Characterization of a Spray-Dried Soymilk Powder and Changes Observed During Storage

Abstract

Physical characterization of a soymilk powder was carried out by electron microscopy. Chemical characterization was analyzed by proximate analysis, mineral composition by atomic absorption spectrometry, fatty acid composition by gas chromatography and protein composition by electrophoresis. The powder consists of large granules of 60-80 μm, which may be hollow, with smaller granules of 10-20 μm attached to them. Powder particles are covered by a layer of fat. During storage at 25 °C fat is spreading over the surface, while at -12 °C the fat is contracting. This change affected chemical stability, resulting in high level of fat oxidation when stored at 4 °C or 25 °C as well as a decrease in unsaturated fatty acids. Storage also affected the chemical properties of the re-constituted soymilk; the pH of a 12% soy powder suspension increased from 6.68 ± 0.05 to 7.06 ±0.08 after 12 months of storage. Storage temperature did not affect the pH of the suspension and this change could also not be ascribed to protein aggregation.

Spray drying and storage of probiotic‐enriched almond milk: probiotic survival and physicochemical properties

“…Ash, fat, and protein content were statistically higher in raw almond than in milk or powder, which is consistent with the addition of maltodextrin. All three components (ash, fat, and protein) were recuperated in the powder; a similar tendency was also observed for spray‐dried soymilk powder . Carbohydrates were significantly higher in almond milk powder (366 g kg −1 mean value) than in the raw material (202 g kg −1 ), due to the maltodextrin added to protect the bacteria and to enhance the spray‐drying process.…”

“…Approximately 2 g of powder was dried in a hot‐air oven at 103 ± 2 °C and the weight was controlled daily until a constant weight was reached …”

“…During the operation, the product is exposed to high temperatures from hot air, but for a very short time; this dehydration process is supposed to produce high quality foods . Both milk and vegetable beverages are dried using an atomizer to produce instant milk or vegetable‐based beverages obtained from soy or coconut ingredients …”

Shelf‐life study of spray‐dried groundnut milk powder

“…However, storage resulted in an increase in the free fatty acid content in all samples of groundnut milk powder (Table 1, Figure 5) which may be due to the breaking of long chain fatty acid into individual fatty acid entities (Siwach et al, 2016). Similarly, Osthoff, Hugo, Wyk, Wit, and Meyer (2010) reported deterioration in lipid quality of soymilk powder when stored at temperature greater than 25 C. The percent free fatty acid values in groundnut milk powder were 0.481% as oleic acid in fresh samples, upon storage these values recorded an increase (0.550-2.021% and 0.531-1.870% in aluminum foil package and metal tin can, respectively). It was observed that the free fatty acid (FFA) increase was relatively higher in aluminum foil package than metal tin can.…”

Impact of high intensity pulsed electric fields or heat treatments on the fatty acid and mineral profiles of a fruit juice–soymilk beverage during storage

“…Regarding soy foods, Bhardwaj, Hamama, Rangappa, Joshi, and Sapra (2007) stated that their mineral content is affected by soybean genotype and growing location. However, soymilk powder, soy-yogurt and tofu are characterized by a high Ca and Mg content and low concentration of Fe, Zn, Cu and Mn (Adentunji, Betiku, & Solomon, 2006;Bhardwaj et al, 2007;Osthoff, Hugo, Van Wyk, De Wit, & Meyer, 2010).…”