title: Emulsion stabilizing capacity of intact starch granules modified by heat treatment or octenyl succinic anhydride.
abstract: Starch granules are an interesting stabilizer candidate for food-grade Pickering emulsions. The stabilizing capacity of seven different intact starch granules for making oil-in-water emulsions has been the topic of this screening study. The starches were from quinoa; rice; maize; waxy varieties of rice, maize, and barley; and high-amylose maize. The starches were studied in their native state, heat treated, and modified by octenyl succinic anhydride (OSA). The effect of varying the continuous phase, both with and without salt in a phosphate buffer, was also studied. Quinoa, which had the smallest granule size, had the best capacity to stabilize oil drops, especially when the granules had been hydrophobically modified by heat treatment or by OSA. The average drop diameter (d 32) in these emulsions varied from 270 to 50 μm, where decreasing drop size and less aggregation was promoted by high starch concentration and absence of salt in the system. Of all the starch varieties studied, quinoa had the best overall emulsifying capacity, and OSA modified quinoa starch in particular. Although the size of the drops was relatively large, the drops themselves were in many instances extremely stable. In the cases where the system could stabilize droplets, even when they were so large that they were visible to the naked eye, they remained stable and the measured droplet sizes after 2 years of storage were essentially unchanged from the initial droplet size. This somewhat surprising result has been attributed to the thickness of the adsorbed starch layer providing steric stabilization. The starch particle-stabilized Pickering emulsion systems studied in this work has potential practical application such as being suitable for encapsulation of ingredients in food and pharmaceutical products.
authors.affiliation: Department of Food Technology Engineering and Nutrition, Lund University SE 221 00, Lund, Sweden.
authors.forename: Anna
authors.initials: A
authors.lastname: Timgren
authors.affiliation: Department of Food Technology Engineering and Nutrition, Lund University SE 221 00, Lund, Sweden.
authors.forename: Marilyn
authors.initials: M
authors.lastname: Rayner
authors.affiliation: Department of Food Technology Engineering and Nutrition, Lund University SE 221 00, Lund, Sweden.
authors.forename: Petr
authors.initials: P
authors.lastname: Dejmek
authors.affiliation: Department of Food Technology Engineering and Nutrition, Lund University SE 221 00, Lund, Sweden ; Speximo AB, Ideon Science Park, Scheelevägen 15 SE 223 70, Lund, Sweden.
authors.forename: Diana
authors.initials: D
authors.lastname: Marku
authors.affiliation: Department of Food Technology Engineering and Nutrition, Lund University SE 221 00, Lund, Sweden ; Speximo AB, Ideon Science Park, Scheelevägen 15 SE 223 70, Lund, Sweden.
authors.forename: Malin
authors.initials: M
authors.lastname: Sjöö
keywords: Granule size; OSA modification; Pickering emulsion; heat treatment; quinoa starch; starch granules