The utilization of sulfur dioxide in the marketing of grapes

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The rapidly increasing volume of fresh grapes being shipped each year from California often taxes the resources of the railroads severely and during much of the season of 1922 resulted in serious congestion. The condition was similar, though less intense, in 1923. As a result, large quantities of grapes could not be shipped and were left to rot on the vines, while in those shipped, losses from spoiling were much increased by delays in delivery.

In consequence of these losses many inquiries were sent to the College of Agriculture as to methods of bettering these conditions either by improving the efficiency of the refrigerator cars now in use or by employing other modes of transportation.

Several possibilities suggested themselves, all based on the idea of delaying the deterioration of the grapes. This might make it possible to spread the shipments over a longer season, to utilize cars without refrigeration, and to increase the efficiency of refrigerator cars. The capacity of the railroads with their present equipment would thus be increased.

The causes of deterioration in transit or in storage are chiefly evaporation of water from the grapes and consequent shrivelling, and the activity of various micro-organisms causing decay. While on the vine, the grapes are freely exposed to dry air which retards the growth of the micro-organisms, and the water lost by transpiration is replaced by the vine. After removal from the vine, however, the grapes must be prevented from shrivelling by being kept in a relatively moist air to prevent evaporation. Moist air, however, fosters the growth and activity of micro-organisms.