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| Author(s): |
Vanessa Aparecida Marcolino
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Campinas, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Faculdade de Engenharia de Alimentos |
| Defense date: | 2003-02-27 |
| Examining board members: |
Pilar Rodriguez de Massaguer;
Glaucia Maria Falcão de Aragão;
Hilary Castle de Menezes
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| Advisor: | Pilar Rodriguez de Massaguer |
| Abstract | |
In Brazil the consuption of ready to drink pasteurized grape juice has increased in the last few years. In 2001, the national consumption was 11 million liters, however, in the first nine months of 2002, this number exceeded 17 million liters (Tetra Pak, 2002). The aim of this study was to quantify the incidence of heatresistant and non heat-resistant molds in the production line of juice formulated from Ceiber and Concordia grapes (pH: 3,0 and 14°Brix). The analysis was carried out from the raw material up to the final product, and afier 3 months of shelf-life to obtain the microbiological security of the product. Nine (9) points from the processing line were sampled for each batch. Six (6) production batches were analyzed from January 2ih, 2002 to March 3rd, 2002. The method of Beuchat and Pitt (1992) was used to quantify the heatresistant molds with the modifications suggested by Baglioni (1998). Common molds and yeast were anayzed according to the Compendium of Methods for the Microbiplogical Examination of Foods (A.P.H.A.) (1992), and Splittstoesser et ai (1993). Twenty-five (25) mold strains were isolated from the 6 batches, of which 24 showed completely different bahavior. Heat-resistance was confirmed in ali of the 24 strains, afier selective heat shocks. Batches 2 and 3 showed greater contamination with heat-resistant molds, showing 4,8 and 3,5 spores/100ml respectively in the raw material, however in general the contamination levei with heat-resistant strains was low, normally less than 5 spores/100ml. Batch 1 was responsible for the greatest variety of strains, 48% of the total, equivalent to 12 different molds. The highest incidence of yeasts was observed in the raw material, with levels of up to 106 CFU/ml. To confirm the greater heat-resistance of older spores when compared with younger spores, the heat-resistance test was carried out with 1 month and 3 months old spores. Ali the iso/ates, of both ages, were submitted to programmed heat shocks from 85°C/15 min up to 115°C/15 mino The most heat-resistant 1 month old mold spore survived 100°C/55 min and was identified as Neosartorya fischeri with D95°c= 1,66 min and Z= 11,98° C. The most heat-resistant 3 months old mold survived 11 0°C/1 Omin and was also identified as Neosartorya fischeri with D95°c= 1,96 min e Z= 16,29° C. The kinects parameters were realized using Alderton & Snell (1970) methodology becouse both molds present non logaritmical behavior. The process used was able to eliminate the mold contamination and its presence was not detected in the final product or in the final product after 3 months of shelf life. Nevertheless, molds like Neosartorya fischeri may survive the juice pasteurization process of 90-92°C/30 seconds commonly used in industry, because of the high heat-resistance of this mold (AU) | |