Development of improved solar fish drying process and quality evaluation of dried anchovies (Engraulis encrasicolus)

Abstract

Open sun drying (OSD) has been a fish processing method for ages. In Ghana women form a large number of processors. Post-harvest losses still prevail in the trade due to poor fish handling, processing and storage which results in poor quality of dried fish. Solar drying has been introduced to improve on quality of OSD dried fish. A survey of open sun drying practices (OSD) at Kasoa (Central Region) and Tema (Greater Accra Region) showed poor hygiene practices and low value of products. The current study assessed prevailing OSD fish drying methods in Accra and Central region and tested the effect of a new method using a solar dryer on the final quality of anchovies. Fresh anchovies were dried by a new drying method using for a Hohenheim solar tunnel dryer (STD) in Greater Accra, and the quality of dried anchovies using STD was compared with OSD dried anchovies at two different locations at Kasoa (DAK-A and DAK-B). The study showed a shorter drying time for the STD method (7-8 hours; 9:0am and 3:30pm) on a sunny rainless and cloudless day, compared with OSD (1-3 days). The moisture values were 14.16 ± 0.03%, 13.22 ± 0.06% and 11.84 ± 0.08 % for DAK-A, DAK-B and STD. Samples DAK-A, DAK-B and STD had protein values of 62.17 ± 0.16%, 70.01 ± 0.28 % and 74.83 ± 0.45% respectively. Fat content was 4.25 ± 0.15%, 4.12 ± 0.01% and 4.00± 0.10% for DAK-A, DAK-B and STD respectively. Total ash values for DAK-A, DAK-B and STD were 11.11 ± .08%, 12.02 ± 0.06% and 9.57 ± 0.04 %. The FFA values for DAK-A, DAK-B and STD were 61.47%, 57.03% and 39.19% respectively, all above standard limit of (0.5% -1.5% oleic acid). Peroxide values were 55.47 meq 02/kg, 3.25meq 02/kg, and 4.29 meq 02/kg for DAK-A, DAK-B and STD respectively Histamine levels which were within acceptable limits were 22.2 ppm,( DAK-A,) 13.02 ppm(DAK-B) and 18.55 ppm (STD). The (aW) varied from DAK-A (0.64%,), to 0.51% (STD). STD was darker than DAK-A and DAK-B. In terms of sensory preference, Sample DAK-A was the most preferred followed by DAK-B and STD in terms of the overall acceptability of the samples. In conclusion, an improved processing method for a solar tunnel dryer can improve most of the quality indices, however due to higher temperatures of STD one cannot achieve similar quality as exists in the OSD method