APPLICATION OF VANILLIN AND GERANIOL AS NON-THERMAL TECHNOLOGIES IN STRAWBERRY JUICE PRESERVATION

TOMADONI, BÁRBARA; CASSANI, LUCÍA; MOREIRA, MARÍA DEL ROSARIO; PONCE, ALEJANDRA

Concordia

Congreso; International Conference on Food Innovation; 2014

Universidad Nacional de Entre Ríos y Universidad Politécnica de Valencia

With the increasing demand of fresh-like and nutritious foods, unpasteurized juices have become a rapidly growing segment of the food industry, with similar or equivalent quality properties to the natural fresh products. However, fresh fruit juices are highly perishable, susceptible to spoilage and deterioration, due to the activity of enzymes, and the exposure to oxygen and microorganisms. Thermal processing technologies used for inactivating the microorganisms in fruit juices, seriously affect their nutritional and sensory quality. Therefore, there has been a growing interest in the search of novel technologies that avoid the application of thermal treatments. The objective of the present work was to evaluate the antimicrobial effects of two bioactive compounds in strawberry juice: vanillin (Van) and geraniol (Ger). First, the Minimum Inhibitory Concentration (MIC) was evaluated using Listeria monocytogenes, Staphylococcus aureus, Escherichia coli and Pseudomona aeruginosa as indicators. Once the MIC was obtained, the bioactive compounds were applied in strawberry juice at 1 MIC and 2 MIC (Van1MIC, Van2MIC, Ger1MIC, Ger2MIC). Two controls were used: an untreated sample and a sample thermally treated at 90 °C for 60 s (TT90°C60s). Samples were storage at 5 °C during 13 days. At days 0, 3, 7, 10 and 13, mesophilic bacteria (MES, 34 ºC, 24 h), psychrophilic (PSY, 7 °C, 7 d) and yeast and moulds counts (YM, 25 ºC, 5 d) were evaluated. The different microbial populations showed similar patterns of behavior towards the bioactive compounds applied. At day 0, Van1MIC and Van2MIC had no significant difference from untreated sample, but during refrigerated storage reduced significantly the microbial counts from 5 log CFU/mL to approximately 3 log. Samples Ger2MIC and TT90ºC60s showed a microbial reduction of 3 log during the first week of refrigerated storage. However, from day 7 the sample TT90ºC60s showed an increase in microbial counts, reaching values of 5 log CFU/mL at the end of storage. In conclusion, Ger and Van were more effective in reducing and maintaining the native microflora of strawberry juice than a traditional thermal treatment; they are both GRAS and could easily be applied in the food industry. Among the bioactive compounds, Ger2MIC was the most effective. However, further studies should be made in order to evaluate the sensory and nutritional quality of unpasteurized juices treated with Ger and Van.