The procedure for citrus section production envisages fruit peeling, fraction separation and carpellary membrane removal. Using traditional methods, steam, boiling water and lye solution are applied (Braddock, 1999). After separation from the peel, membranes can be removed with a chemical treatment in a hydrochloridic acid diluted solution (0.6-0.7 per cent) for 40 seconds at 30—35 °C, followed by quick washing under water, passage in a sodium hydroxide diluted solution (0.4-0.5 per cent) for 15 seconds at 35 °C and a final rinsing. This required labour-intensive process and is a drawback. To reduce production costs and facilitate membrane and peel removal, alternative systems, based on pectolitic enzymes, have been proposed (Janser, 1996). First, citrus fruits undergo a piercing treatment which allows dipping into the superficial flavedo and penetration of the enzymatic solution. The pectolitic treatment is carried out under vacuum conditions, at determined pH, temperature and duration, depending on the enzymatic activity; peel is manually removed under a water jet. The following step is the separation from the carpellary membranes. This is obtained with a treatment similar to the previous one, and the resulting sections are cleaned in water. Sections can be packed and commercialized as fresh, frozen, canned or dry products (without a covering liquid). When refrigerated at 1-2 °C, the fractions keep their organoleptical features for about three weeks (Baker and Gromann, 1995). Considerable liquid could be discharged during shelf-life. The drawback can be avoided by covering the segments with a wax micro-emulsion (Baker and Hagenmaier, 1997).
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