The wax bloom on blueberry: Application of luster sensor technology to assess glossiness and the effect of polishing as a fruit quality parameter

• Main Authors: Patiwit Loypimai, Sudpiti Paewboonsom, Lutz Damerow, Michael M. Blanke
• Format: Article
• Language: English
• Published: Julius Kühn-Institut 2017-05-01
• Series: Journal of Applied Botany and Food Quality
• Subjects: Fruit quality; non-invasive detection; sensor technology; wax
• Online Access: https://ojs.openagrar.de/index.php/JABFQ/article/view/7336

The wax bloom of the fruit is responsible for the visible quality of blueberries. This study aimed to investigate a new technology using the effect of polishing on micromorphology, wax content and weight loss of blueberries. Luster sensor (type CZ-H72, Keyence, Japan) technology was used to assess glossiness of polished blueberries compared with berries with a natural (unpolished) wax layer during 9 days after harvest. Blueberries were rubbed twice by hand within a soft microfibre tissue to obtain polished fruit. Unpolished blueberries contained ca. 120 μg wax cm-2, which was reduced by ca. 22% to ca. 95 μg cm-2 by polishing. This reduction was associated with an increase in luster levels from ca. 65 to 80 a.u.. Weight loss was larger from polished than from unpolished blueberries with a concomitant 40% increase in luster levels from 60 to 85 a.u. in polished fruit. Luster levels sharply decreased from 85 a.u. in the first 5 days after harvest and then leveled off to remain almost constant at ca. 20 a.u. with significantly larger values for polished blueberries of ca. 30 a.u. with a larger magnitude of glossiness. Overall, luster sensor technology may offer a new effective, affordable, possibly portable, non-destructive technique to assess glossiness or other surface features in real time for classifying not only blueberry, but also other waxy fruit such as aubergine/eggplant, plum, Juniperus, blue grape berry etc..