Texture variation in apricot: Intra-fruit heterogeneity, impact of thinning and relation with the texture after cooking

Abstract

The rapid texture loss of apricot fruit during storage and transformation is a limiting factor for its commercialisation and use. Apricot flesh exhibits different tissue zones which differ in texture. To better understand texture in apricot fruit, we have studied (i) the intra-fruit heterogeneity of texture measured by puncture test (tissue firmness) (ii) the effect of thinning on whole fruit firmness (global firmness), measured by compression, and on tissue firmness and (iii) the evolution of texture upon steam cooking, on apricots of contrasted texture. Nine tissue zones were defined in fresh apricot fruits in order to study differences in texture from the peduncle to the pistil zones and from the external to the internal tissue. In the nine apricot varieties used, tissue firmness decreased gradually from the external to the internal tissue. However, from the peduncle to the pistil zone, the variation of texture seemed to be variety-dependent. Overall the textures measured for the nine tissue zones were highly correlated, indicative of the major differentiation between soft and firm fruits. However distinct heterogeneity patterns could be observed on axes 2 and 3 of a principal component analysis carried out on the textures of the nine zones. The effect of thinning on fruit firmness appeared variety-dependent. Tissue firmness of the raw apricots assessed by penetrometry explained about two-thirds of the variability of firmness of cooked apricots, versus only 40% for the compression test. High correlations between texture after cooking and prior to cooking were found for four (external equatorial, external pistil, median equatorial and median pistil) out of the nine tissue zones.