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Sterilization and aseptic packaging of soymilk treated by ultra high pressure homogenization

Poliseli-Scopel, Fábio Henrique, Hernández-Herrero, Manuela, Guamis, Buenaventura, Ferragut, Victoria
Innovative food science & emerging technologies 2014 v.22 pp. 81-88
Bacillus cereus, UHT treatment, aerobes, ambient temperature, aseptic packaging, bacteria, beverages, consumer demand, containers, food industry, homogenization, microbial growth, nutritive value, off flavors, oxidation, paperboard, particle size distribution, sensory evaluation, soymilk, spores, volatile compounds
Ultra high pressure homogenization (UHPH) was applied on soymilk to produce an aseptically packaged beverage. UHPH-treated soymilk (300MPa, 80°C inlet temperature and 144°C/0.7s at the homogenization valve) was compared with samples treated by ultra high temperature (UHT) at 142°C for 6s. After treatment, soymilk samples were aseptically packaged in coated paperboard cartons of 200mL Tetra Brik containers. Tetra Brik containers were stored for 6months at room temperature and analyzed at different days. Microbiological (total mesophilic aerobic bacteria, aerobic spores, Bacillus cereus, and enterobacteria counts), physical (dispersion stability and particle size distribution), chemical (hydroperoxide index and volatile profile evolution) and sensory analyses were performed on soymilks. Both UHPH and UHT soymilks did not present microbiological growth during storage. UHPH soymilk presented high colloidal stability and relevant decrease in hydroperoxide index during storage. On the other hand, almost all of the compounds associated to off-flavors were detected in the volatile profile of soymilk. Sensory results indicated that UHPH treatment did not produce changes in soymilk which could affect the panel perception for different UHT and UHPH soymilks and for selecting their preference.Soymilk constitutes one of the food industry sectors with the highest worldwide growth and its consumption has experienced a noticeable increase in the last years. The growing consumer demand for safe products, environmentally friendly processes and high quality nutritional foods has challenged the food industry to adapt the technological processes. This tendency impacts directly on traditional technologies, like heat treatments. In this sense, UHPH technology has been applied as an alternative to those thermal treatments. This research paper presents a comparative study between soymilk treated by UHPH and by UHT to produce a product stored at room temperature for 6months. Results showed stable levels of oxidation, high physical stability, no microbial growth and a positive trend of sensory response during the period analyzed for UHPH soymilk. Moreover, the UHPH system was designed to work at continuous flow, allowing its application in several industrial food processes.