Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 28, 1998
Publication Date: N/A
Interpretive Summary: Apples are unsalable when they have become soft or have lost their firmness. Calcium treatment is helpful in maintaining firmness, but treatment methods are restricted or not always successful. To develop an improved treatment method, a better understanding is needed of how the added calcium interacts with cellular components, specifically the cell membrane, to retain firmness. Analysis of the cellular membranes of calcium treated apple fruits indicated that various membrane components were conserved by the calcium treatment, which contributed to maintenance of firmness. This information is helpful to scientists who seek to understand the role of calcium in maintaining cellular integrity, and will help to develop methods to treat apples with calcium so that consumers will have good quality fruits.
Net changes in membrane lipid concentrations in outer cortical tissue of mature calcium- infiltrated 'Golden Delicious' apples were evaluated. Fruit were pressure infiltrated at harvest with water or calcium containing solutions. Calcium infiltration resulted in greater retention of fruit firmness following 6 months storage at 0 degrees C plus 7 days at 20 degrees C. During cold storage, total phospholipid and acylated steryl glycoside concentrations increased in calcium-infiltrated fruit, but decreased in water-infiltrated fruit. The total phospholipid concentration was greatest in fruit infiltrated with 4 percent calcium chloride 7 days after transfer to 20 degree C. Free sterol and steryl glycoside concentrations in fruit stored 6 months at 0 degree C increased with increasing infiltrated calcium concentration. Greater conservation of specific membrane lipid components in calcium-infiltrated apple fruit during and after low temperature storage may contribute to the beneficial effects of calcium infiltration in maintaining apple fruit quality.