S23 - Session O6 - Blueberry mealiness: An influence of varietal texture differences

Authors: Angelo Castro *, Maarten Hertog, Clare Kyomugasho, Bart Nicolai

Blueberry's growing popularity as a healthy snack is in jeopardy because of concerning reports of mealiness, a texture abnormality characterized by a soft, dry, crumbly or coarse mouthfeel. The cause of its development is unknown and there are limited methods for its detection. It is therefore the aim of the study to develop a reliable mealiness detection method specific for blueberry, identify the cause of its occurrence and elucidate the biochemistry behind its development. Blueberry varieties (7) belonging to different season bearing classes (early, mid and late) and picking sequence (early and late) were stored for 5 weeks at 0°C, 85-90% RH. Freshly harvested berries and those cool-stored for one, three and five weeks were then moved to 18°C for shelf-life monitoring until the limit of marketability was reached. A texture analyzer method was developed to measure firmness and juiciness simultaneously and used to evaluate blueberries. Juiciness, or the lack thereof, was used as a preliminary mealiness indicator. No mealiness developed during storage and shelf-life for both early- and late-picked berries as indicated by minimal changes in juiciness and mechanical properties. On the other hand, clear varietal differences were observed at harvest. These results were corroborated by observed variability in cell wall enzyme activities (polygalacturonase, pectin methyl esterase, β-galactosidase and α-arabinofuranosidase) among varieties. The range in blueberry varieties on offer in supermarkets relative to their seasonality tentatively explains these reports of unfavorable texture (mealiness). Presently, cell wall fractions are being analysed to further explain these varietal texture differences.