Effects of different roasting methods on formation of acrylamide in pistachio

Abstract

Drying and roasting are conventional processes in the nut industry. However, roasting as an important procedure in nuts manufacturing may cause some physicochemical changes in nuts. Acrylamide is one of these chemical compounds that is formed due to the roasting process. Acrylamide is known as a neurotoxicant, carcinogen, and reproductive toxicant. In this study, raw and salted pistachios were roasted under three conditions including hot‐air, infrared (IR), and microwave methods. Then, 80 pistachio kernels were analyzed by ultra‐high‐performance liquid chromatography. The results showed that all samples contained different ranges of acrylamide between 57 ± 0.86 and 851 ± 2.8 μg/kg. Besides, raw pistachios and sun‐dried pistachios also contained acrylamide, with the amount of 57 ± 0.86 and 93 ± 1.07 μg/kg, respectively. The highest acrylamide amount was found in raw pistachio (unsalted) roasted by IR method, while lower acrylamide amount observed in the microwave method. The amount of acrylamide in salted and roasted pistachios was less than just roasted pistachios under the same conditions. Finally, in all the treatments, increasing temperature, time, voltage, and power lead to an increase in acrylamide levels. The results showed that acrylamide in the roasted pistachios may cause health problems. This study presents a novel investigation in the effects of roasting conditions (temperature, power, voltage, and time) on acrylamide content in pistachios.

Effect of Microwave Heating on the Acrylamide Formation in Foods

“…Various factors affect the reaction yields of acrylamide, such as heat processing method, heating temperature, heating time, concentrations and types of sugar compounds, and water content. This main effect of temperature and time in heat processing methods on acrylamide formation has been reported by many researchers [ 4 , 6 , 12 , 15 , 35 , 80 , 81 , 82 , 83 , 84 , 85 ]. Some studies indicate that microwave processing can facilitate Maillard reactions as with conventional heating methods.…”

“…Elfaitouri et al [ 97 ] reported, that the increase of the power used during frying potato chips from 200 W to 800 W (with the temperature increase from 160 °C to 180 °C) increases the acrylamide content several times. Although they did not show such clear trends associated with duration of the frying process, the relationship of increasing acrylamide content with increasing the time of microwave food processing was confirmed by other authors [ 12 , 35 , 83 , 89 ]. Chen et al [ 90 ] reported that with the extension of the microwave heating time of shrimp chips from 40 s to 80 s, the acrylamide content increased almost 20 times (the process was carried out at 900 W).…”

“…Sansano et al [ 94 ] indicated that microwave frying resulted in AA reduction ranging from 37% to 83% compared to deep-oil frying. Asadi et al [ 12 ] showed, that microwave roasting of pistachios produces less acrylamide (119 µg/kg), than during the IR method (318 µg/kg), or using hot air (204 µg/g) ( Table 2 ). The effect of microwave frying on acrylamide formation was also investigated in the coating part of chicken.…”

“…In addition to the use of the enzyme and the black cumin seeds mentioned above, it is advised to also use other compounds that can reduce the content of acrylamide formed during food processing. Asadi et al [ 12 ] indicated that the addition of salt affects the formation of acrylamide in microwave-heated pistachios ( Table 2 ). Microwave roasting of salted pistachios resulted in the formation of smaller amounts of acrylamide, compared to unsalted products roasted at the same time, which, according to the authors, was related to their water content.…”

“…Moreover, it is believed that not only heating temperature and time are the most important factors in the formation of hazardous compounds in foods. The heat treatment methods can also be responsible for food toxicant formation (their type and level) [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 ]. In recent years, new technologies such as microwave heating have experienced increased popularity as alternatives to conventional processing methods having various applications in the food industry and foods prepared at home, by catering services or served in restaurants.…”