Effects of blanching, freezing and canning on the carbohydrates in sweet corn

Authors: Whent, Monica; HOLLY, CHILDS - University Of Maryland; CHEANG, SHAWN - Uc Davis Medical Center; JIANG, JIANI - Uc Davis Medical Center; LEBRILLA, CARLITO - Uc Davis Medical Center; Luthria, Devanand - Dave; Bukowski, Michael; YU, LIANGLI - University Of Maryland; Pehrsson, Pamela; Wu, Xianli

Submitted to: Nutrients
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/20/2023
Publication Date: 10/24/2023
Citation: Whent, M.M., Holly, C., Cheang, S., Jiang, J., Lebrilla, C., Luthria, D.L., Bukowski, M.R., Yu, L., Pehrsson, P.R., Wu, X. 2023. Effects of blanching, freezing and canning on the carbohydrates in sweet corn. Nutrients. 12:21. https://doi.org/10.3390/foods12213885.
DOI: https://doi.org/10.3390/foods12213885

Interpretive Summary: Sweet corn is one of the most popular vegetables in the US and contains carbohydrates as major macronutrients. In this study, the effects of blanching, freezing and canning on carbohydrates in sweet corn were investigated. The fresh bi-color sweet corn was harvested from the field, and was processed immediately into frozen and canned samples. Simple sugars, starch and dietary fiber were measured according to the AOAC methods. The monosaccharide composition of total polysaccharides (MCTP) and glycosidic linkage of total polysaccharides (GLTP) were analyzed using UHPLC-MS. Sucrose is the major simple sugar, and IDF is the main contributor of TDF. Sucrose and total simple sugar were not altered after blanching or freezing, but were significantly reduced in the canned samples. Kestose is the only oligosaccharide identified in sweet corn, and it tended to decrease in all processed samples. Starch reduced in the two frozen samples but increased in the two canned samples. Two fractions of SDF did not differ between all samples, but TDF and IDF remained unchanged in blanched and frozen samples but increased in canned samples. MCTP and GLTP analyses found that polysaccharides were profoundly altered by different food processing methods.

Technical Abstract: Sweet corn is one of the most popular vegetables in the US and contains carbohydrates as major macronutrients. In this study, the effects of blanching, freezing, and canning on carbohydrates in sweet corn were investigated. The fresh bi-color sweet corn was harvested from the field and processed immediately into frozen or canned samples. Simple sugars, starch, and dietary fiber (DF) (including total DF (TDF), insoluble DF (IDF) and two fractions of soluble DF (SDF)) were measured according to the AOAC methods. Additional glycomic analysis including oligosaccharides, monosaccharide composition of total polysaccharides (MCTP) and glycosidic linkage of total polysaccharides (GLTP) were analyzed using UHPLC-MS. Sucrose is the major simple sugar, and IDF is the main contributor of TDF. Sucrose and total simple sugar concentrations were not altered after blanching or freezing, but were significantly reduced in canned samples. Kestose was the only oligosaccharide identified in sweet corn and decreased in all processed samples. Starch content decreased in frozen samples but increased in canned samples. While two SDF fractions did not differ across all samples, blanching, freezing and canning resulted in increases of TDF and IDF. Six monosaccharides were identified as major building blocks of the total polysaccharides from MCTP analysis, with the glucose representing >85% of total monosaccharides. Both glucose and total monosaccharide concentrations increased in two canned samples. GLTP were also profoundly altered by different food processing methods. Principal component analysis revealed different patterns of individual linkages for different processing groups. In conclusion, this study provided insights on the qualitative and quantitative changes of carbohydrates in sweet corn after food processing. The data are important for accurate assessment of the carbohydrate intake from different sweet corn products, and to further establishing diet and health relationships.