Ultrafiltration studies of foods: Part 1—The removal of undesirable components in soymilk and the effects on the quality of the spray-dried powder

Production of instant soymilk powders by ultrafiltration, spray drying and fluidized bed agglomeration

“…It can be seen that the powders obtained from the ultrafiltered concentrates exhibited a significant (p 6 0.05) increase in protein and fat contents, but decrease in carbohydrate and ash contents as compared with that obtained from the non-ultrafiltered soymilk. This was due to the removal of low molecular weight oligosaccharides and inorganic salts by ultrafiltration as described by Ang et al (1986) and Omosaiye et al (1978). Most of the soy proteins have molecular weights ranging from 200,000 to 600,000 (Ang et al, 1986;Pomeranz, 1991).…”

“…This concentration is comparable to that obtained by ultrafiltration (see Section 3.3). However, ultrafiltration was preferable not only for concentration, but also removal of anti-nutritional low molecular weight components of soymilk (Ang et al, 1986;Omosaiye et al, 1978) which cannot be achieved by evaporation.…”

“…Its use is an attractive alternative to conventional evaporation processes as it is a non-thermal treatment, as well as one with mild operating conditions. The applications of ultrafiltration in soymilk processing are not only concentration, but also removal of anti-nutritional low molecular weight components such as oligosaccharides and phytic acid (Ang, Kwik, Lee, & Theng, 1986;Omosaiye, Cheryan, & Matthews, 1978). The low molecular weight oligosaccharides, raffinose and stachyose have been implicated as causative factors in digestive disturbances, such as flatulence while phytic acid has been considered to lower the mineral biodegradability by forming insoluble complexes with di-and tri-valent ions at neutral pH (Ang et al, 1986;Omosaiye et al, 1978;Pomeranz, 1991).…”

“…A spray-drying system for soymilk has been characterized at various combinations of inlet air temperature, feed rate, and atomizer speed on outlet air and product temperatures, thermal and evaporative efficiencies (Perez-Munoz & Flores, 1997a), and particle size of spray-dried soymilk powders (Perez-Munoz & Flores, 1997b). Spray-drying studies were also carried out on the ultrafiltered soymilk concentrates (Ang et al, 1986). The results revealed that the nitrogen solubility index (NSI) of the spray-dried powder improved with percent water removal during ultrafiltration and also by the addition of sucrose to the concentrate prior to spray drying.…”

Genetic and Environmental Variation for Seed Yield, Protein, Lipid and Amino Acid Composition in Cowpea (Vigna unguiculata (L) Walp)

“…Seeds were hydrolysed by heating overnight at 110¡C in 6 M HCl under nitrogen in sealed ampoules (Ang et al 1986). Tryptophan was measured as described by Miller (1967) and modiÐed by Mba et al (1974), because it was destroyed under acid hydrolysis.…”