Annealing process improves the physical, functional, thermal, and rheological properties of Andean oca (Oxalis tuberosa) starch

Abstract

The characteristics of a native starch limit its application in the food industry; for this reason, it is important to investigate alternatives for obtaining modified starches with better characteristics and more possibilities of application. Oca (Oxalis tuberosa) starch was subjected to annealing process with a temperature of 42 and 50 C and starch:water ratios of 1:6 and 1:2 during 24 hr. The effects of the annealing process on thermal, structural, and rheological properties were investigated. The annealing at 50 C and 1:6 (starch:water) ratio yielded a starch with high peak viscosity, stability ratio, gelatinization temperature, and gel firmness, but low solubility and low swelling power. All annealed starch gels had a more elastic behavior (G 0 > G 00 ), lower viscosity and greater stability to retrogradation compared to native starch. The annealing process caused the rearrangement of amylopectin and amylose in the starch granule, obtaining a more orderly structure, which increased the thermal stability and functional properties of oca starch. Practical applicationsFew studies have been reported on chemical, physical, or enzymatic modification of native starches using the annealing process, none on oca starch. The annealing process improves the thermal stability and functional properties of oca starch, which can expand its application in the food industry. The starch produced in this work can be used as raw material for noodles, gluten-free bakery products, and as a thickening agent. | INTRODUCTIONOca (Oxalis tuberosa) is an important crop of the South American Andes (Cruz-Tirado et al., 2017), which has cylindrical or turbinate shape with a diameter of $20-40 mm and a length of $50-80 mm . The oca skin is often smooth with deep eyes and colors that can range from red, purple, pink, orange, and yellow (Sangketkit, Savage, Martin, Searle, & Mason, 2000). The main component of the oca tuber is starch ($60% dry weight), but it is also a source of protein (e.g., 1.1%, fresh weight basis), dietary fiber (e.g., 1.1%, fresh weight basis), and fructooligosaccharides (Jimenez, Rossi, & Samm an, 2015;Zhu & Cui, 2020). Also, orange and yellowvariety oca is rich in carotenoids, whereas pink and purple-variety oca is rich in anthocianyns (Zhu & Cui, 2020). For this reason, in some parts of South America, like Peru, oca is a staple food, being used in variety of dishes such as sopas or eaten cooked (Malice, Bizoux, Blas, & Baudoin, 2010). However, oca starch could be considered as a novel and non-conventional starch source for food and non-food

The Effect of Annealing Modification on Increasing Glucomannan Content of Porang (Amorphophallus Muelleri Blume) Flour

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Influence of Annealing Process Combined with Enzymatic Modification with Transglucosidase on Black Rice Starch

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Reducing oil absorption in pea starch through two-step annealing with varying temperatures

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