Effect of Delay in Harvesting on the Composition of grapes

¹ California Grape Products Corp., Delano, California
² Camp Jeppi Bradshaw Farms, Bakersfield, California

Actual field tests have been carried out to demonstrate whether there is a real advantage from a monetary standpoint, when harvesting of grapes is postponed after maturity has been reached. The tests carried out on two separate years with climatic conditions widely different extend the usefulness of the results. Rows of vineyards were laid out at random and the grapes picked at weekly intervals from 25 percent of each variety. The weights were noted and an analysis run on each batch, comprising Balling, total acid and pH. The heat effect on the grapes is strikingly demonstrated by the more rapid changes observed in the 1954 crop as compared to 1955. Loss of water is a significant factor in the losses registered. A small portion of the weight loss may be attributed to the disappearance of the acids along with other constituents too small to measure. With each succeeding week the total sugar units delivered after the first picking are reduced in the large majority of cases. The pH was used as a criterion of maturity. The study demonstrated that no advantages are gained by retaining grapes unduly on the vines, after maximum weight and maturity have been reached.