Characterisation and functional properties of watermelon (Citrullus lanatus) seed proteins

• Published in: Journal of the science of food and agriculture Vol. 91; no. 1; pp. 113 - 121
• Main Authors: Wani, Ali Abas, Sogi, Dalbir Singh, Singh, Preeti, Wani, Idrees Ahmed, Shivhare, Uma S
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 15.01.2011; Wiley; John Wiley and Sons, Limited
• Subjects: Albumins - chemistry; amino acid analysis; Biological and medical sciences; Citrullus - chemistry; Citrullus lanatus; digestibility; food analysis; food composition; Food industries; Food science; Fruit and vegetable industries; Fruits; functional properties; Fundamental and applied biological sciences. Psychology; Globulins - chemistry; Glutens - chemistry; meals (products); novel foods; nutrient content; Nutrition; Nutritive Value; Plant Proteins - chemistry; Polypeptides; protein digestibility; Proteins; seed proteins; Seeds; Seeds - chemistry; thermal properties; watermelon seed protein; watermelons; Seeds; Fruit; Watermelon; Citrullus lanatus; Cucurbitaceae; amino acid analysis; watermelon seed protein; Protein; Thermal properties; protein digestibility; Dicotyledones; Analysis; Angiospermae; Spermatophyta; Digestibility
• ISSN: 0022-5142; 1097-0010
• DOI: 10.1002/jsfa.4160

BACKGROUND: People in developing countries depend largely on non‐conventional protein sources to augment the availability of proteins in their diets. Watermelon seed meal is reported to contain an adequate amount of nutritional proteins that could be extracted for use as nutritional ingredients in food products. RESULTS: Osborne classification showed that globulin was the major protein (≥500 g kg ⁻¹) present in watermelon seed meal, followed by albumin and glutelin. Sodium dodecyl sulfate polyacrylamide gel electrophoresis indicated that the polypeptides had low molecular weights ranging from 35 to 47 kDa. Isoelectric focusing revealed that the isoelectric point of most proteins was in the acidic range 4-6. These proteins are rich in aspartic acid, glutamic acid and serine. An increase in pH (5-9) significantly (P < 0.05) decreased the denaturation enthalpy of these proteins. Among functional properties, albumin exhibited a much higher dispersibility index (810.3-869.6 g kg⁻¹) than globulin (227.8-245.4 g kg⁻¹), glutelin (182.1-187.7 g kg⁻¹) and prolamin (162.3-177.7 g kg⁻¹). Digestibility was in the ranges 760.6-910.0 and 765.5-888.5 g kg⁻¹ for Mateera and Sugar Baby watermelon protein fractions respectively, while surface hydrophobicity ranged from 126.4 to 173.2 and from 125.8 to 169.3 respectively. The foaming and emulsifying properties of albumin were better than those of the other proteins studied. CONCLUSION: The good nutritional and functional properties of watermelon seed meal proteins suggest their potential use in food formulations. Copyright