Effect of amino acid composition on the taste of 'Hakuho' peaches (Prunus persica Batsch) grown under different fertilizer levels.

摘要

The effect of amino acids on the taste of peach fruits was investigated by sensory evaluation tests. Fruits were harvested from Hakuho trees that were grown at complete liquid fertilizer rates of at 40 (L), 80 (M), and 160 ppm N (H). Major amino acids analysed were asparagine (ASN), serine (SER), threonine (THR), arginine (ARG), and aspartic acid (ASP), which accumulated at significantly higher concentrations with increased fertilizer rates. Sensory evaluations showed that juice from the H treatment fruits was more sour and had a bitter taste, whereas that from the L treatment was equally sweet as the juice from the M treatment; the overall evaluation gave the highest mark to the M treatment. After removing amino acids from juice using ion exchange resins, the major amino acids were added again individually or cumulatively to the original concentrations of each treatment juice. SER, ARG, and ASN increased sweetness, whereas ASP increased sourness in each case. Such amino acids improved "umami" (deliciousness or depth of the taste) and overall taste at the concentrations of those in the M treatment juice but they increased bitterness and, thereby, lowered the overall evaluation of the H treatment juice. These results indicate that amino acids improve the taste of peach fruits, but excessively high levels of ASN and ARG lower the sensory quality.