ارزیابی محتوی آلفا و گاماتوکوفرول در بادام درختی، فندق، بادام‌زمینی و پسته در طی فرآیند برشته کردن

برشته کردن یکی از فرآیندهایی است که مقدار ترکیبات مغزهای خوراکی را تغییر می‌دهد. هدف از این مطالعه بررسی تاثیر شرایط برشته کردن بر میزان محتوی آلفا و گاماتوکوفرول بود. در مطالعه حاضر، اثر دما (120 و 150 درجه سانتی‌گراد)، و زمان (صفر، 20، 30 و 40 دقیقه) برشته کردن بر میزان آلفاتوکوفرول و گاماتوکوفرول باقی مانده در چهار مغز بادام درختی، فندق، بادام‌زمینی و پسته مورد بررسی قرار گرفت. برشته کردن یکی از روش‌های معمول فرآوری مغزهای خام بوده که می‌تواند بر مقدار توکوفرول مغزها اثر بالایی داشته باشد. نتایج نشان دادند که مقدار آلفاتوکوفرول بادام درختی در دمای 120 درجه سانتی‌گراد و گاماتوکوفرول در هر دو دمای اعمالی در طول 20 دقیقه ابتدایی برشته کردن افزایش یافته ولی با ادامه فرآیند تا 40 دقیقه مقدار آن کاهش یافت. در فندق، بادام‌زمینی و پسته نیز مقدار آلفا و گاماتوکوفرول تا دقیقه 20، افزایش یافته ولی در ادامه حرارت‌دهی کاهش یافت. به‌طور کلی در دمای 150 درجه سانتی‌گراد، پس از 20 دقیقه میزان توکوفرول مغزها شروع به کاهش کرد در حالی که در دمای 120 درجه سانتی‌گراد روند کاهشی پس از 30 دقیقه نمود یافت. افزایش مقدار توکوفرول‌ها در ابتدای برشته کردن به سبب آسیب دیواره‌های سلولی بوده و توکوفرول‌های متصل به ترکیباتی همچون فسفولیپیدها با سهولت بیشتری خارج می‌شوند. در ادامه برشته کردن، به دلیل حساسیت این ترکیبات به حرارت، تجزیه حرارتی آنها رخ داده و کاهش می‌یابند.

Evaluation of alpha and gamma tocopherol content of almond, hazelnut, peanut and pistachio during roasting process

Introductıon: Nuts are one of the major resources of bioactive compounds such as tocopherols, tocotrienols, sterols (Jensen and Lauridsen, 2007). Tocopherols include 8 natural homologues that all of them belongs to vitamin E group (Chun, 2002). It is well known that vitamin E has good antioxidant activity and among its isomers, αtocopherol and γtocopherol have highest biological activity and free radical scavenging, respectively (Grilo et al., 2014). In recent years, the beneficial health effects of vitamin E on some disease such as cancer and heart disorders attract researcher’s attentions (Wagner et al., 2004).Roasting process changes the chemical and nutritional properties of nuts, including antioxidants, vitamins, colors, and aroma mostly through Maillard reaction (Alamprese et al., 2009، Ballistreri et al., 2009). Due to the importance of vitamin E antioxidant activity and its heat sensitivity, the residual amounts of them after different roasting conditions were investigated. & nbsp، & nbsp،Materials and methods: Samples were spreaded in alominum foil and placed in forced air oven at 120 and 150 ºC and different time intervals including 0, 20, 30 and 40 min. After roasting, samples were powdered, then 0.5 g of each sample plus 0.05 g ascorbic acid were added to 0.5 mL ethanol (90.2%) and 0.5 mL KOH and mixed in a tube (16× 125 mm). The tube was then placed in water bath for 30 min. Then, the tube were placed in ice bath for 5 min, then 3 mL deionized water, 5 mL hexane were added to the tube and vortexed for 30 s and centrifuged for 10 min at 1000 rad/s at ambient temperature. The extraction was done twice. Hexane layer evaporated with nitrogen then 1 mL of mobile phase added to tube and vortexed again. Prepared samples then were injected to HPLC (Knuer Germany). & nbsp،Results and discusion: Based on the obtained results, αtocopherol content in almond was more than γtocopherol. After 20 and 30 min of roasting, at 150 and 120 ºC respectively, the amount of αtocopherol slightly increased, while it decreased with increasing roasting time. γtocopherol content in almond at both temperatures also increased up to 20 min roasting and decreased till the end of process. In hazelnut, at both temperatures up to 20 min and then decreased till end of roasting process. This trend was shown for peanut tocopherols as well. With increasing in roasting time, αtocopherol and γtocopherol content decreased to their initial level. It has suggested that tocopherols which attached to the other components such as phospholipids released more conveniently under thermal treatment like roasting which leads to increase their concentrations at initial of thermal process. In pistachio, 150 and 120 ºC respectively caused to increase in γtocopherol content, respectively while its content decreased up to the end of roasting time (40 min). αtocopherol content at both temperatures increased after 20 min, then decreased gradually as time passes. Results indicated that both time and temperature of roasting had a significant effect on α and γtocopherol of four nuts. Although both of temperatures in our study significantly on increased vitamin E isomers at the start of roasting process, their contents decreased with increasing in roasting time. Maximum amount of both isomers were detected at 120 ºC after 30 min and at 150 ºC after 20 min.