International Journal of Aquaculture, 2016, Vol.6, No.19, 1
-
10
1
Research Article Open Access
Sensory, Microbiological, Biochemical and Physico-chemical Assessment of
Freshness and Quality of Fresh Lake Malawi Tilapia (
Chambo
) Stored in Ice
Fanuel Kapute
Department of Fisheries Science, Faculty of Environmental Sciences, Mzuzu University, P/Bag 201, Luwinga, Mzuzu 2, Malawi
Corresponding author Email
International Journal of Aquaculture, 2016, Vol. 6, No.19 doi
Received: 17 May, 2016
Accepted: 13 Oct., 2016
Published: 28 Nov., 2016
Copyright © 2016
Kapute, This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted
use, distribution, and reproduction in any medium, provided the original work is properly cited.
Preferred citation for this article
:
Kapute F., 2016, Sensory, microbiological, biochemical and physico-chemical assessment of freshness and quality of fresh Lake Malawi tilapia (
Chambo
)
stored in ice, International Journal of Aquaculture, 6(19): 1-10 (doi
Abstract
Sensory, microbiological, biochemical and physico-chemical methods were used to assess freshness and quality of fresh
Lake Malawi Tilapia (Local name: Chambo) to compare their effectiveness and reliability. Fresh Chambo samples were rejected by
the sensory panel after 16 days from day of catch with a strong linear correlation (P < 0.01, R
2
= 0.95) between sensory quality scores
and storage time in ice. Highest bacterial load of 1.6×10
7
cfu/g, cfu/cm
2
was observed on day 15 coinciding with sensory rejection
time. TMA-N and TVB-N for freshly caught fish was 0.7 and 5.1 mg/100g, which increased to 3.4 and 26.4 mg/100g respectively at
the time of sensory rejection also correlating with increased bacteria load in the fish. Initial pH of the fresh fish muscle was close to
neutral (6.47), and reached its lowest point (5.84) on day 16 which was sensory rejection time. Findings suggest that sensory
evaluation is reliable in the absence of the other methods. TMA-N is not a reliable method for assessing freshness quality of Lake
Malawi Tilapia due to insignificant readings. pH showed to be a quick freshness indicator with an understanding that muscle pH for
live fish is generally neutral and increases as deterioration of the quality of fish progresses in storage. Rejection of fish samples
before reaching unacceptable microbial limits in this study, underpins the need for using more than one method for accurate freshness
and quality assessments of fresh fish.
Keywords
Sensory; Microbiological; Biochemical; Freshness; Quality; Lake Malawi tilapia
1 Introduction
Fish is a highly perishable commodity (Liu et al., 2010). After death, a series of complex biochemical processes
set in culminating into rapid deterioration of fish freshness and quality over time (Huss, 1995). Wholesome
freshness in fish can therefore be guaranteed only when it is still alive in water (Ghaly et al., 2010). Quality also
involves safety aspects such as being free from harmful bacteria, parasites or chemicals (Gokoglu and Yerlikaya,
2015).
Due to the complexity in determining quality in fish, many indices have been used for the assessment of fish
quality such as microbiological, chemical, sensory analysis and physical assessment (Huss, 1995). Freshness and
quality assessment methods are broadly put into two categories namely, sensory and non sensory. While sensory
methods are useful for identifying products of very good or poor quality, these must be performed scientifically
under carefully controlled conditions to minimize effects of test environment, personal bias, etc. (Huss, 1995). On
the non sensory methods, TVB-N is the widely used indicator of spoilage but cannot be used as a freshness
indicator because it shows constant level during the first days of iced storage and does not reflect the mode of
spoilage (bacterial or autolytic) (Baixas-Nogueras et al., 2002). TMA-N like TVB-N analysis also does not reflect
the earlier stages of spoilage and are only reliable for certain fish species (Oehlenschläger, 1997). Microbiological
analyses on the other hand, are laborious, time-consuming, costly, and require skill in execution and interpretation
of the results (Huss, 1995). Accurate results in assessment of freshness and quality of fish can therefore be
obtained by correlating indices from various methods as a way of validation. This study assessed freshness and
quality of Lake Malawi Tilapia – a widely consumed commercial value fish in Malawi, using sensory,
microbiological, biochemical and physico-chemical methods to establish the reliability of these methods.
