Impact of thermal process on mushroom protein, free amino acids, and savory flavors contributed by MSG-like 5′-nucleotides and volatiles



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Mushroom substitution for animal protein would create positive environment and health benefits; however, few studies exist regarding cooking approach and mushroom type impact on protein quality and savory flavors. This thesis study aimed to investigate thermal processing impacts on 1) mushroom protein amino acids and on 2) mushroom free amino acids, nucleotides, and volatile compounds. For aim 1 method development, seven mushroom powder hydrolysates (0–96 hr) were analyzed via EZ:Faast derivatization with gas chromatography-mass spectrometry (GC-MS) quantification. Thermal processing impact was ascertained by comparing single interval (24 hr) hydrolysate protein amino acids for cooked mushrooms using the same method. A viable hydrolysis procedure and correction values for Val and Ile resulted. Cooking method and mushroom type interactions were observed for most amino acids. Additionally, all total and individual protein amino acids decreased upon cooking (excluding Met). The second most limiting essential amino acid in both mushroom types, His, did not significantly differ between grilling and roasting cooking methods. Comparing grilling and roasting in shiitake and portabella, there were no significant differences. For aim 2, GC-MS and high-performance liquid chromatography– ultraviolet detection (HPLC–UV) were used to quantify 22 free amino acids, five 5′-nulceotides, and 125 volatiles. Glu (umami taste) was the most dominant amino acid in both raw and cooked white and crimini, while Asp (umami taste) content was much lower. These mushrooms also contained all essential amino acids and other sweet- and bitter-related amino acids. 5′-GMP (umami taste) was the most dominant of the 5′-nucleotides, followed by 5′-CMP and 5′-UMP (tasteless). Cooking significantly decreased free amino acids by 7-14 times, 5′-nucleotides by 3-8 times; whereas cooking increased most volatiles by number and quantity (20-68 times). Variety difference was minimal for free amino acids and 5′-nucleotides, but it was more obvious for volatiles. This study’s results provide great value for future researchers and the food industry alike.



Health Sciences, Nutrition, Chemistry, General