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Assessment of Post Harvest Loss of Wet Fish: a Novel Approach Based on Sensory Indicator Assessment

A. AKM. Nowsad
Department of Fisheries Technology Bangladesh Agricultural University Mymensingh-2202, Bangladesh

J.F. Polanco
Professor
University of Cantabria, Spain

S.M. Sayem
Assistant Professor
Department of Agricultural Statistics, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh

M.M. Hossain
Senior Upazila Fisheries Officer, Mithamoin Upazila, Kishoreganj, Department of Fisheries, Bangladesh

M.N. Hassan
Fish Inspection & Quality Control Officer, Fish Inspection & Quality Control Officer, Fish Inspection and Quality Control Wing- Khulna, Department of Fisheries, Bangladesh

Abstract/ Executive Summary:

As a very common feature of fish marketing, small-scale fisheries in tropical countries suffers from huge post-harvest loss every year. A method was proposed to quantify the post-harvest quality loss of wet fish using sensory based assessment tool. The assessments were conducted on four fish species (rohu Labeo rohita; Ilish Tenualosa ilisha, catfish Pangasius sutchi and tilapia Oreochromis niloticus) in different steps of major distribution channels in Bangladesh for a year. Sensory quality defect point data were standardized with corresponding biochemical and microbiological quality parameters through interval estimate based on regression analysis, where a “near to actual” sensory quality breaking point was found to be DP 3.3. High value of goodness of fit 2 R indicated a highly fitted regression model for all the fishes tested, with highly significant (p<0.01) estimated regression coefficients. Percent quality loss of fish at each step of distribution channel was determined using DP 3.3, constructing a (1-α) confidence interval for average percentage of defective fish. The loss assessment study indicated that fish did not lose quality during handling by the fishermen, and fish farmers or at landing centers and primary fish markets, except fresh T. ilisha destined for consumer market. While, T. ilisha used for salting during glut catch suffered substantial loss. Most of the quality losses were initiated at the transporters and commission agents, from 4% in P. sutchi to 11% in O. niloticus. When fish come to retailers, a 16% loss was recognized in L. rohita and O. niloticus, but 7% in P. sutchi and 9% in T. ilisha. Higher loss was observed in fish vendors, from 10% - 19%. Considering the retailers as the end-point stake in the fish distribution chain, study revealed the range of fish quality loss was 7-16% in four major consumed species in Bangladesh. The method was further validated in assessing the quality of 24 other major commercial fish species in different seasons and locations country-wide for two consecutive years and found identical results. The results suggest that the new method can be applied to any fish in quantifying the qualitative loss.

Keywords: Post-harvest fish loss, Distribution channel, Quality indicators, Qualitative loss, New loss assessment method

Location: Department of Fisheries Technology Bangladesh Agricultural University Mymensingh-2202, Bangladesh

Start Date:

End Date:

Program Area: Postharvest and Agro-processing

Commodity: Fish

Objectives:

To study is an attempt of assessing post-harvest quality loss of wet fish under a holistic approach incorporating all steps of major fish distribution channels where potential loss may occur.

Methodology:

In the present experiment, based on Howgate, the qualitative fish freshness assessment tool was revitalized to quantify the post-harvest fish loss, while the sensory defect points were standardized by several chemical and microbiological indicators. The assessments were conducted on three aquaculture species (rohu, Labeo rohita; pangas catfish, Pangasius sutchi; and tilapia, Oreochromis niloticus) and one captured species (river shad ilish, Tenualosa ilisha), in different steps of 11 major fish distribution channels (FDC) of the country for a year covering both summer and winter months. In every distribution step, at least five lots of same fish and 3 individual measurements for each lot were assessed. The quality defects of the same fish or same lot of fish were assessed during its movement from fish farmer/fisherman; to commission agent (CA)-1(commission agent in primary market); to transporter/wholesaler; to CA -2 (commission agent in secondary market); to retailer and vendor. Time required to move fish from harvest to retail sale in the distribution chain has been present. Field data collectors moved along with the fish from the harvest or landing centers through these distribution steps up to retailers and/ or vendors and assessed the quality of same fish or same lot of fish through the distribution chain. Average of all data for a single fish in each step of FDC was taken as average quality defect point, In sensory quality defect analysis of wet fish, sensory quality breaking point lies within the DP range of >3 to <4. The range is very wide. Therefore, a near to actual sensory quality breaking point needs to be understood to determine the percent quality loss. In order to correlate the sensory quality breaking points, several biochemical and microbiological quality parameters of fish were assessed and in the laboratory conditions, their quality breaking points were determined corresponding to each sensory DPs. When these biochemical and microbiological quality breaking points were plotted against the sensory quality DPs, a near to accurate sensory quality breaking point was pointed out. Fishes were purchased live, or in premium quality fresh condition as in case of T. ilisha, brought to the laboratory and allowed to stand at ambient temperature (28-32 ^oC) for deterioration. Samples from the spoiling fishes were collected at regular intervals in course of deterioration and several biochemical and microbiological parameters were measured corresponding to each sensory DPs. The non-protein nitrogen (NPN), total volatile base nitrogen (TVBN), protein solubility (PS), peroxide value (PV), thiobarbituric acid reactive substance value (TBA), pH and surface aerobic plate count (APC) were measured corresponding to the obtained sensory DPs. Standard methods were followed for the estimation of biochemical parameters. The PV and TBA were determined according to the modified method. For the determination of surface APC, bacteriological samples were collected in duplicate from 1.5 cm² area of skin at the base of pectoral fin above the lateral line of each of the fish. A 1.5 cm² area marked on sterile filter paper (Advantec 131, 55 mm, Toyo Roshi Kaisha Ltd. Japan) was cut-off and placed on the skin surface. A piece (1 cm x 1 cm) of sterile cotton (Cut Cotton, 4 cm x 4 cm, Tomonari Salinity Material Co. Ltd. Japan) was wet with 1.5% NaCl and the designated skin surface was wiped with a forceps. Wiped cotton was dissolved in 20 ml sterile 1.5% NaCl for 30 sec, squeezed well to drop out NaCl solution and used for second time wiping. Similar wiping of surface skin and subsequent dissolving in NaCl solution were done 5 times. The NaCl solution with collected bacterial cells was serially diluted and then pour plated in duplicate on appropriate media (poly peptone0.5%, yeast 0.3%, MgSO₄ 0.05%, K₂HPO₄ 0.2%, KH₂PO₄ 0.04%, agar-1.2%, NaCl 1.5% pH 7.4). The plates were incubated at 37 ºC and APC was done up to 24 h.

Source of Information: SAARC J. Agri., 13(1):75-89 (2015)

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

In existing sensory quality assessment of fish, t h e r a n g e o f quality breaking point is very wide (>3 to <4). Therefore, a near to actual sensory quality breaking point was determined through regression analysis between several chemico-microbiological quality parameters and the corresponding sensory defect characteristics of four spoiling fishes in laboratory conditions. The regression analysis found a near to actual sensory quality breaking point, DP 3.3. High value of goodness of fit 2 R indicated a highly fitted regression model for all four fishes tested, with highly significant (p<0.01) estimated regression coefficients. We also calculated the estimated range of chemico-microbiological parameters for each DP by using the confidence interval. This modified method of DP 3.3 was used to calculate the percent quality loss of initially four mentioned wet fish (L. rohita, P. sutchi, O. niloticus and T. ilisha) and later, huge other commercial wet fishes in different steps of their marketing and distribution channels country-wide. The modified fish loss assessment method has been come up as a useful field tool to quantify the qualitative loss of fish post-harvest.

Knowledge Management: Journal