Aronia mitschurinii is a crop obtained by crossbreeding 25% of Mountain Ash with 75% of Aronia Melanocarpa. Aronia has been known as a fruit having highest known antioxidant contents, making it a superfood. Recently we have shown that elderberries, mulberries and hascaps have anthocyanin content similar to aronia. We found for aronia that both anthocyanins and brix reach peaks over the ripening period, yet those peaks occur 2.5-3 weeks apart. Harvesting at the peak of anthocyanins is important for nutraceutical applications, while for food applications harvesting at the peak of brix is required. However, the color is the same at both peaks, presenting a challenge for farmers to decide on harvesting dates. Current laboratory methods for brix are relatively simple, while measuring anthocyanins requires expensive lab equipment that is out of reach for farmers. This creates a need for a cheap, simple, portable testing kit to test both brix and anthocyanins in the field. Anthocyanins in berries are in glucoside form, with cyanidin-3-glucoside (C-3Glu) being the major one. Glucoside bonds can be hydrolyzed at acidic pH. We have observed that at neutral pH, the measurement made with glucometer gives readings proportional to the brix content observed with refractometer, where as at acidic pH, when glucoside bonds are hydrolyzed, glucometer measures both soluble glucose and the hydrolyzed glucoside from C-3Glu, giving readings proportional to anthocyanin content measured by UV/Vis. The glucometer can only read values in a certain range, requiring to dilute juice from smashed berries with a buffer.  Here we present the comparison of UV/Vis and refractometer measurements of aronia juice over the entire ripening period, from the time berries are green and until they are over-ripened, in comparison with glucometer reads of same samples diluted by buffers of pH 7 and pH 3.5. As well, prototypes of cartridge for dilution of aronia samples in the field and comparison of these prototypes with manual sample preparation will be presented.

Probing the ripeness of berries rich by anthocyanin for food and nutraceutical markets with ripeness gauge

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