OPTIMIZATION OF UMAMI COMPOUNDS EXTRACTION FROM SHIITAKE (Lentinula edodes) BYPRODUCTS

Mushrooms are appreciated worldwide for their distinct flavor. Among their components, umami compounds (free amino acids (FAA) and 5’-nucleotides) are capable of acting as flavor enhancers. Aiming to use shiitake byproducts as natural flavor enhancer in foods, this study optimized the umami compounds extraction from shiitake byproducts and quantified FAA of the extracts obtained under optimal condition. For optimizing the aqueous extraction of umami compounds, response surface methodology (RSM) was performed, applying a rotational central composite design, in which explanatory variables were: solute:solvent ratio (1:20 to 1:70; w:v) and heating bath temperature (24 to 70°C). The extraction time was 30 minutes for all assays. The dependent variable was umami taste intensity in the extracts, which was evaluated through sensory analysis with trained panelists. The panelists were trained to use the unstructured linear intensity scale of 90 mm length and were selected regarding their discriminative (p<0.30) and reproducibility (p>0.05) capacities, and consensus with the panel (Pearson’s r >0.70). For comparing the influence of dehydration process on FAA, shiitake stipes were conventionally dehydrated (C) and lyophilized (L), and their umami compounds extracted under optimized conditions. FAA were measured through HPLC-F. The RSM results showed that temperature did not have significant effect on umami taste intensity, while ratio did. The adjusted mathematical model presented R²=0.89, it was significant and showed no lack of fit. The extract from sample C presented more complex FAA composition compared to the extract from sample L. Among the monosodium glutamate-like FAA, 0.37 mg/g aspartic acid and 2.53 mg/g glutamic acid were found in sample C, while sample L had just traces of these FAA. Thus, to obtain an extract with high umami taste intensity, the stipes should be conventionally dehydrated, and umami compounds extracted using a 1:20 (w:v) ratio for 30 minutes, regardless the applied temperature.