CHANGES IN SOYMILK QUALITY AS A FUNCTION OF COMPOSITION AND STORAGE

ABSTRACT

Three soymilk products formulated with different concentrations of fat, sugar and starch were evaluated for changes in their physical properties and volatiles profile over time (3 months) under different temperatures (4, 22 and 38C) of storage. Samples were tested for pH, color, viscosity and volatile flavor changes. The pH and color of the soymilks decreased significantly during the first month of storage and then remained stable over time. Color and viscosity of the soymilk products were affected by both the soymilk composition and storage treatment. The high‐fat soymilk sample (product C) had the whitest color (lower ΔE) and the lowest viscosity. Storage at 38C negatively affected the color. The viscosities of the soymilk products stored at 4C were the lowest among the treatments. The major volatiles identified in all soymilk products were hexanal, heptanal, octanal, nonanal, hexanol, 1‐octen‐3‐ol, benzaldehyde, 2‐pentyl furan and 2‐ethyl furan. The intensities of the volatile compounds in the soymilk products increased during the first weeks of storage, particularly when stored at 38C. The intensities, however, decreased gradually over time. Among the three formulated soymilk products, the sweetened sample (product B) gave the lowest flavor intensities under all three temperatures of storage. Overall, storage at 4C and addition of sugar preserve best the soymilk quality.

PRACTICAL APPLICATIONS

Soy products are well appreciated for their nutritional and potential health benefits. Soy beverage consumption is increasing among North American consumers because of improvements in soy beverage quality and processing technologies. There is, however, a demand for new value‐added soy‐based drinks with improved “functional” (health‐benefiting) properties. Soy beverage could be an excellent carrier for “functional” or “nutritive” ingredients such as minerals, vitamins and omega 3 oils; however, addition of such ingredients may affect the stability of the product and requires the development appropriate of technologies for their incorporation. Results from this project provide new knowledge on the storage stability and quality of three different soy product formulations. The information could be useful in the establishment of optimal conditions for processing of functional soy beverages, for use by the food industry.