Assessment and Partial Characterization of Candidate Genes in Dihydrochalcone and Arbutin Biosynthesis in an Apple-Pear Hybrid by De Novo Transcriptome Assembly.

Apples (Malus × domestica Borkh.) and pears (Pyrus communis L.) are valuable crops closely related within the Rosaceae family with reported nutraceutical properties derived from secondary metabolites including phloridzin and arbutin, which are distinctive phenolic metabolites characterizing apples and pears, respectively. Here, we generated a de novo transcriptome assembly of an intergeneric hybrid between apple and pear, accumulating intermediate levels of phloridzin and arbutin. Combining RNA-seq, in silico functional annotation prediction, targeted gene expression analysis, and expression-metabolite correlations, we identified candidate genes for functional characterization, resulting in the identification of active arbutin synthases in the hybrid and parental genotypes. Despite exhibiting an active arbutin synthase in vitro, the natural lack of arbutin in apples is reasoned by the absence of the substrate and broad substrate specificity. Altogether, our study serves as the basis for future assessment of potential physiological roles of identified genes by genome editing of hybrids and pears.

Effect of pear apple and date fibres incorporation on the physico-chemical, sensory, nutritional characteristics and the acceptability of cereal bars.

Cereal bars are nutritious food composed of several ingredients including dry raw and agglutinative ingredients. The objective of this study was to evaluate the effect of pear apple and date fibres, from cooked fruit co-product, addition on the physico-chemical textural and sensory properties of cereal bars. First, five formulations containing an amount of 10% of co-products and commercial fibre, used as a reference, were elaborated and their physico-chemical composition was determined. Second, to determine the acceptability of consumer, apple fibre co-products were added (6, 10 and 14%). Products were evaluated for their texture using a texturometer and sensory characteristics using an acceptance test. Results showed that physico-chemical composition of cereal bars elaborated with co-products was slightly different compared to those elaborated with commercial fibre. All bars have low water activity levels (∼0.470) and interesting energy (300 kcal/100 g bar). External appearance revealed a darker colour (L*:∼42/a*:∼8/b*:∼20). There were no significant differences (P > 0.05) in texture values (hardness: 40.8 N; cohesiveness: 0.34; springiness: 0.60; chewiness: 8.30 N) between cereal bars prepared with pear co-product and wheat bran. Acceptance test confirms the formulation used for cereals bars and showed that incorporation of 10% of co-product produced cereal bars with the highest acceptability. Sensory characteristics revealed that appearance is the limiting factor for consumer acceptability, essentially for cereal bars containing pear co-product. Apple, pear and date co-products could be used successfully as a food ingredient to develop new formulations of cereal bars.