Blueberry Cell Wall Polysaccharide Composition of Three Distinct Fruit Firmness Phenotypes

Abstract

Blueberry (Vaccinium corymbosum) cultivars vary in firmness, and these phenotypic differences may be associated with peel and pulp cell wall polysaccharides. Three blueberry cultivars of distinctive texture phenotypes, Indigocrisp (crisp), Emerald (firm, industry standard), and Jewel (soft), were evaluated for cell wall polysaccharide composition. Alcohol-insoluble residues (AIRs) from both peel and pulp were reduced, methylated, hydrolyzed, acetylated, and quantified using gas chromatography–mass spectrometry (GC-MS). Monosaccharide composition (μg·mg–1 AIR) differed among cultivars, with “Indigocrisp” pulp highest in glucuronic acid (22.23), “Emerald” pulp highest in glucose (106.31), and “Jewel” peel highest in arabinose (38.73) and mannose (11.88). Forty-five cell wall polysaccharide linkages were identified, and specific linkages were associated with blueberry peel and pulp among the texture phenotypes. Polysaccharide classifications were then estimated from the 45 cell wall polysaccharide linkages. “Indigocrisp” and “Emerald” pulp were highest in arabinan and type II arabinogalactan, which are less susceptible to depolymerization. “Indigocrisp” pulp had a greater abundance of heteromannan, xyloglucan, and cellulose, while “Jewel” was highest in rhamnogalacturonan I, which typically depolymerizes first. The greater abundances of arabinan and type II arabinogalactan in the pulp of the firm and crisp cultivars likely contribute to the texture characteristics of these phenotypes.