Inhibition of egg and larval development of the Indian meal moth Plodia interpunctella (Hübner) and almond moth Ephestia cautella (Walker) by gamma radiation in decorticated hazelnuts

In this study, inhibition of egg hatching and development of immature stages of the Indian meal moth and almond moth by irradiation in hazelnuts was investigated. Irradiation doses required to inhibit the development of eggs of Plodia interpunctella and Ephestia cautella were 450 and 300 Gy, respectively, and no adults of either species emerged from treated samples (all stages) at 1 kGy of radiation in large-scale tests. The low-dose irradiation treatment did not cause excessive oxidative deterioration and no significant differences were found in organoleptic studies at 0.5-3 kGy in decorticated hazelnuts. However, total tocopherol content decreased depending on irradiation dose.     

Detection of hazelnut oil in virgin olive oil by a spectrofluorimetric method

The possibilities of a spectrofluorimetric method joined to multivariate analysis to assess the genuineness of olive oil in admixtures with hazelnut oils were studied. Virgin olive, virgin hazelnut and refined hazelnut oil samples and admixtures between them at 5, 10, 15, 20, 25 and 30% adulteration were analysed at _ex=350 nm. The precision of the method, in terms of repeatability and internal reproducibility, was established by means of the analysis of a virgin olive oil sample under different conditions, the RSD showing values less than 10%. Raw data of the spectra were subjected to mathematical treatment by calculation of the first derivative, selection of the maximum values and application of one-way ANOVA, to assess the most prominent variables in the discrimination process. The response to the addition of adulterant was linear, adjusted-R²=0.99 for virgin olive and refined hazelnut oil mixtures, and 0.98 for virgin olive and virgin hazelnut oil mixtures. Stepwise linear discriminant analysis applied to each admixture separately and to the whole set of samples allowed 100% correct classifications.     

Influence of Drying Conditions on the Hazelnut Quality. II. Enzymatic Activity

The influence of the drying conditions on the enzymatic activity in hazelnut (Corylus avellana, L.) has been studied. In this work, the activity of the enzymes lipase. peroxidase and polyphenoloxidase have been determined in hazelnuts dried under three temperatures (30, 50 and 70°C). The drying experiments were done with forced air circulation, and samples of Negret variety. unshelled and shelled, were used. It has been observed that the drying process reduces the activity of the enzymes lipase, peroxidase and polyphenoloxidase in hazelnut, and the results indicated that polyphenoloxidase is the most unstable to heat.     

Influence of Drying Conditions on the Hazelnut Quality. II. Enzymatic Activity

ABSTRACT

The influence of the drying conditions on the enzymatic activity in hazelnut (Corylus avellana, L.) has been studied. In this work, the activity of the enzymes lipase. peroxidase and polyphenoloxidase have been determined in hazelnuts dried under three temperatures (30, 50 and 70°C). The drying experiments were done with forced air circulation, and samples of Negret variety. unshelled and shelled, were used. It has been observed that the drying process reduces the activity of the enzymes lipase, peroxidase and polyphenoloxidase in hazelnut, and the results indicated that polyphenoloxidase is the most unstable to heat.     

Phytosterols in 17 Turkish hazelnut (Corylus avellana L.) cultivars

The phytosterol contents of the oils from 17 Turkish hazelnut cultivars were determined by gas chromatography with a flame ionization detector. The total phytosterol content varied from 1180.4 (Uzunmusa‐Ordu) to 2239.4 mg/kg (Cavcava), and the average was 1581.6 ± 265.1 mg/kg. One of the most significant commercial cultivars, Tombul, contained quite low total phytosterols (1297.7 mg/kg). Total and individual phytosterol contents of hazelnut cultivars were significantly different at p <0.01, except for phytostanol and campestanol. The main component was β‐sitosterol which ranged from 82.8 to 86.7% in all cultivars. This was followed by campesterol, Δ⁵‐avenasterol, sitostanol and stigmasterol. Interestingly, the same cultivars from different regions showed similar total phytosterol contents, and fall almost within the same range according to Duncan's test, which may indicate that the phytosterol content is highly related to the cultivar.     

Effect of replacing beef fat with hazelnut oil on quality characteristics of sucuk - A Turkish fermented sausage

Turkish fermented sausages (sucuk) were produced by replacing 15, 30 and 50% of beef fat with hazelnut oil incorporated as pre-emulsified with simplesse^® 100 (whey protein powder) Each treatment was formulated to contain 20% total fat and beef fat was the only fat material used in the control (C) group. After 12 days of fermentation and ripening, all sucuk samples had TBA values within acceptable limits (<1.0). Increasing levels of hazelnut oil in sucuk formulation increased penetrometer values (softer texture) and moisture content. Hazelnut oil replacement had a significant effect on redness values of the samples. Cholesterol content decreased progressively as the percentage of hazelnut oil increased in the formulation. Replacement of 50% beef fat with 50% hazelnut oil significantly increased MUFA, PUFA and MUFA + PUFA/SFA ratios. The use of hazelnut oil resulted in significant decreases in the slice appearance, texture and taste scores. However there was no significant difference in the overall acceptability score of samples, except those in which hazelnut oil replaced 15% beef fat, which had the highest score.     

Rancidity in hazelnuts due to volatile aliphatic aldehydes

Hazelnut kernels became rancid on storage under ambient conditions in the presence of air. The kernels have a high oil content. The oil contains approximately 75 g per 100 g oleic acid (18:1) and 9 g per 100 g linoleic acid (18:2). Rancidity was detected organoleptically, by gas chromatography/mass spectrometry of the volatile off-flavour compounds and by reduction in both the total fatty acid content (g per 100 g oil) and the iodine value (g per 100 g oil). There was an accumulation of volatile alkanals, 2-alkenals and alkanoic acids on storage of the kernels at ambient temperature in the presence of oxygen. Hexanal (derived from oxidation of linoleic acid) and octanal (derived from oxidation of oleic acid) increased over tenfold on storage, whilst there was concomitant decrease in fatty acid content (83 g per 100 g oil) and iodine value (79) during the same period. It is suggested that analysis of volatile aldehydes such as hexanal and octanal could be used to assess rancidity in foods or oils rather than relatively nonspecific tests such as iodine or peroxide value. There was no evidence in this work that the rancidity was due to microbial spoilage.