Mycoflora of hazelnut (Corylus avellana L.) and aflatoxin content in hazelnut kernels artificially infected with Aspergillus parasiticus

In this research, 30 hazelnut samples were used to determine their internal mould populations and their aflatoxin contents. The results showed that Aspergillus was the most common genus in the experimental samples (96.6% of all samples). Thirty-one% of isolates were classified as Aspergillus flavus and none of the samples contained aflatoxins. In the second part of the experiment, the kernels were inoculated with conidia of Aspergillus parasiticus and incubated at three different humidified conditions and two different temperatures for 45 days. Aflatoxin contents of the samples kept in 98% relative humidity and at 28 degrees C were higher (904.6 micrograms/kg) than that of the other samples. On the other hand, no aflatoxin was detected in the control samples that were not inoculated but kept at the same conditions.     

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     

Characterization of several hazelnut (Corylus avellana L.) cultivars based in chemical, fatty acid and sterol composition

Nineteen cultivars of hazelnuts (Corylus avellana L.) collected during the 2001 crop, from Vila Real, Portugal, were analysed for chemical composition, including moisture, total oil content, crude protein, ash, carbohydrates and nutritional value. Fat was the predominant component, ranging from 59.3 to 69.0%. Total oil was extracted and analysed for fatty acid and sterol compositions and oxidative stability. Fatty acid and sterol compositions were determined by Gas–Liquid Chromatography coupled to a Flame Ionisation Detector (GLC/FID). Monounsaturated fatty acids, particularly oleic acid, were predominant (78.7–84.6%). Total phytosterol content ranged from 133.8 to 263.0 mg/100 g of oil. Among the nine sterols identified and quantified, β-sitosterol was the major one with a mean percentage of 83.6%, while Δ⁵-avenasterol and campesterol were the second and the third components of the group with mean values of 6.1 and 5.8%, respectively. Since hazelnut oil can be used in olive oil adulteration, the values obtained were compared with published mean values of olive oils from different geographical origins.     

Effects of geographical origin and variety on vitamin and mineral composition of hazelnut (Corylus avellana L.) varieties cultivated in Turkey

The effects of variety and geographical origin on vitamin and mineral composition of eight different varieties of hazelnut cultivated in the Black Sea Region of Turkey were studied. The mean contents of niacin, vitamin B₁, vitamin B₂, vitamin B₆ and α-tocopherol were 1.81±0.28, 0.30±0.07, 0.10±0.01, 0.240±0.05, and 35.53±3.82 mg/100 g, respectively. The mean contents of iron, zinc, copper, magnesium, manganese, calcium, potassium and sodium were 2.32±0.21, 1.95±0.25, 0.65±0.29, 144±14.86, 6.09±4.17, 83.5±5.14, 637±105.33 and 0.70±0.10 mg/100 g, respectively. Vitamin and mineral compositions of the varieties were not significantly different from each other. Geographical region differences did not significantly affect α-tocopherol, iron, manganese and calcium contents of the samples. Zinc, manganese, and sodium levels of Akçakoca samples were higher than for the other regions. Correlation analysis showed that α-tocopherol content correlated strongly with minerals (manganese, sodium, zinc, potassium) and vitamin B₆.     

Factors influencing fungal and aflatoxin levels in Turkish hazelnuts (Corylus avellana L.) during growth, harvest, drying and storage: A 3-year study

The levels aflatoxins in Turkish hazelnuts have been monitored over a 3-years period (2002-2004). Periodical sampling was made in 72 different orchards at different locations representative of the hazelnut-growing areas and post-harvest applications. Various parameters (aflatoxins, water activity, moulds) were analysed and environmental conditions (temperature and relative humidity) recorded during growing and at different stages of harvest and post-harvest processing, involving three different harvesting methods (collection in nets, from the ground, etc.) and four drying techniques (traditional sun-drying, mechanical drying, etc.). Fungal and aflatoxin analyses (HPLC) showed no significant difference except between samples which had been in contact with the ground and those which had not (at 95% confidence level). Aflatoxins levels from the orchard recorded a maximum of 0.77 ± 0.08 ng g^-1 from a total of 1624 samples. Regarding harvesting and post-harvest processes, the only application where aflatoxins were detected was in samples which had been in direct contact with the ground (max. 3.18 ± 0.03 ng g^-1). Aflatoxin formation was low during storage (max. 0.34 ± 0.003 ng g^-1). As a result of mycological studies, a total of 5546 Aspergillus flavus (89%) and A. parasiticus (11%) species were isolated and identified from samples. The results indicated that harvesting hazelnuts into a canvas by shaking the trees, manual harvesting of mature hazelnuts where possible, use of jute instead of nylon sacks and mechanical drying technique would minimize aflatoxin levels in hazelnuts. These recommendations have been implemented and about 4000 people in the hazelnut industry have been trained in these practices.     

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。     

Identification of volatile components in basil (Ocimum basilicum L.) and thyme leaves (Thymus vulgaris L.) and their antioxidant properties

Aroma compounds in the extracts of basil leaves (Ocimum basilicum L.) and thyme leaves (Thymus vulgaris L.) were identified by gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). The major aroma constituents of basil were 3,7-dimethyl-1,6-octadien-3-ol (linalool; 3.94 mg/g), 1-methoxy-4-(2-propenyl) benzene (estragole; 2.03 mg/g), methyl cinnamate (1.28 mg/g), 4-allyl-2-methoxyphenol (eugenol; 0.896 mg/g), and 1,8-cineole (0.288 mg/g). The major aroma constituents of thyme were 2-isopropyl-5-methylphenol (thymol; 8.55 mg/g), 4-isopropyl-2-methylphenol (carvacrol; 0.681 mg/g), linalool (0.471 mg/g), α-terpineol (0.291 mg/g), and 1,8-cineole (0.245 mg/g). Twelve aroma constituents of basil and thyme were examined for their antioxidant activities using the aldehyde/carboxylic acid assay. Eugenol, thymol, carvacrol, and 4-allylphenol showed stronger antioxidant activities than did the other components tested in the assay. They all inhibited the oxidation of hexanal by almost 100% for a period of 30 days at a concentration of 5 μg/ml. Their antioxidant activities were comparable to those of the known antioxidants, α-tocopherol and butylated hydroxy toluene (BHT).     

Functional properties of wheat kernels (Triticumaestivum L.) during storage

The method of storage has, in the long run, a negative effect on the quality of wheat kernels, due to physiological ageing of its cells.The quality of the kernels was assessed during the storage, giving the predefined conditions - temperature 25 ± 2 °C and the storage duration.Wheat kernel metabolites were studied during 12 and 24-month storage. Kernels of three commercial wheat cultivars – ‘Simonida’, ‘Dragana’ and ‘Ljiljana’, commonly grown in south-eastern Europe, were investigated. Comparing fresh samples to samples taken after 12 and 24 months of storage, it was recorded with an increase in dry matter (by 2.48% and 2.84%) and ash (by 4.09% and 15.25%), and a decrease in protein (by 8.96% and 19.81%), lipids (by 8.32% and 15.07%), starch (by 9.07% and 13.45%) and cellulose (by 22.12% and 26.35%). There were also changes in phenolics (10.51–11.82 mg GA/g). Flavonoid vitexin-glucoside (0.82–1.29 mg/g) and flavan-3-ol catechin (1.31–1.60 mg/g), total antioxidant potential and DPPH scavenging activity were not significantly different. Organic matter digestibility (OMD) decreased, but remained at 92%. These changes did not significantly affect key properties of the kernels, OMD and antioxidant activity, thus wheat kernels can be safely stored for 24 months.     

Effect of high pressure processing on the physicochemical and sensorial properties of scallop (Mizuhopecten yessoensis) during iced storage

Scallops are the third largest aquaculture mollusks product, while they are highly perishable during storage. The main purpose of the present study was to evaluate the effect of high pressure processing (HPP) on physicochemical and sensorial properties of scallop (Mizuhopecten yessoensis) during refrigeration storage. The scallop adductor muscle was treated with different pressures (200, 300, 400 and 500 MPa, 5 min) and iced storage for 28 days. Results showed that HPP delayed microbial growth as pressure increased. HPP (≥400 MPa) resulted in myosin and actin denaturation, increased hardness, whiteness, pH and promoted water migration. However, preliminary sensory analysis showed no significant difference between pressure-treated and control adductor muscles in appearance, odour, texture and overall acceptability after cooking. In addition, pressure-treated adductor muscles (≥300 MPa) remained edible after 28 days of storage. Overall, these results can provide basic knowledge for the storage of pressure-treated scallop meat.     

Effect of carboxymethyl cellulose/candelilla wax coating containing ascorbic acid on quality of walnut (Juglans regia L.) kernels

Walnut kernels were coated with carboxymethyl cellulose (CMC)‐based emulsion with and without l ‐ascorbic acid (AA). The thickness of the coatings formed on the walnuts ranged from 12 to 360 μm. The results obtained from the thiobarbituric acid‐reactive substance analysis showed that the coating retarded lipid oxidation in walnuts during long‐term storage. The antioxidative action of the CMC‐based coating was not enhanced by incorporation of AA. On the other hand, the coating with AA slightly delayed hydrolytic rancidity of walnuts. More smooth and homogenous surface of walnuts coated with AA led to higher gloss. The acidifying/reductive action of AA lightened the colour of walnuts. Coating (dipping and drying) resulted in partial loss of aromaticity of walnuts.