澳洲坚果仁的化学组成与其主要部分的利用

综述澳洲坚果仁及其油和油粕的主要化学成分与应用,为澳洲坚果的开发利用提供科学依据。     

澳洲坚果油和果仁的脂肪酸测定

使用KOH-甲醇法对澳洲坚果油和澳洲坚果仁进行甲酯化,采用GC-MS法测定脂肪成分,根据标准品保留时间定性,外标法定量。结果表明:KOH-甲醇法直接甲酯化能够测得澳洲坚果油中多种脂肪酸,相较于其他甲酯化方法含量上存在一定差异。     

澳洲坚果牛轧糖的制作工艺

为探索澳洲坚果牛轧糖的制作工艺,以澳洲坚果仁、黄油、棉花糖、奶粉为试验材料,采用单因素试验和正交试验,以感官评价作为参考指标,确定澳洲坚果牛轧糖的最佳制作工艺条件参数:糖油成分比例1︰4︰3,澳洲坚果仁添加量50%,熬糖温度140℃,熬糖时间3 min。在此条件下制得的牛轧糖感官评分达84.2分,成品色泽光亮、甜度适宜、口感软糯且细腻、咀嚼性好且不粘牙,兼具澳洲坚果和牛轧糖奶香味,并且富含澳洲坚果中多种有效成分,为提升澳洲坚果附加值提供科学基础,也为澳洲坚果新产品及功能性产品的研发和工业化生产提供理论参考。     

基于电子感官技术结合GC-MS分析不同干燥方式下澳洲坚果风味的差异

为科学评价不同干燥方式下澳洲坚果风味的差异,采用电子舌、电子鼻电子感官技术结合气相色谱-质谱（gas chromatography-mass spectrometry,GC-MS）对其风味品质进行分析。结果表明：不同干燥处理的果仁与新鲜果仁在鲜味、咸味、酸味和苦味上差异显著,且判别函数分析（linear discriminant analysis,LDA）前两主成分的累计贡献率为96.60%,可以完全区分不同方式干燥的澳洲坚果仁。电子鼻对不同处理的澳洲坚果仁有明显不同响应,主成分分析（principal component analysis,PCA）前两主成分的累计贡献率达到98.79%,可以很好地区分不同干燥处理的澳洲坚果果仁的挥发性风味物质,传感器W1S、W3S和W3C在主成分分析时发挥主要区分作用,GC-MS作为电子鼻的补充,共鉴定出227种挥发性成分,烷烃和醛类在种类与含量上占较大优势,四种不同处理的澳洲坚果仁的烷烃相对含量分别为26.29%、40.76%、23.64%及39.46%,醛类相对含量分别为29.01%、18.96%、26.03%及23.87%。可见,通过电子舌、电子鼻和GC-MS相结合的手段,可以较好地区分不同干燥方式下的澳洲坚果,从而为澳洲坚果的采后产地初加工提供理论参考。     

澳洲坚果酸奶的研制

该研究以澳洲坚果仁浆为主要原料开发一款澳洲坚果酸奶,通过单因素结合响应面优化试验,研究蔗糖添加量、发酵温度、发酵时间等因素对产品感官、酸度的影响,确定最佳工艺。结果表明：澳洲坚果酸奶最佳发酵菌种为保加利亚乳杆菌与嗜热链球菌复配,复配比例1:2（0.33%:0.67%）,感官评分可达85.5分,口感最佳;澳洲坚果仁料液比为1:3、热处理温度为65~75 ℃、采用二次均质（第一次为20 MPa均质5 min,第二次40 MPa均质10 min）、最佳发酵温度41.5 ℃、发酵时间7.5 h、蔗糖添加量6.27%,此条件下,其硬度为323.10 g,黏度53.04 mPa?s、持水性1.53%、pH值3.91,酸度76.12 °T,其蛋白质含量4.98%、脂肪含量11.80%,乳酸菌活菌数为1.65×109 CFU/g、大肠菌群、菌落总数、霉菌、酵母及致病菌（金黄色葡萄球菌、大肠杆菌、沙门氏菌）未检出。澳洲坚果酸奶含有15种脂肪酸,主要为不饱和脂肪酸（含量67.77%）。研发的澳洲坚果酸奶味道醇香、酸甜适中、口感细腻、质地均匀,是一款高蛋白、风味佳的纯植物基酸奶,在一定程度上丰富了酸奶品类,提升了澳洲坚果精深加工水平,对澳洲坚果产业健康发展具有积极的推动作用。     

水剂法提取澳洲坚果油的化学成分及其抗氧化活性研究

采用水剂法从烘干的澳洲坚果仁中提取仁油,先对其基本理化性质进行分析,再通过红外、气相和液相色谱法对坚果油的红外特性、脂肪酸组成、生育酚、磷脂、甾醇进行分析,并通过测定其氧化诱导时间和清除DPPH自由基的能力来综合评价澳洲坚果油的抗氧化能力。结果表明:水剂法提取的澳洲坚果油的过氧化值、酸价、碘值、皂化值、折光率、水分及挥发物含量分别为0.59 mmoL/kg、0.28 mg KOH/g、74.21g/100g、198.78mg KOH/g、1.466 8、0.36%;红外谱图显示澳洲坚果油具有坚果油的特征吸收;脂肪酸分析发现其不饱和脂肪酸含量为83.45%,其中棕榈油酸和油酸含量分别为17.25%和61.44%;甾醇含量为55.51 mg/100g;总酚酸含量为31.87 mg/100g;磷脂和生育酚均未检出;澳洲坚果油的氧化诱导时间为11.44h,其清除DPPH自由基的能力达89.84%,具有良好的抗氧化能力。     

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。     

澳洲坚果的营养价值及其开发利用

澳洲坚果是名贵的坚果，营养丰富而味美。本文简要介绍了澳洲坚果的营养价值、保健功能、药用价值、澳洲坚果的加工及制品以及发展澳洲坚果的经济意义。开发利用澳洲坚果资源，对丰富人们的饮食和保健，提高澳洲坚果的附加值有着重要的意义。     

澳洲坚果应用ASLT法预测食品保质期

澳洲坚果素有“干果皇后”之称,其含有丰富的油脂及不饱和脂肪酸,储存时易氧化变质,温度、湿度、氧含量等因素都对保质期有影响,应用ASLT法可对澳洲坚果的保质期进行预测。本文对澳洲坚果应用ALST法预测保质期的原理进行简要阐述,并以Q₁₀法(阿伦尼乌斯模型)测试奶香味澳洲坚果的保质期。     

不同干燥方式对澳洲坚果品质的影响

以适时采摘的澳洲坚果为原料,探讨自然晾晒、热泵干燥、热风干燥以及超声协同热风干燥4 种干燥方式对澳洲坚果果仁品质（水分含量、色泽、质地、酸价、过氧化值和不饱和脂肪酸含量）的影响。结果表明：热泵干燥得到的澳洲坚果果仁水分含量最低,硬度与酸价最小,油酸和棕榈油酸含量最高,果仁脆度最大;但自然晾晒对澳洲坚果果仁的色泽影响最小,且超声协同热风干燥和自然晾晒对澳洲坚果果仁的过氧化值影响最小。综合分析,热泵干燥效果最优,其不仅能提升干燥效率还能较好地保持澳洲坚果品质。     

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。     

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.     

Using Intact Nuts and Near Infrared Spectroscopy to Classify Macadamia Cultivars

Macadamia nut industry is increasingly gaining more space in the food market and the success of the industry and the quality are largely due to the selection of cultivars through macadamia nut breeding programs. Thus, the objective of this study was to investigate the feasibility NIRS coupled to chemometric classification methods, to build a rapid and non-invasive analytical procedure to classify different macadamia cultivars based on intact nuts. Intact nuts of five different macadamia cultivars (HAES 246, IAC 4-20, IAC 2-23, IAC 5-10, and IAC 8-17) were harvested in 2017. Two NIR reflectance spectra were collected per nut, and the mean spectra were used to chemometrics analysis. Principal component analysis-linear discriminant analysis (PCA-LDA) and genetic algorithm-linear discriminant analysis (GA-LDA) were used to develop the classifications models. The GA-LDA approach resulted in accuracy higher than 94.44%, with spectra preprocessed with Savitzky-Golay smoothing. Thus, this approach can be implemented in the macadamia industry, allowing the selection of cultivars based on intact nuts. However, it is recommended that more experimentation to include more data variability in order to increase the classification accuracy to 100%.     

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.     

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.     

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.     

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%。     

澳洲坚果粕营养成分测定与氨基酸组成评价

目的:研究分析澳洲坚果粕营养成分的含量与组成。方法:采用氨基酸自动分析仪、凯氏定氮法及蒽酮-硫酸法等方法对澳洲坚果粕中的氨基酸、蛋白质、碳水化合物等营养成分进行了测定。应用氨基酸比值系数法,以WHO/FAO氨基酸参考模式为评价标准,对必需氨基酸的组成进行了评价。结果:澳洲坚果粕含脂肪17.22%、蛋白质24.90%、碳水化合物24.78%、氨基酸17种,总量为17.84%。其必需氨基酸的构成比例基本符合食品法典委员会(FAO/WHO)的标准,氨基酸的比值系数分(SRC)为86.95。结论:澳洲坚果粕营养丰富,人体必需氨基酸种类齐全,配比均衡,是有利于人体氨基酸营养平衡的优质食品原料。     

液压压榨澳洲坚果粕酶解制备多肽工艺优化

以液压压榨澳洲坚果粕为原料,分析了其常规营养成分含量与氨基酸组成。采用碱性蛋白酶与中性蛋白酶催化酶解澳洲坚果粕蛋白制备多肽。以水解度为指标,利用单因素试验与正交试验考察了各因素对澳洲坚果粕蛋白水解度的影响。结果表明：液压压榨澳洲坚果粕中含有32.25%的蛋白质,17 种氨基酸,含量为25.05%。碱性蛋白酶各因素对澳洲坚果粕蛋白水解度影响的主次顺序为：酶解时间＞酶解温度＞加酶量＞酶解pH值＞底物质量浓度,最佳工艺条件为：酶解温度60 ℃、酶解时间3.5 h、底物质量浓度110 g/L、酶解pH 8.0、加酶量2 400 U/g,在此条件下水解度达到了22.83%。中性蛋白酶各因素影响水解度的主次顺序为：加酶量＞酶解时间＞底物质量浓度＞酶解温度＞酶解pH值,最佳工艺条件为酶解温度55 ℃、酶解时间3.5 h、底物质量浓度100 g/L、酶解pH 7.0、加酶量3 200 U/g,水解度达到了22.78%。碱性蛋白酶与中性蛋白酶各因素对澳洲坚果粕蛋白水解度的影响均达到了极显著水平（P＜0.01）。在最佳工艺条件下,碱性蛋白酶酶解液压压榨澳洲坚果粕制备多肽的效果优于中性蛋白酶。