Effects of different cooking and drying methods on phenolic acids, carotenoids, and antioxidant activity of emmer (Triticum turgidum ssp. dicoccum) bulgur

Abstract

Background and objectives Emmer (Triticum turgidum ssp. dicoccum) is an ancient hulled wheat with a high amount of nutrient and bioactive compounds. This study was aimed to investigate the changes in bioactive compounds and antioxidant activities of the emmer bulgurs produced by combinations of three cooking (traditional, autoclave, and microwave) and two drying (hot air and microwave) methods. The total polyphenol, carotenoid, antioxidant activity (DPPH radical scavenging activity and ferric reducing antioxidant power), and soluble‐free (SF), soluble‐conjugated (SC) and insoluble‐bound (IB) phenolic acid contents were determined. Findings Bioactive compounds and antioxidant activity decreased significantly in all bulgur production methods compared to emmer wheat. SF and SC phenolic acids of the bulgur samples decreased much more than IB phenolic acids, due to the better thermal stability of IB fraction. While microwave cooking was found to have a positive effect, microwave drying had a negative effect on preserving natural bioactive compounds. Conclusions The bulgur preparation method that most preserved the bioactive compounds was microwave cooking + hot air drying, followed by autoclave cooking + hot air. Significance and novelty As a primitive species, emmer is a valuable raw material with a growing interest in its properties and products. This is the first study aimed to compare the effects of several production methods on the bioactive compounds and antioxidant activity of emmer bulgur.

Available technologies on improving the stability of polyphenols in food processing

“…Nevertheless, there are some studies in which different results using microwave cooking were observed. For example, Yilmaz (2019) reported that the microwave cooking showed the most positive effect on emmer bulgur instead of traditional and autoclave applications. However, Zhang and Hamauzu (2004) observed no difference between the conventional and microwave‐cooked broccoli.…”

The effects of genotypic variation in hulled wheat species and cooking methods on some quality parameters of bulgur

“…Moreover, E9 (955.40 µg GAE/g) and G38 (861.43 µg GAE/g) were the prominent with high TPC values in their own species. TPC values in this study were generally higher than the findings obtained from many studies (Caba et al, 2012), because the samples were efficiently extracted by a solvent acidified with HCl as stated by Yilmaz (2019). In addition to the extraction method, many factors including wheat variety with different genetic background, growing site, climatic conditions, and bulgur production methods can be effective on TPC (Caba et al, 2012;Ertas, 2017;Yilmaz, 2019).…”

“…and Koca (2017) and Yilmaz (2019) reported that microwave cooking for einkorn and autoclave cooking for emmer in addition to hot air drying were the best production methods to obtain high FA content.…”

Drying Behavior of Bulgur and Its Effect on Phytochemical Content

“…Thermal treatments, such as drying, have been reported to negatively affect the phytochemical content (polyphenol, flavonoid, and carotenoid) in bulgur, which causes its decrease [ 39 , 79 ]. It is important to mention that despite this decrease, no significant difference was found between the two drying methods.…”