Detection of lard in fish feed and optimizing the processing conditions for pelleted fish feed production using chemometric and response surface methodology
In order to save the cost of fish production, some small-scale farmers prefer to produce fish feed using inexpensive pelleting methods and ingredients. However, due to a lack of knowledge and expertise, the processing conditions of fish feed production are often neglected, and the basic ingredien...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English |
| Published: |
2022
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/104642/1/MOHAMED%20HANIFF%20HANAFY%20-%20IR.pdf |
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| Summary: | In order to save the cost of fish production, some small-scale farmers prefer to produce
fish feed using inexpensive pelleting methods and ingredients. However, due to a lack of
knowledge and expertise, the processing conditions of fish feed production are often
neglected, and the basic ingredient such as oil is deliberately replaced with cheaper
material such as lard. From a religious perspective, lard in any product is strictly
prohibited, especially for the Muslim community. This research thus intends to optimize
the processing conditions of the pelleting method using response surface methodology
(RSM) and also to detect lard as an adulterant in fish feed using fatty acid (FA) and
triacylglycerol (TAG)-based analyses separately, which are then integrated with
chemometrics. The optimum processing conditions were determined based on the
desired properties of bulk density, floatability, water absorption and water solubility
indices of the fish feed produced. For lard detection, sn-2 FA composition was coupled
with total FA composition to enhance the FA-based analysis by gas chromatographymass
spectrometry (GC-MS). Meanwhile, to improve the TAG-based analysis, thermal
analysis by differential scanning calorimetry (DSC) was combined with TAG
composition analysis by high-performance liquid chromatography (HPLC). These two
types of analysis (FA and TAG-based) were then incorporated with chemometric
techniques, namely principal component analysis (PCA), orthogonal partial least squarediscriminant
analysis (OPLS-DA), and orthogonal partial least square-regression
(OPLS-R). Results of RSM revealed that the combination of water temperature at 70 ºC,
mixing speed at 75 rpm, and mixing time of 5 min were the optimal processing conditions
in producing pelleted fish feed with the best quality. For lard detection, the enhanced-
PCA model exhibited a preferable distribution pattern of fish feed by differentiating them
into separate clusters without overlap. The OPLS-based prediction models constructed
from the most discriminating variables pre-defined by the enhanced-PCA also showed
good performances. The OPLS-DA model provided significant class discrimination
between lard adulterated and non-adulterated fish feed; meanwhile, the OPLS-R model
revealed a stronger relationship between the observed and predicted value of lard
percentage with the increasing value of the coefficient of determination (R2). The optimized processing conditions determined by RSM showed it was possible to produce
relatively good quality pelleted fish feed comparable to extruded fish feed. In addition,
the involvement of complementary analysis with chemometrics indicated that lard in fish
feed could be detected and quantified more effectively, and its relevant biomarkers could
also be discovered. |
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