(P06-050-23) Effects of Freezing and Canning on Carbohydrates in Sweet Corn

Objectives: Sweet corn is one of the most consumed vegetables in the US and rich in carbohydrates. Freezing and canning are the two primary industrial processing methods for sweet corn. In this study, the effects of freezing, canning and storage on carbohydrates in sweet corn were investigated.

Methods: The fresh bi-color sweet corn was harvested from the field, which was immediately processed into the frozen and canned samples based on the methods that simulated industrial processing. Simple sugars, starch and dietary fiber contents including total dietary fiber (TDF), insoluble dietary fiber (IDF) and two fractions of soluble dietary fiber (SDFP, soluble in water but not in ethanol; and SDFS, soluble in water and ethanol) in unprocessed sample (“Baseline”) and four samples taken at different processing stages (“Blanch”, after blanch; “Can 0”, after canning; “Can 1”, one month after canning; “FO 1”, one month after freezing with kernels off the cob; and “FC 1”, one month after freezing with kernels on the cob) were measured by relevant AOAC methods.

Results: Fresh sweet corn contained 10.3 g/100 g fresh weight (FW) total simple sugar (TSG), 6.9 g/100 g FW starch and 2.1 g/100 g FW TDF. Sucrose and IDF are major contributors to TSG and TDF. Sucrose and TSG were not altered in “Blanch”, “FO 1 and “FC 1” samples, but were significantly reduced in “Can 0” and “Can 1” samples. While starch levels slightly reduced in the two frozen samples but increased in the two canned samples. SDFP and SDFS did not differ between all samples. TDF and IDF in “Baseline” were 8.4 and 5.8 g/100 g dry weight (DW), whereas these two fractions increased to 10.5 and 7.9 g/100g DW in “Blanch”, 12.8 and 10.3 g/100 g DW in “FO 1”, 12.4 and 10.0 g/100 g DW in “FC 1”, 13.7 and 11.5 g/100 g DW in “Can 0”, and 13.9 and 11.4 g/100 g DW in “Can 1”.

Conclusions: Canning may convert sugar into starch in sweet corn. TDF increased in all processed samples due to the increase of IDF. IDF increased likely because of the formation of resistant starch. Food processing, especially canning, changed the carbohydrate profiles and potentially impact the physiological functions of sweet corn.

Funding Sources: USDA