Synthesis, Characterization, and Investigation of Coating Properties of Carboxymethyl Acorn Starch (CMAS)

Kyrgyzstan is a landlocked country in Central Asia, famous for its crystal-clear lakes, majestic Tien Shan Mountains that bisect the territory of Turkistan, and magnificent natural beauty. This study aims to evaluate the fruit (acorns) of the oak trees (Quercus robur L.) grown in Bishkek, the capital city of Kyrgyzstan. For this purpose, carboxymethyl acorn starch (CMAS), which is not synthesized in literature, is first synthesized by isolating acorn starch (AS) from the acorns. The structures of CMASs are characterized by H-1(C-13)-NMR, FT-IR, XRD, and SEM techniques. The viscosities of the samples with different degrees of substitution (DS), such as 0.62, 0.95, and 1.01, determined by the titrimetric method, are measured as 247, 600, and 388 mPa s, respectively. In addition, considering the film-forming properties of CMASs, tomatoes are coated, and their shelf lives are investigated. Weight loss (WL) is 38.36 in control and 25.52 in coated tomato after 4 weeks. The needle penetration depth is measured as 388 mm in the control and 249 mm in the coated tomato. Total soluble solids (TSS) content showed approximate results in both samples. Control tomatoes containing 78.8 mg 100 g(-1) ascorbic acid lost significantly during storage, reducing to 13.90 mg 100 g(-1).

Keyword: acorn starch; carboxymethylation; NMR; storage quality