Abstract |
Four pilot-plant units were operated with asparagus, peas, corn, beans, beets, pumpkin and spinach to establish the potential for new blanching systems with low wastewater generation. The systems investigated were microwave, hot-gas, steam, and hot-water. Single runs of about one hour duration were made for each commodity with each blanching system. Wastewater volume was measured and samples were analyzed for COD, SS, and pH. The most striking result obtained was the small volume of steam condensate formed during hot-gas blanching. Canned samples of vegetable material from each blancher were prepared for quality evaluation after storage. Taste panels showed no significant flavor preference for samples from any individual blanching system. The system used had no significant effect on the vitamin and mineral retention of blanched or canned samples. The oxygen content of canned samples was lowest for hot-gas blanching compared to the other three systems. Estimates of the cost of blanching using commercial-scale units gave (dollars/ton blanched): microwave, 18.47; hot-gas, 3.39; steam, 2.21; and hot-water, 2.36. (Author) |