The effect of drying temperature and sodium caseinate concentration on the functional and physical properties of spray-d
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ORIGINAL ARTICLE
The effect of drying temperature and sodium caseinate concentration on the functional and physical properties of spraydried coconut milk Zalizawati Abdullah1,2 • Farah Saleena Taip1 • Siti Mazlina Mustapa Kamal1 Ribhan Zafira Abdul Rahman3
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Revised: 4 August 2020 / Accepted: 24 September 2020 Ó Association of Food Scientists & Technologists (India) 2020
Abstract This study investigated the effect of drying temperature on the stability and quality of spray-dried coconut milk. A low concentration (1–2% w/w) of sodium caseinate (SC) was used as emulsifying agent with 8–9% of maltodextrin. The spray drying temperature was varied from 140 to 180 °C. Emulsions prepared at different SC concentration remained stable without phase separation for 24 h. Higher the SC concentration produced smaller-sized of droplet and powder particles. The spray dried coconut milk has a skin-forming structure. Emulsion with low concentration of SC (1% w/w) is unstable during atomisation process due to re-coalescence of fat. Adding SC to the emulsion reduce the moisture content to less than 5%. However, drying the emulsions at 180 °C gave negative impact to the powder properties. Some particles rupture and lead to high free fat content, high insolubility and larger fat droplet size. Presence of fleck is also noticed in the powder. Keywords Coconut milk powder Spray drying Emulsion stability Powder solubility Microstructure Particle size
& Farah Saleena Taip [email protected] 1
Department of Process and Food Engineering, Faculty of Engineering, Universiti Putra Malaysia, 43400 Serdang, Malaysia
2
Faculty of Chemical Engineering, Universiti Teknologi MARA, 40450 Shah Alam, Malaysia
3
Department of Electrical and Electronic Engineering, Faculty of Engineering, Universiti Putra Malaysia, 43400 Serdang, Malaysia
Introduction Spray dried coconut milk powder is plant-based milk and widely used in Asian foods and beverages. Spray drying is a process where liquid is atomised to form small droplets and then fed into a hot medium. The numerous small droplets have a large surface area that allows the fast removal of moisture. However, several studies have found that although near-instantaneous evaporation (milliseconds) could be achieved, some delicate components are still affected by the thermal contact (Fang et al. 2012; Haque and Adhikari 2015). Water and fat are the major components in coconut milk, making it a natural oil-in-water emulsion. This emulsion is obtained by the extraction of grated coconut meat. Fresh coconut milk contains almost 40% fat and 4% protein (Seow and Gwee 1997). Because coconut milk is a high-fat emulsion, additives are required to minimise the oxidation of fat and to allow the powder to flow freely when spray drying the coconut milk. Additives are required to achieve a stable emulsion which leads to production of a stable powder. Santana et al. (2017) found out that more than 20% of maltodextrin is required to allow the free flow of babassu coconut milk from the atomiser. Therefore
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