ABSTRACT
Volatile fractions of fruit juices have the distinctive aroma and flavor of fruits and are popularly known as fruit extracts. Fruit extracts find uses in enhancing fruit flavors in fruit juices or as substitutes for fruit juice in fruit drinks and beverages. Fruit juice concentrates and volatile fruit extracts are being used increasingly as a base to which other ingredients are added. There has been a phenomenal growth in the consumer demand for natural fruit flavors, and their addition to end products, such as soft drinks, confectioneries, soaps, and toiletries. An important aspect of the commercial production of fruit juices is the method of processing fruit juice for separation of volatile components. For applications of flavor from citrus fruits, the volatile components present in the fruit juice are separated into oil-phase volatiles and water-phase volatiles. For most other fruits, volatile components are recovered only from concentrated juice and thus belong only to the water-phase volatiles. During the heat treatment and concentration processes, the fruit juices often undergo change in flavor profiles. In the manufacture of grape juice, it was indicated by Ohta et al. (1994) that 99.3% of the flavor of grape juice changed during its processing. For example, low-boiling volatile components, such as 2-methyl-3-buten-2-ol and ethyl crotonate were lost upon processing, as indicated by the head space analysis of fresh grape flavor. Even the high-boiling component, methyl anthranilate, was reduced to half after the concentration process. It is thus apparent that efforts should be made to recover the fruity flavor from juices prior to or during heating and concentration. A typical schematic representation of the fruit essence (extract) recovery process is shown in Figure 5.1. In addition to recovering fruity flavor from fruit juices, other related processes of significant importance include deterpenation, dealcoholization, enzyme deactivation, and stabilization of fruit juices. Different processes will be discussed for both citrus and noncitrus fruit extracts in the following sections.
