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Maximizing Shelf Life
The shelf life of unpasteurized cider can be greatly increased by quickly chilling freshly pressed cider to a temperature of 35oF and adding either potassium sorbate or sodium benzoate. Maximum concentrations of chemical preservatives allowed in Pennsylvania cider are 0.1 percent of sodium benzoate or benzoic acid (1 ounce per 8 gallons) and 0.05 percent sorbic acid (1/2 ounce per 8 gallons). If the initial microbial cell count in cider is low and the cider is stored consistently at 32 to 36°F, a preservative concentration as low as 0.05 percent may be adequate.
Potassium sorbate is relatively tasteless, but it is more costly than sodium benzoate. Some consumers prefer potassium sorbate because they dislike the slightly bitter taste and presence of sodium in sodium benzoate. If a preservative is used, it should be added immediately after pressing the cider. For a 0.1 percent concentration of potassium sorbate, add 1 gallon of a 25 percent stock solution to each tank of 250 gallons, or 1/2 ounce per gallon of cider. Because it is only slightly soluble, the sorbate solution should be added slowly and stirred vigorously in cider. For a 0.1 percent concentration of sodium benzoate, add 1 ounce of a concentrated solution to 8 gallons (or 1 quart to 250 gallons) of cider.
The shelf life of cider may be increased by heat-pasteurization. However, unless the cider is heated rapidly and held for 10 to 15 seconds at 160°F, then cooled rapidly to 35°F, the cider will have a slightly cooked flavor. Among the various systems for pasteurizing cider, a continuous plate, temperature, and flow-controlled pasteurizer (similar to those used for pasteurizing milk) is the most efficient, easily controlled system and results in the best-quality cider. Canning is accomplished by heating cider to 195°F in the same type of pasteurizing system, then filling and sealing containers immediately and waiting five minutes before cooling the metal or glass containers. Fresh-pressed cider preserved by freezing and stored at 0°F retains the most natural aroma and flavor. In fact, frozen cider retains its high quality for several years if packaged and stored properly. The relative quality and shelf life of unpasteurized versus preserved cider stored at several temperatures are compared in Table 7-2.
Shorter shelf life should be expected when:
• lower-quality fresh apples are used
• fresh apples are not properly sorted or washed
• cider is in contact with wood or metals other than stainless steel
• freshly pressed cider is not cooled rapidly
• equipment and facilities are not properly cleaned and sanitized daily when in use
• the temperature of refrigerated cider is allowed to fluctuate by more than 5°F