品间的差异指标。利用因子分析法建立澳洲坚果经济性状评价模型,逐步回归分析验证模型具有非常高的预测准确性;第3类（12、14号）品质相对最优,第1类（1、2、3、6、7、8、9、10、11、13号）次之,第2类（4、5号）再次之。该研究为准确了解广西澳洲坚果果实品质、品质评价标准建立及品质调控提供参考和依据。     

A novel real-time polymerase chain reaction method for the detection of macadamia nuts in food

A real-time PCR-based method for the detection of macadamia nuts (fruits of Macadamia integrifolia or M. tetraphylla or their hybrids) in food products is described. The method consists of DNA isolation by chaotropic solid phase extraction and subsequent PCR with macadamia-specific primers and a TaqMan fluorescent probe. The primers and the probe were targeted to the gene encoding for vicilin precursor. The method was positive for M. integrifolia and M. tetraphylla and negative for 16 other plant species used in food industry, including peanuts, walnuts, hazelnuts, almonds, pistachio nuts, cashew nuts, Brazil nuts, and chestnuts. The DNA-based detection limit of the method was 1.45 pg. Using a series of model samples with defined macadamia nut contents, a practical detection limit of 0.02% (w/w) macadamia nuts was determined. Practical applicability of the PCR method was tested by the analysis of 14 confectionery samples. For all of the samples, results conforming to the labeling were obtained. The presented PCR method is useful for relatively fast, highly selective, and moderately sensitive detection of macadamia nuts in food samples.     

Functional lipid characteristics,oxidative stability,and antioxidant activity of macadamia nut (Macadamiaintegrifolia) cultivars

Phytochemical compounds (tocopherols, tocotrienols, and squalene) were measured in seven macadamia cultivars harvested from four locations on Hawaii island to establish whether these compounds enhance the oxidative stability of roasted kernels. Cultivars that had the greatest oxidative stability also had high total lipid-soluble antioxidant capacity. Tocopherols [delta (δ), gamma (γ), alpha (α)] were not detected in most macadamia nut samples, but macadamia kernels contained significant amounts of tocotrienols (31–92 μg/g oil) and squalene (72–171 μg/g oil) for all cultivars tested. This is the first report of variation for three tocotrienol homologs (δ-, γ-, α-T3) and total antioxidant capacity in macadamia nut cultivars. No statistical correlations were found between oxidative stability and tocopherol, tocotrienol, and squalene concentrations. However, two cultivars (HAES 294 and HAES 835) were identified with superior oxidative stability, suggesting that the kernel quality of these cultivars is more stable during storage.     

Temperature- and Moisture-Dependent Dielectric Properties of Macadamia Nut Kernels

Conventional hot air drying for macadamia nuts takes several weeks, generating great interest in developing advanced drying technologies. Radio frequency (RF) and microwave (MW) heating hold potential for providing fast and uniform drying with acceptable product quality. To clearly understand the interaction between electromagnetic energy and macadamia nuts, information on dielectric properties of the kernels is needed for designing a practical and effective drying process. In this study, dielectric properties of the macadamia nut kernels were measured between 10 and 1,800 MHz using an open-ended coaxial-line probe technique at temperatures between 25 and 100 °C and moisture contents between 3 % and 24 % on a wet basis (w.b.). The results showed that both dielectric constant and loss factor of the kernels decreased sharply with increasing frequency over the RF range (10 to 300 MHz), but gradually over the measured MW range (300–1,800 MHz), which were largely enhanced by increasing moisture content and temperature. Penetration depth decreased with increasing frequency, moisture content, and temperature. Based on this study, uniform drying of macadamia nut kernels in thick layers could be effectively developed using RF energy.     

制油工艺对澳洲坚果油营养品质及挥发性风味成分的影响

研究压榨法和水剂法2种制油工艺对澳洲坚果油品质及挥发性风味成分的影响,分别比较2种制油工艺对澳洲坚果油甘油三酯组成、甾醇组成、脂肪酸组成、挥发性风味成分、生育酚及矿质元素含量的影响。结果表明:制油工艺对澳洲坚果油的脂肪酸组成、甘油三酯组成和生育酚含量没有显著影响,澳洲坚果油中脂肪酸主要为油酸、棕榈-烯酸、棕榈酸,占86%以上;甘油三酯共检出18种,其中OOO、POS、POO占53%以上;水剂法制得的澳洲坚果油中甾醇含量较高,为1 439.79 mg/kg;压榨法制得的澳洲坚果油中矿质元素含量较高,挥发性风味物质成分较多,共分离出41种,主要包括烯类、醛类、酚类、醇类、酯类、烃类和酮类共7类化合物,其中相对含量较高的是烯类化合物和醇类化合物,占总挥发性成分的82.1%,是构成压榨澳洲坚果油的主要风味物质。     

Multivariate Classification of UHT Milk as to the Presence of Lactose Using Benchtop and Portable NIR Spectrometers

Lactose hydrolyzed milk was developed in the 1970s to serve individuals with lactose intolerance. This demand for lactose-free products by lactose-intolerant consumers has created a market segment for this food whose quality control has to be guaranteed. In order to assess milk samples for lactose content, this work proposes an analytical methodology to classify regular and lactose-free ultra high temperature (UHT) milks using multivariate classification methods and NIR spectra obtained in FT-NIR and ultra-compact NIR spectrometers, aiming at field analysis. For this, 71 samples were purchased; 41 were lactose-free UHT milk and 30 regular UHT milk. Diffuse transflectance spectra were obtained by FT-NIR (833 to 2500 nm, 4 cm^?1 of resolution and mean of 16 scans), and by ultra-compact NIR (908 to 1676 nm, with 12.5 nm of resolution and mean of 50 scans). The classification models were obtained by PLS-DA and LDA techniques with robust variables selection by SPA and GA, evaluating different spectral pre-processing (MSC, SNV, and derivatives). The three models developed (PLS-DA, GA-LDA, and SPA-LDA) with benchtop equipment spectra correctly classified all samples with sensitivity and specificity of 100%. For the portable equipment spectra, PLS-DA and GA-LDA models obtained sensitivity and specificity of 100%. The SPA-LDA model, however, presented sensitivity and specificity of 80 and 100%, respectively. These results indicate that methodologies using NIR equipment, especially the ultra-compact NIR, with multivariate classification techniques are feasible in discrimination between regular and lactose-free milk in the field, thus enabling a quick and precise analysis.     

Image-Based Screening for the Identification of Bright Greenish Yellow Fluorescence on Pistachio Nuts and Cashews

The development of screening methodologies for a rapid identification of crops contaminated with aflatoxin is of great interest to agro-food industry. The objective of this work was to develop an image algorithm able to identify bright greenish yellow fluorescence (BGYF) on pistachio nuts and cashews. Previous researchers established that the presence of BGYF indicates that there is a high probability of aflatoxin contamination. Since BGYF is not a definitive indicator of aflatoxin contamination, samples emitting fluorescence should be removed and tested for aflatoxins by chemical means. This study, conducted in a static way, is an important step towards the development of a new more accurate and automatic aflatoxin screening method based on a vision system. In this work, a total of 352 samples of pistachio nuts and cashews were evaluated, half of which came from lots contaminated with aflatoxin. Two images in the 410–600 nm optical range were acquired for each sample. Imaging algorithms were developed to identify samples with fluorescent stains caused by BGYF. According to the image analysis results, nut samples were classified into two groups: fluorescent stains (FS) and non-fluorescent stains. Both BGYF and non-fluorescent samples were analyzed for aflatoxin. The laboratory analysis results showed a high correlation with the camera classification: pistachios and cashews placed in the FS group by the vision system contained 92 % and 82 % of the total number of nuts contaminated with aflatoxin, respectively. Moreover, a discriminant analysis of reflectance data was carried out in order to select the optimal optical range to detect BGYF, both in pistachio nuts, i.e., 480 and 520 nm, and in cashews, i.e., 440 and 600 nm.     

Non-destructive prediction of hardening pericarp disorder in intact mangosteen by near infrared transmittance spectroscopy

A non-destructive technique to predict a hardening pericarp disorder in intact mangosteen is proposed by using near infrared (NIR) transmittance spectroscopy in the wavelength range of 660-960 nm. The study found that the spectral features of normal pericarp mangosteen and hardening pericarp mangosteen were different. The averaged spectra and individual spectra of hardening pericarp mangosteen from a calibration set (N = 560) were used to develop classification models, using partial least squares discriminant analysis (PLS-DA). A model based on individual spectra obtained better classification. The overall accuracy of classification for a prediction set (N = 358) was 91%. Out of 179 samples of normal pericarp fruits, 167 were identified correctly, while 159 samples out of 179 samples with hard pericarp were predicted correctly. The results showed that NIR transmittance spectroscopy can be used to predict hard pericarp disorder in intact mangosteen fruit accurately.     

苹果品种及损伤苹果的FT-NIR鉴别研究

用傅里叶近红外光谱技术(FT-NIR)对不同品种的苹果以及损伤嘎啦和完好嘎啦进行快速、无损检测,比较不同判别方法对所建立的区分苹果品种及苹果损伤模型的影响。结果表明:损伤嘎啦和完好嘎啦的近红外图谱经小波分析预处理后,用12000～4000cm-1波数范围的前5个主成分分别结合多层感知神经网络、径向基神经网络、Fisher判别3种方法所建立的判别模型对未知样本的正确判别率分别为97.8%、87.2%和84.8%,基于权重法用多元线性回归(MLR)所选择的特征波长所建立的Fisher判别模型对未知样本的正确判别率为89.1%;用偏最小二乘判别(PLS-DA)所建立的判别模型对未知样本的正确判别率为100%,由于PLS-DA模型对训练集和验证集的正确判别率均为100%,因此PLS-DA模型优于其他模型。不同品种苹果的光谱经平滑预处理后,用全波数范围12000～4000cm-1的前6个主成分所建立的判别模型优于经验波数范围8000～4500cm-1所建立的判别模型,其较优模型对建模集和验证集的正确判别率分别为90.9%和92.1%。近红外光谱技术结合化学计量学可以快速、无损鉴别苹果是否有损伤以及不同品种的苹果。     

澳洲坚果各部位蜀黍苷含量的测定

为检测澳洲坚果果仁、花、叶、壳和青皮各部位的蜀黍苷含量,并为澳洲坚果各部位的开发利用提供依据,以苦杏仁苷为内标物质,采用高效液相色谱法,Diamonsil C₁₈(150 mm×4.6 mm,5 μm)色谱柱,柱温35℃,自动进样器进样量5 μL,总流速1.0 mL/min,乙腈(A)-0.1%甲酸水溶液(B)为流动相,使用蒸发光散射检测器(ELSD)进行检测。结果表明:蜀黍苷和苦杏仁苷标准品的浓度比(X)与对应的峰面积比(Y)所作标准曲线方程为Y=0.465389X2+0.349685X-0.000520968,决定系数R2=0.9977,RSD为2.60%。方法的平均回收率为97.93%±2.35%,RSD为2.39%。对澳洲坚果各部位蜀黍苷含量进行测定发现,澳洲坚果花中蜀黍苷含量最高,达(49.92±0.96)mg/g,叶次之,果仁中蜀黍苷含量最低,仅为(0.64±0.01)mg/g。且不同品种青皮中蜀黍苷含量亦不同。HPLC-ELSD内标法测定蜀黍苷快速简便,准确度高,重复性好,成本较低,测定结果可靠。澳洲坚果花、叶中蜀黍苷含量较高,使用时应适当考虑脱除其中的蜀黍苷。澳洲坚果仁中仅含微量蜀黍苷,在安全使用范围之内。     

Carbohydrate composition and color development during drying and roasting of macadamia nuts (Macadamia integrifolia)

Research was conducted to determine whether variability in sugar content contributes to differences in kernel browning during processing of macadamia nut (Macadamia integrifolia) cultivars, Kau (HAES 344), Keaau (HAES 660), Keauhou (HAES 246), and Kakea (HAES 508). At harvest, total sugar content of fresh macadamia kernels varied from 2.9 to 5.6 g/100 g dry weight basis (db), and the average moisture content ranged from 15.6 to 23.6 g/100 g fresh weight. Cultivars differed in kernel sucrose content, but not reducing sugar content. Reducing sugars decreased during drying, and kernel centers darkened slightly. An incremental drying process limited sucrose hydrolysis, minimizing the amount of glucose and fructose available for browning reactions. Therefore, the centers of roasted kernels were not darker than dried kernels. The variability in sugar composition in fresh kernels had a minimal impact on color quality when low-temperature drying and roasting at 125 °C were used. However, when roasted kernels received from a processor were separated based on color quality, kernels with internal or external browning had higher reducing sugar concentrations (0.24-0.27 g/100 g db) than cream-colored kernels (0.03 g/100 g db). Immature kernels had higher sucrose and reducing sugar contents and more browning than mature kernels. During commercial processing, optimal conditions may not be achieved and the presence of immature nuts can contribute to kernel browning.     

基于改进型YOLO的密集环境下槟榔果实的快速识别方法

目的:提高小个体槟榔的识别精确率以及槟榔加工厂的自动化程度。方法:设计并选取Mob-darknet-52作为新型特征提取网络,采用多尺度检测尺寸,提出一种基于改进型YOLO算法的槟榔定位与识别的方法。结果:Mob-YOLOV3-SPP对槟榔果实分类的检测精度为94.8%,准确率为94.5%,召回率为95.1%,模型的检测时间为6.679 ms。结论:基于改进型YOLOV3网络的优化算法可以实现密集环境下槟榔果实的快速定位与识别。     

Nut and kernel traits and chemical composition of hazelnut (Corylus avellana L.) cultivars

BACKGROUND: Nut and kernel traits and chemical composition of 24 Italian and foreign hazelnut cultivars were analysed in 2002–2004 in order to study the effect of genotype and environment on nut quality. Nuts were sampled in a germplasm collection in the Italian province of Viterbo. RESULTS: Quantitative and qualitative determinations of sugars, organic acids and lipids revealed good nutritional and health potential of the nuts, with several differences among cultivars and years. The total contents of oil and sugars ranged from 563.69 to 656.36 g kg^?1 dry weight (DW) and from 39.80 to 59.51 g kg^?1 DW respectively. Fatty acid profile and sugar and total phenolic contents varied with the year. Significantly higher palmitic acid concentration (6.18%) was found in the hot summer year 2003; lower saturated fatty acid concentration (8.20%) and higher unsaturated/saturated acid ratio (11.27) were observed in the coolest year (2004). These differences among years were highlighted by discriminant analysis. CONCLUSION: The information relating to secondary components such as sugars, organic acids and phenolics was useful for discriminating among cultivars and years. Owing to the effect of these compounds on sensory attributes perceived by consumers, their concentration and the varietal differences can be considered primary determinants of nut quality and should be valued when planning the cultivar choice for new plantations. Copyright © 2008 Society of Chemical Industry     

Pistachio nut allergy: An updated overview

Pistachio nut (Pistacia vera) is highly appreciated for its organoleptic characteristics and potential health benefits. However, this tree nut is also responsible for triggering moderate to severe IgE-mediated reactions in allergic individuals. Currently, pistachio nut allergy has gained some special attention, mainly due to its intrinsic relation with cashew nut allergy. Like for other nuts, the prevalence of pistachio nut allergy seems to be increasing at a global scale. Until now, there are five allergenic proteins officially listed for pistachio nut (Pis v 1, Pis v 2, Pis v 3, Pis v 4 and Pis v 5). Relevant data on their biochemical classification has become available, enabling establishing a correlation with the respective clinical symptoms. The establishment of an effective allergen risk assessment is a key issue for the food industry, policy makers and regulatory agencies. Thus, the availability of fast, specific and sensitive methods to detect trace amounts of allergens in processed foods is crucial. In the specific case of pistachio nut, there are some protein- and DNA-based methods for its detection/quantification in foods, which can aid to verify label information. Accordingly, all relevant research advances on this topic were summarised, updated and critically discussed in this review.     

坚果的主要生物活性成分及其保健作用

坚果作为高档零食,其营养价值和保健功能也越来越受到人们的关注?本论文综述了常见坚果(如澳洲坚果、核桃、榛子、杏仁、松子、板栗、山核桃、开心果,日本核桃、巴西坚果、花生等)中的酚类(原花青素、酚酸、黄酮、单宁、烷基酚、维生素E等)?酸类?甾醇类、色素(类胡萝卜素、叶绿素等)、硒、糖苷、功能性脂肪酸等营养物质和生物活性成分,并阐述了食用坚果与预防心血管疾病?延年益寿?预防糖尿病?控制体重等保健作用的关系?这对于进一步研究坚果与健康的关系、正确挑选与消费坚果均具有较好的指导意义。     

澳洲坚果片加工工艺与技术研究

以澳洲坚果粕粉为主要原料,辅以奶粉、白砂糖等配料,经混合、制软材、造粒、干燥与压片等工序,制成营养丰富,咀嚼感良好,硬度适中,易崩解,具有澳洲坚果香味、奶味及甜味的澳洲坚果片。通过单因素试验与正交试验确定了澳洲坚果片的最佳配方:麦芽糊精、β-环糊精、澳洲坚果粉、奶粉、白砂糖的配比为5∶5∶20∶20∶6,硬质酸镁的添加量1.2%。     

坚果中主要过敏原种类、检测及脱敏技术研究进展

近年来由于摄入坚果而导致的过敏反应屡见报道,已成为影响和威胁人体健康的一类重要的食品安全问题。本文对坚果中常见的过敏原的性质及危害进行了介绍,列举了目前国内外用于坚果过敏原检测的主要技术、特点及其应用,对比分析了不同处理方式对坚果中过敏原脱敏效果以及优缺点,指出目前坚果中过敏原检测及脱敏技术的不足和今后发展展望,旨在为坚果的加工和消费提供理论基础,助推坚果产业发展。