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 .

Changes in the Crystallinity Degree of Starch Having Different Types of Crystal Structure after Mechanical Pretreatment

“…Grinding and mechanochemical processes are very energy-intensive, therefore, even minor optimization of these processes may have substantial economic effects [27][28][29][30]. Today, energy efficiency for mechanical disordering of starch is one of relevant questions [31].…”

COMPARISON OF ARROWROOT (Maranta arundinacea) AND CASSAVA STARCH EXTRACTION IN SEPARATION, CONCENTRATION, AND PURIFICATION USING A ROTATING SIEVE UNDER WATER

“…The rotary sieve shown in Figure 1 was mounted in the line with the hammer mill (a) (Branco et al, 2019) just after the disintegration process (b). The sieve consists of a hexagonal frame (c) covered by an 80 mesh (180 µm) nylon mesh that rotates counterclockwise around the axis.…”

“…The raw material was disintegrated in the hammer mill and the mass was loaded at a rate of 0.047 kg.s -1 (2.86 kg.min -1 ) (Branco et al, 2019) at the inlet of the rotating screen. In continuous feeding, the chute collected the water and starch suspension, while the mass extracted by the water jet was loaded as fibrous bagasse residue, as shown in Figure 2A, the outlet chute (a) and Figure 2B.…”

“…Additionally, cassava roots with 65.2% moisture of cultivar intended for industrial application were used for comparison. Both raw materials were disintegrated in the hammer mill and sieved to determine the Sauter diameter as per the method used by Branco et al (2019). Table 1 shows the average Sauter diameter of the disintegrated masses of the raw materials used in the sieve.…”

“…Grinding was evaluated as the first operation for starch extraction in a small equipment by Branco et al (2019) as an alternative to replace the traditional graters of metal saws in a hammer mill. They demonstrated that it was possible to obtain a mass with particle size close to that obtained using industrial equipment while saving energy and having a low maintenance cost.…”