Evaluation of new Turkish hybrid hazelnut (Corylus avellana L.) varieties: fatty acid composition, α-tocopherol content,mineral composition and stability

Five new hybrids (T. Kolon, H190, H260, H262, H580) of Turkish hazelnut varieties were evaluated in terms of total oil, fatty acid composition, α-tocopherol, unsaturated/saturated ratio, stability index and mineral in comparison with five commercial Turkish hazelnut varieties (Tombul, Palaz, Mincane, Foşa and Çakıldak). Significant differences in total oil, fatty acid composition, stability index, α-tocopherol content and mineral composition were observed between varieties. The highest stability index values were observed in commercial Tombul (6.29), Foşa (5.93) and Palaz (5.42) varieties. No significant advantage of new hybrid varieties over commercial varieties was observed in terms of stability of hazelnuts.     

Rice vinegars of different origins: discriminative characteristics based on solid‐phase microextraction and gas chromatography with mass spectrometry,an electronic nose,electronic tongue and sensory evaluation

Eight kinds of commercial rice vinegars from Korea, China and Japan were selected to evaluate their flavour‐related discriminative characteristics based on solid‐phase microextraction and gas chromatography with mass spectrometry (SPME/GC–MS), an electronic nose (e‐nose), electronic tongue (e‐tongue) and subjective sensory evaluation. Principal component analysis patterns based on SPME/GC–MS provided a clear categorical discrimination among the vinegars of three origins. The distribution patterns of the samples were similar between SPME/GC–MS and e‐nose analyses and Korean vinegars were clearly discriminated. A high correlation coefficient was determined between SPME/GC–MS and e‐nose on acetaldehyde (0.948) and diacetyl (0.970). e‐Tongue‐based principal component analysis patterns were subdivided into three regions according to the origin, and Chinese vinegars were clearly discriminated. Sensory panelists recorded origin‐specific scores on flavours for all the samples. In conclusion, SPME/GC–MS, e‐nose and e‐tongue analyses may be useful for discrimination of flavour profiles of rice vinegars of different producer origin. Copyright © 2017 The Institute of Brewing & Distilling     

8种抗寒平欧杂交榛子油脂成分分析及比较

比较8种平欧榛子的差异性,利用索氏提取法测定油脂含量,气相色谱法和比色法进行油脂脂肪酸组成和α-VE含量分析,聚类分析用于区分其类别。结果表明:8种平欧榛子有显著差异,含油量平均为56.36%,范围为52.92%~59.24%;单不饱和脂肪酸、多不饱和脂肪酸、饱和脂肪酸的平均相对含量分别为72.54%、16.11%、7.85%;最丰富的脂肪酸是油酸,平均相对含量为72.29%,亚油酸与油酸总含量超过85%;α-VE含量为113.42~285.16μg/g。用3个主成分PC1(43.384%)、PC2(34.436%)、PC3(12.606%)作为合成变量通过聚类分析可得到4个类群:4#、5#、6#、7#为一类,8#为一类,2#、3#为一类,1#为一类。     

The thermal kinetics of texture change and the analysis of texture variability for raw and roasted hazelnuts

Texture changes of hazelnuts which were dry roasted at temperatures from 120 to 180 °C, for durations ranging from 5 up to 60 min, were studied using instrumental analysis. The textural changes in hazelnuts were represented by the fracture force obtained from compression tests. The magnitudes of the parameters for the corresponding texture change model were determined using one step non‐linear regression. The order of the reaction was found by plotting isothermal curves of texture response against time; statistical analysis of the data showed that it was best represented by a first‐order reaction. The rate constants were assumed to have an Arrhenius‐type dependence on temperature. The activation energy and the frequency (pre‐exponential) factor at a reference temperature (150 °C) were determined to be 39.25 kJ mol^?1 and 0.0421 s^?1, respectively. Young's modulus and the fracture stress for roasted hazelnuts were calculated to be 4.93 and 1.54 MPa, respectively. Both roasting temperature and time had significant effects on the textural changes in hazelnuts, and the variability in the texture decreased during the roasting process. The physical properties of hazelnuts were correlated with the texture response. A possible major factor causing the high variability in texture was the internal cavity present at the core of each hazelnut. The development of a model of the thermal kinetics of texture change over a large roasting temperature and time range should allow optimization studies to be used for determining the best roasting schedule in terms of delivering the required product texture.     

Variations in volatile compounds and flavour in Idiazabal cheese manufactured from ewe's milk in farmhouse and factory

Stage of lactation, use of bulk milk or milk from individual flocks, and cheese‐making in farmhouse or industrial factory are important factors affecting the production and quality of Idiazabal cheese. The volatile composition of cheese samples made from raw ewe's milk in farmhouses or industrial plants at two different times of the year and aged for 90 and 180 days was analysed by dynamic headspace coupled to GC‐MS. Short‐chain fatty acids, primary and secondary alcohols, methyl ketones and ethyl esters were the most abundant compounds in the aroma of Idiazabal cheese samples. Differences in the volatile composition were found between farmhouse and industrial cheeses made at different times of the year and ripened for 90 or 180 days. Likewise, the sensory profiles of the farmhouse and industrial cheeses were significantly different, regardless of the time of the year and ripening time. The results for the principal component analysis (PCA) performed on the sensory attributes of the cheese samples showed two PCs defined as ‘farmhouse flavour factor’ and ‘industrial flavour factor’. Farmhouse cheeses showed high scores for buttery, milky and toasty odours, and buttery and nutty flavours, whereas industrial cheeses showed high scores for sharp, rennet and brine odours, and rennet and rancid flavours. The percentages of methyl ketones such as 3‐hydroxy‐2‐butanone, 2‐butanone, 2‐pentanone and 2‐heptanone, and acids such as n‐propanoic, 2‐methylpropanoic and 3‐methylbutanoic acids were higher in farmhouse cheeses than in industrial cheeses. On the other hand, the percentages of esters such as ethyl butanoate and ethyl hexanoate, and alcohols such as 3‐methyl‐1‐butanol, and acids like n‐hexanoic acid were higher in industrial cheeses than in farmhouse cheeses. Relationships between sensory attributes and volatile compounds were studied on the basis of the differences found in sensory profile and volatile composition between farmhouse and industrial cheeses. Copyright © 2005 Society of Chemical Industry     

利用电子鼻区分不同产地、不同品种的烤烟

为了探索区分不同产地、不同品种烤烟的有效方法,利用电子鼻检测了3个地区（贵州、云南、辽宁）共70种烤烟样品的挥发性成分,并对电子鼻采集数据分别进行主成分分析、聚类分析和判别函数分析。通过判别函数分析方法所建立模型对测试集样品的正确判别率达到91.7%,结果表明电子鼻方法可以有效地区分不同产地、不同品种的烤烟,该方法可为人工鉴定烤烟提供参考。      

Lipid characteristics and essential minerals of native Turkish hazelnut varieties (Corylus avellana L.)

Five native hazelnut varieties from Turkey, namely, prime quality Tombul variety, and second grade quality Yass? Badem, Sivri, Karaf?nd?k, and Ham varieties were examined for their lipid characteristics (triacylglycerol, tocopherol, tocotrienol, phytosterol, and phytostanol composition) and 12 essential minerals. Among 12 triacylglycerols separated in all hazelnut varieties, OOO (61.0–77.5%) and OOL (10.5–22.8%) were the main components (where O = oleoyl and L = linoleoyl). Seven tocol isoforms (four tocopherols and three tocotrienols), seven phytosterols, as well as cholesterol, and one phytostanol were positively identified and quantified; among these, α-tocopherol and β-sitosterol were predominant in all hazelnut oils. Hazelnut varieties served as an excellent source of copper and manganese. Consumption of the recommended daily amount of 42.5 g of hazelnut from different varieties provides 44.4–83.6% of copper and 40.1–448% of recommended manganese intake for adults. These results suggest that second grade quality hazelnut varieties were as good sources of functional lipids and essential minerals as was prime quality Tombul hazelnut, with some exceptions (P < 0.05).     

The potential of different techniques for volatile compounds analysis coupled with PCA for the detection of the adulteration of olive oil with hazelnut oil

This paper investigates the effectiveness of three rapid methods of volatile compounds analysis with subsequent principal component analysis (PCA) treatment of data for differentiation between virgin olive oil samples adulterated with hazelnut oil. Tested methods included comparison of chromatograms of volatiles obtained using SPME-fast GC-FID, volatiles analysis by electronic nose based on MOS sensors (HS-Enose), and by direct coupling of SPME to MS (SPME-MS). Volatile compounds were analyzed also by SPME-GC/MS technique. Data obtained as a result of SPME-GC/MS was subjected to PCA. SPME-GC–MS analysis with subsequent PCA yielded good results, however being time consuming. The three methods of analysis of volatiles, with subsequent PCA treatment of data, allowed detection of olive oil adulteration with different contents of hazelnut oil ranging from 5 to 50% (v/v).     

Aflatoxin levels in raw and processed hazelnuts in Turkey

Aflatoxin levels in hazelnut samples obtained from exporter companies were monitored over a 3-year period. A total of 3188 samples of raw and processed hazelnuts were analysed using an HPLC method. The total aflatoxin content of the contaminated samples was in the range of 0.02–78.98?µg?kg^?1 for hazelnut kernels, 0.07–43.59?µg?kg^?1 for roasted hazelnut kernels, 0.02–39.17?µg?kg^?1 for roasted sliced hazelnut kernels, and 0.02–11.20?µg?kg^?1 for hazelnut purees, respectively, showing that the variations of aflatoxin contamination were very high. The results of aflatoxin analysis revealed that the aflatoxin contamination in the hazelnut samples was at a tolerable level. A total of 3147 samples were contaminated with aflatoxins, although below the legal limits. However, the aflatoxin contents of 41 samples exceeded the legal limits. Therefore, aflatoxin contents of hazelnuts should be monitored regularly to minimise the risk of aflatoxin hazard, and pre- and post-harvest strategies should be developed to prevent aflatoxin formation.     

Flavour characteristics of Ilex paraguariensis infusion,a typical Argentine product,assessed by sensory evaluation and electronic nose

Sensory evaluation and electronic nose (E‐nose) technology were applied to study two formulations of a new product intended to have organoleptic characteristics similar to those of Ilex paraguariensis (Saint Hilaire) infusions. Infusions prepared from I paraguariensis, called ‘yerba mate’ in South America, possess distinct sensory properties that were described by trained panellists using a lexicon of 17 terms. The two commercial products were formulated by combining various flavour components and processed as instant powders for infusion. Results from the sensory panel showed that it would be necessary to change the product formulation in order to achieve desirable yerba mate characteristics. Odour, mouthfeel and sweetness intensities would have to be improved. The E‐nose had an array of 32 sensors which were able to discriminate between infusions prepared from yerba mate and from the instant powders. Using stepwise discriminant analysis, the group of sensors that contributed to this classification was identified. The response of these sensors correlated (P < 0.05) with yerba mate odour, mouthfeel and sweetness attributes. Comparison of the results obtained by the two methodologies enabled the E‐nose procedure to be improved and showed that this methodology is suitable for food product development and is a good complement to sensory evaluation. Copyright © 2004 Society of Chemical Industry