New Quality Index Based on Dry Matter and Acidity Proposed for Hayward Kiwifruit
Researchers from various countries have proposed using dry matter at harvest as a worldwide quality index for Hayward kiwifruit, because it includes both soluble (sugars and acids) and insoluble (structural carbohydrates and starch) solids and doesn’t change during postharvest handling. Our consumer tests in 1999 and 2008 indicated that dry matter and ripe titratable acidity are related to in-store consumer acceptance of kiwifruit. In most California seasons, when ripe titratable acidity was less than 1.2%, only a dry matter greater than or equal to 15.1% was required for consumer acceptability. Our 6-year quality attribute survey of California kiwifruit at harvest and from cold storage demonstrated that dry matter and ripe soluble solids concentration were highly variable among vineyards and seasons, but ripe titratable acidity values varied more among seasons than between vineyards. Our results provide strong evidence that dry matter would be a reliable quality index candidate for California kiwifruit, especially if ripe titratable acidity were factored in.