Characteristics of soymilk pasteurized by ultra high pressure homogenization (UHPH)

• Pasteurization by Ultra High Pressure Homogenization (UHPH) was applied on soymilk.
• UHPH soymilks were compared to thermal-pasteurized soymilk during storage for 28 days at 4 °C.
• UHPH soymilks achieved high microbiological stability during storage.
• Thermal pasteurization reached lower physical and chemical stability than UHPH treatment.
• UHPH soymilk achieved better sensory acceptance than pasteurized sample.

The effect of ultra high pressure homogenization (UHPH) at 200 MPa combined with 55 and 75 °C of inlet temperature on soymilk was studied. UHPH-treated soymilks were compared with the base product (untreated sample) and pasteurized (90 °C, 30 s) soymilk. Microbiological (total mesophilic aerobic bacteria, aerobic spores and enterobacterial counts), colloidal and color stability, volatile profile evolution and sensory analysis were performed on soymilks. Samples were analyzed at 1, 7, 14 and 28 days while stored at 4 °C. UHPH-treated soymilk presented higher microbiological reduction and higher colloidal stability than pasteurized soymilk during the storage. In this sense, both UHPH treatments showed high color stability and most of the compounds identified were related to off-flavors of soymilk according to published studies. Sensory results indicated that soymilk treated at 200 MPa and 55 °C of inlet temperature achieved better sensory acceptance than pasteurized soymilk.Industrial relevanceThe consumption of soymilk in western countries have experimented a noticeable increase in the last decade. Consumer opinion is a key element for the development and modernization of the industrial process. In the case of soymilk, heat treatments may compromise the nutritional and sensorial qualities of the product. UHPH is a technology which uses the combined effect, high pressure and temperature to improve quality aspects of soymilk. This research paper presents a comparative study between soymilk treated by UHPH and by pasteurization to produce a product stored under refrigeration conditions during 28 days. During this period, UHPH soymilks presented a greater microbiological reduction, a higher colloidal and color stability than pasteurized soymilk. These results were confirmed by sensory analysis which, in addition, indicated better sensory acceptance for UHPH soymilk than pasteurized samples. Moreover, UHPH system was designed to work at continuous flow, allowing its application in several industrial food processes.