Effects of Different Precooling Methods on Storage Quality of Sweet Corn

In order to explore the effects of different precooling methods on the storage quality of sweet corn, we used three precooling methods (cold storage precooling, differential pressure precooling and slurry ice precooling) to treat sweet corn. Subsequently, sweet corn was stored at 0 ℃ and evaluated for internal temperature, sensory quality, color difference, respiration rate, ethylene production rate, and the contents of total soluble solids (TSS), soluble starch, total soluble sugar, glucose, fructose and sucrose. The results showed that slurry ice precooling provided the best quality preservation during storage, followed by differential pressure precooling. Slurry ice precooling could quickly reduce the internal temperature, delay bract yellowing, keep the grain color, maintain the sensory quality, inhibit the respiration and ethylene release rates of sweet corn. In addition, slurry ice precooling could maintain the contents of TSS, soluble starch, soluble sugar, glucose, fructose and sucrose in corn grains. At day 28 of storage, the TSS content of the slurry ice precooled sample was 13.8%, significantly higher than that observed with differential pressure precooling (13.4%) and cold storage precooling (13.1%) (P < 0.05). The difference between the latter two was, however, not significant (P > 0.05). Meanwhile, the sucrose content of the slurry ice precooling group was as high as 120.4 mg/g, the sucrose content of the differential pressure precooling group was 118.0 mg/g, and the sucrose content of the cold storage precooling group was only 92.3 mg/g. The sucrose content of the slurry ice precooling group was the highest, followed by that of the differential pressure precooling group. The sucrose content of the cold storage precooling group was low at the end of storage. In summary, the quality deterioration of sweet corn can be significantly delayed by slurry ice precooling. This study provides a theoretical basis for the selection of a suitable precooling method for sweet corn.