Quality of commercial shelf-stable soymilk products.
Four brands of shelf-stable soymilks (three lots each) were evaluated for their quality. All samples were tested for trypsin inhibitor activity, microbial load (coliforms, aerobic mesophiles, and psychrotrophs), solids content, pH, color, and viscosity. Storage stability at 5 degrees C of the opened original containers was evaluated by microbiological analyses. Physical properties were consistent among three lots of the same brand, but varied among brands. Trypsin inhibitor activity ranged from 3.43 to 10.35 mg/g dried soymilk. The pH values of the soymilks varied between 6.41 and 7.34. Viscosity was measured between 16.5 and 26.4 mPa. Solids content varied considerably among soymilks, from 6.88 to 12.37% (wt/vol). Freshly opened commercial soymilk contained fewer than one microorganism per ml in all microbial counts. During storage at 5 degrees C, microbial counts increased sharply after 2 to 3 weeks. A single microorganism predominated in each stored sample. Shelf life (defined as the time during which aerobic mesophile counts remained below 10(6) CFU/ml) varied from 3 to 4 weeks. The appearance and pH of soymilks remained unchanged even after 4 weeks of storage. Five types of microorganisms were found in stored soymilk samples; none of them produced acid.
Department of Food Science and Human Nutrition, Iowa State University, Ames 50011, USA.
Y
Y
Bai
L A
LA
Wilson
B A
BA
Glatz
D001419:Bacteria / Q000254:growth & development / Q000302:isolation & purification; D015169:Colony Count, Microbial; D005511:Food Handling; D018857:Food Packaging; D006863:Hydrogen-Ion Concentration; D010940:Plant Proteins / Q000032:analysis; D013025:Glycine max / Q000737:chemistry / Q000382:microbiology*; D013997:Time Factors; D014361:Trypsin Inhibitors; D000516:alpha-Amylases / Q000037:antagonists & inhibitors
D010940:Plant Proteins; D014361:Trypsin Inhibitors; D000516:alpha-Amylases