NUTRIENTS AND BIOCHEMISTRY OF NUTS IN DIFFERENT CONSUMPTION TYPES IN TURKEY

Abstract

Nuts have high nutritive value and have different kinds of consumption properties in some food treatments such as salting, roasting, vacuum packaging or under inert gas. The quality of nuts are affected by biochemical changes such as oxidation and rancidity in nut oils, which contain polyunsaturated fatty acids. In this research, the nutrients, proximate composition and minerals, and biochemical changes in nuts were determined according to consumption types: hazelnuts (Corylus avelana L.), peanuts (Arachis hypogaea L.) and pistachio nuts (Pistacia vera L.). In Turkey, the consumption types of nuts depend on some food treatments such as roasting, salting, vacuum packaging and eating habits such as shelled, unshelled, unroasted and even fresh nuts or combinations of them. The storage periods of the samples which were almost 2 weeks in the market were very short. The protein contents of groundnuts were higher than hazelnuts and pistachio nuts. The fat contents of pistachio nuts were higher than hazelnut and groundnut samples. The total carbohydrate levels of hazelnuts and groundnuts were almost same and were higher than pistachio nuts. Moisture content is the highest for hazelnuts and pistachio nuts, respectively. The mean mineral contents of these nuts are (mg/100 g) Na (0.98, 1.30, 9.38), Mg (140.09, 173.47, 116.90), K (514.01, 558.22, 642.07), Ca (106.16, 67.29, 171.69), Cu (0.99, 0.75, 0.75), Zn (2.96, 0.44, 2.77) and Fe (0.56, 0.41, 0.58). The biochemical changes in nuts were examined in nut oils, iodine value, free fatty acids, anisidine value, UV absorption (λ: 233, 262, 268 and 272 nm). The results had shown that important quality changes did not occur as explained in the conditions of the research samples. Also, positive correlation among the nut samples had not been found. It was established that the changes in the biochemical values depend on the polyunsaturated fatty acids composition of nut oil. The results of the analysis of the levels of oxidation had exhibited differences among the nut oil samples because of polyunsaturated fatty acids ratios rather than because of the different kinds of consuming properties.