SINCLAIR INTERNAL QUALITY FIRMNESS TESTER AS A NON-DESTRUCTIVE HARVEST INDEXING AND QUALITY SORTING TOOL FOR ‘TRIUMPH’ PERSIMMON FRUIT

Abstract

In persimmon, Magness and Taylor test is used to assess fruit firmness. However, its destructive nature necessitates the use of few samples which increase chances of error. Poor quality fruits are, therefore, likely to be shipped to consumers. In this study, the potential of a non-destructive Sinclair Internal Quality firmness tester (SIQFT), as an alternative to Magness and Taylor test was investigated. ‘Triumph’ persimmon fruits were harvested from six farms in Western Cape, South Africa, in two consecutive fruiting seasons. Fruits from each farm were sorted into 4 colour groups using persimmon fruit colour chart.  Four replicates of 30 fruits per colour group were collected and one third of the fruit per replicate were evaluated for fruit firmness, Sinclair internal quality firmness index (SIQFI), total soluble solids (TSS), fruit colour and soft fruit percentage at harvest, after storage and after shelf-life. Fruit firmness was measured using Magness and Taylor fruit texture analyzer (MT-FTA) and SIQFI was measured using SIQFT. TSS and soft fruit percentage were measured conventionally. Fruit firmness and SIQFI were correlated using linear regression analysis and Pearson correlation procedure was used to correlate SIQFI and other quality attributes. There was a linear relationship between SIQFT and MT-FTA, R² = 0.8, 0.7 and 0.8, at harvest, after storage and after shelf-life, for 2013 season fruit and 0.8, respectively, at harvest, after storage and after shelf-life, for 2014 season fruit. The correlations between SIQFI and TSS, SIQFI and soft fruit percentage and SIQFI and fruit colour, were significant in both 2013 and 2014 season fruits. It could be concluded that SIQFT correlates with MT-FTA and other important fruit quality attributes. SIQFT can, therefore, be used as a non-destructive firmness testing tool for persimmon fruit.