14A-12

V. M. MATTA¹, L. M. C. Cabral, R. B. Rodrigues³, R. H. Moretti, and H. C. Menezes. (1) Food Engineering, Embrapa Food Technology, Av. das Americas, 29501 - Guaratiba, Rio de Janeiro, 23020-470, Brazil, (2) State University of Campinas, Brazil

The acerola and camu-camu are tropical fruits characterized by their high ascorbic acid contents which makes their consumption very attractive. To process acerola and camu-camu juices, membrane technology is indicated because of its nonthermal characteristic. However, one of the important parameters of such technology is the rheological behavior of the juices, which is very different for these fruits.

The objective of this research was to study the behavior of acerola and camu-camu juices during clarification by ultrafiltration for these 2 different raw materials.

Ultrafiltration was carried out in a Protosep IV unit from Koch Membrane System, consisting of 3 tubular membranes. The permeate flow rate was determined during the process as a function of the filtration time. The feed and permeate juices were analyzed for their main physical-chemical characteristics.

The vitamin C loss due to the clarification process was 5.7% for the acerola juice after 2-h processing while for the camu-camu the loss was 11% after 4-h processing. The main difference observed between the 2 fruit juices was the process behavior due to their rheological characteristics. The original viscosities of the juices were 22 mPa.s for acerola and 1.2 mPa.s for camu-camu. While camu-camu juice presented a Newtonian fluid behavior, acerola juice was pseudoplastic and its higher viscosity caused an increase in the retentate viscosity, which reduced the permeate flow rate and the processing time. The mean permeate flow rate for the camu-camu process of 32.7 L/hm2 was about 37% higher than that of the acerola process, 20.8 L/hm2.

It was observed that it is necessary to optimize the process conditions for different fruits and that the clarified juices obtained presented high quality, which indicates their use as they are or as a base for blends, soft drinks, sport drinks, jellies, infant foods, and many others.