Effects of roasting temperature and duration on fatty acid composition, phenolic composition, Maillard reaction degree and antioxidant attribute of almond (Prunus dulcis) kernel

• Published in: Food chemistry Vol. 190; pp. 520 - 528
• Main Authors: Lin, Jau-Tien, Liu, Shih-Chun, Hu, Chao-Chin, Shyu, Yung-Shin, Hsu, Chia-Ying, Yang, Deng-Jye
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.01.2016
• Subjects: Almond kernel; Antioxidant; Antioxidants - pharmacology; Fatty acid; Fatty Acids - chemistry; Flavonoids; Hot Temperature; Maillard Reaction; Non-enzymatic browning index; Oxidation-Reduction; Phenolic component; Phenols - analysis; Plant Extracts - chemistry; Plant Oils - chemistry; Prunus dulcis - chemistry; Non-enzymatic browning index; Almond kernel; Antioxidant; Phenolic component; Fatty acid
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2015.06.004

•The change of fatty acid profile of almond kernel oils during roasting is revealed.•Roasting temperature and duration affect phenolic profile in almond kernels.•Antioxidant effects of roasted almond kernels correlated well with phenolic contents.•Browning indices of almond kernels increased with roasting temperature and duration.•Maillard reaction products contribute to antioxidant effects of roasted almond kernels. Roasting treatment increased levels of unsaturated fatty acids (linoleic, oleic and elaidic acids) as well as saturated fatty acids (palmitic and stearic acids) in almond (Prunus dulcis) kernel oils with temperature (150 or 180°C) and duration (5, 10 or 20min). Nonetheless, higher temperature (200°C) and longer duration (10 or 20min) roasting might result in breakdown of fatty acids especially for unsaturated fatty acids. Phenolic components (total phenols, flavonoids, condensed tannins and phenolic acids) of almond kernels substantially lost in the initial phase; afterward these components gradually increased with roasting temperature and duration. Similar results also observed for their antioxidant activities (scavenging DPPH and ABTS+ radicals and ferric reducing power). The changes of phenolic acid and flavonoid compositions were also determined by HPLC. Maillard reaction products (estimated with non-enzymatic browning index) also increased with roasting temperature and duration; they might also contribute to enhancing the antioxidant attributes.