GRANULOMETRY AND ENERGY CONSUMPTION AS INDICATORS OF DISINTEGRATION EFFICIENCY IN A HAMMER MILL ADAPTED TO EXTRACTING ARROWROOT STARCH (Maranta arundinacea) IN COMPARISON TO STARCH EXTRACTION FROM CASSAVA

ABSTRACT The commercial sector of starch extraction has fully automated plants with a minimum scale of 200 ton.day–1, which extracts starch from maize and cassava in Brazil. Although these starches are commodities, the market demands starches with special properties obtained without chemical modifications. A higher-priced starch can compensate for small-scale extraction, as in the case of arrowroot starch, which would correspond to an alternative income for the producer. As a small-scale equipment was not available in Brazil, it was necessary to adapt a hammer mill for arrowroot starch extraction, which should have a performance similar to that obtained from cassava roots using industrial grinders. The degree of disintegration and energy consumption were adopted as the efficiency indexes. The hammer mill was equipped with two perforated plates. The results showed that use of an adapted hammer mill provides an average diameter of 74.64 ± 0.09 μm for perforated plate 1 (TP1) and 76.62 ± 0.06 μm for TP2; these results were equivalent to those obtained with cassava in the respective perforations which, in turn, was comparable to the degree of grinding obtained with large industrial equipment. The specific energy consumption needs for arrowroot disintegration varied from 31.47 to 48.91 kJ.kg–1, which was considered close to that calculated for large-scale industrial cassava roots grinders, reported at 37.03 kJ.kg–1.摘要 巴西商业级淀粉提取行业已实现工厂全自动化，单厂最小产能达200吨·日⁻¹，以玉米和木薯为原料提取淀粉。尽管此类淀粉属于大宗商品，但市场对无需化学改性即可获得的特殊性能淀粉存在需求。例如竹芋淀粉这类高价产品，可弥补小规模提取的成本缺口，为生产商提供替代性收入来源。由于巴西此前暂无适配的小型提取设备，研究团队对锤式粉碎机（hammer mill）进行改装以用于竹芋淀粉（arrowroot starch）提取，要求其性能达到工业粉碎机处理木薯原料的水平。本研究以物料解离度与能耗作为效率评价指标。该改装锤式粉碎机配备两块冲孔筛板（perforated plate）。测试结果显示，使用冲孔筛板1（TP1）时，物料平均粒径为74.64±0.09 μm；使用冲孔筛板2（TP2）时则为76.62±0.06 μm。上述结果与工业粉碎机处理木薯原料的对应筛板下的粒径结果相当，亦符合大型工业设备的粉碎度水平。竹芋原料粉碎所需的单位能耗（specific energy consumption）介于31.47~48.91 kJ·kg⁻¹之间，与已有研究报道的大型工业木薯粉碎机单位能耗（37.03 kJ·kg⁻¹）相近。