Effect of gamma irradiation on the physico‐chemical and sensory properties of raw shelled peanuts (Arachis hypogaea L.) and pistachio nuts (Pistacia vera L.)

Abstract

BACKROUND: The present study evaluated the quality of raw peanuts and pistachio nuts as a function of irradiation dose in order to determine dose levels causing minimal undesirable changes to these products. Physico-chemical (colour, peroxide value, hexanal content, fatty acid composition, volatile compounds) and sensory (colour, texture, odour, taste) properties of raw peanuts and pistachio nuts were determined after irradiation at doses up to 7 kGy. RESULTS:Results showed an eight-and seven-fold increase in peroxide value and a twelve and five-fold increase in hexanal content after irradiation at a dose of 7 kGy for peanuts and pistachio nuts, respectively. An increase was also observed in saturated fatty acids (20.51-28.28% and 15.24-24.87%) with a parallel decrease in unsaturated fatty acids (79.49-71.72% and 84.76-75.13%) for peanuts and pistachio nuts, respectively. Likewise, volatile compounds such as aldehydes, alkanes, ketones and alcohols comprising secondary oxidation products of peanut and pistachio nut lipids increased after irradiation. Pistachio nut colour parameter a * and to a lesser extent parameters, L * and b * decreased after irradiation leading to a slight but noticeable darkening in product colour while colour parameter L * , b * and a * of raw peanut remained unchanged by irradiation up to 7 kGy. CONCLUSION: Based on sensory evaluation, peanuts and pistachio nuts become unacceptable for consumption when irradiated at doses higher than 3 kGy.

Evaluation the effect of gamma irradiation on microbial, chemical and sensorial properties of peanut (Arachis hypogaea l.) seeds

“…Gamma radiation (up to 10 kGy) and storage time (up to 6 months) increased oxidation compound production (De Camargo et al, 2012). Volatile secondary compounds such as aldehydes, ketones and alcohols have had their concentration increased in peanuts subjected to gamma radiation with doses up to 7.0 kGy (Mexis and Kontominas, 2009). Table 3 reveals lower bacterial contamination (2.68 log 10 cfu·g -1 ) in peanut seeds than fungal (3.19 log 10 cfu·g -1 ).…”

“…However, there are many publications produced by researchers from other countries on the irradiation of peanuts (Chiou et al, 1990;De Camargo et al, 2012;Mexis and Kontominas, 2009;Seda et al, 2001).…”

Physical, Proximate and Functional Properties of Flour and Protein Isolate from Four γ-Irradiated Groundnut Cultivars

“…Generally, groundnut develop and mature below the soil surface in tropical, sub-tropical and warm temperate zone [3]. The groundnut kernel is composed of roughly equal weight of fatty acid and non-fatty constituents, the relative amount of each depending upon cultivar and maturity [4]. Most of the fatty constituents are contained in the cotyledons, some are found in the germs or hearts and small amounts are located in the Testa or skins [4].…”

“…The groundnut kernel is composed of roughly equal weight of fatty acid and non-fatty constituents, the relative amount of each depending upon cultivar and maturity [4]. Most of the fatty constituents are contained in the cotyledons, some are found in the germs or hearts and small amounts are located in the Testa or skins [4]. Groundnut is rich in oil and protein and has high energy content; it supplies about 5.6 calories per grain when consumed raw and 5.8 calories per grain when consumed roasted [5].…”

“…The seed testa constitutes 4% to 5%, cotyledon 92% to 94%, and germ 3% to 4% of the seed mass [8]. The testa is composed of carbohydrate cellulose, protein, and phenolic compounds, while cotyledons have mainly oil and protein, the germ contain high proportion of protein, reducing sugar and disaccharides [4,9]. The nuts of Arachis hypogeae contain 25, 48, 20, 2.1% crude protein, crude fat, carbohydrates and crude fibre, respectively, with a high content (87%) of unsaturated fatty acids [10,11].…”