G1600 Freeze Concentration of Fruit Juices

This publication describes research conducted to examine the feasibility of freeze concentration with small-scale, simple equipment; and research results on juice extraction and concentration from fruit held in frozen storage. When Grandmother made jelly the wonderful aroma of cooking fruit filled the house. That wonderful aroma was the delicate fruit flavors being evaporated and lost from the jelly. When volatile flavors are retained food has a much better flavor. Freeze concentration of fruit juices is a method of removing water from juices without heating and changing juice flavor. Freeze concentration is effective because a solute in solution has a lower melting point than pure ice, and can be separated from the water component (ice) as the temperature approaches the melting point of pure ice. To easily confirm this, remove a plastic jug of cider from the freezer, invert the jug in a suitable container, place the jug and container in a refrigerator and allow it to approach thawing temperature. Concentrated apple juice will collect in the container, leaving ice in the jug. Freeze concentration has many practical applications in food processing. It is effective in adding fruit solids to wine musts; in reducing the amount of cooking necessary to produce jellies, jams and, preserves; and in improving flavor and characteristics in many food products. Freeze concentration has been practiced in the food industry for over 30 years, but the equipment is too expensive for most small enterprises