Abstract:One week after the 'Sweet Charlie' strawberry trees produced flowers, they were sprayed with water or CPPU at either of the four concentrations (2.5, 5.0, 10, 20 mg/L). The contents of soluble solids, total acid, free amino acids, and tannins of the resultant strawberry fruits were measured. The taste indicators such as sourness, sweetness, bitterness, umaminess, saltiness, astringency, and aftertaste of bitterness and astringency were analyzed by the electronic tongue technique, to evaluate the effect of CPPU and its concentration on the flavor, nutritional quality and taste of strawberry, as well as the advantages of using electronic tongue to investigate the effect of CPPU on the taste of strawberries. The obtained results showed that the use of CPPU could increase the content of soluble solids, reduce the total acid content, increase the solid-to-acid ratio, and reduce the number of species and total amount of free amino acids in strawberry fruits. Low concentrations (2.5 or 5.0 mg/L) of CPPU could reduce the tannin content of strawberries, whilst high concentrations (10 or 20 mg/L) could increase significantly this content. The results of the electronic tongue analysis, the CPPU treatment at low concentrations could increase the sweetness and reduce sourness, with the corresponding reduction in the saltiness and umaminess along with their highly correlated bitterness (correlation coefficient: 0.99). There were positive correlations between the total amount of free amino acids and umaminess, the tannin content and astringency, the total acid content and sourness, the solid-to-acid ratio and sweetness. The CPPU treatments at low concentrations had a positive impact on the sweetness and sourness and associated flavor composition of strawberry. However, a CPPU treatment, regardless of its concentration, had a negative impact on salty and umami tastes and associated flavor composition.
