Development of high protein and fibre fish snacks incorporated with coconut dregs by single-screw cooking extruder

Snacks are high in carbohydrates, sugar, salt, and fat but typically poor in protein and fibre content. Over-intake of high-calorie leads to a variety of health issues, including obesity and overweight, as highlighted in the National Health Surveys 2019 in Malaysia. As a result, there is a growing demand for healthy snacks, such as high-protein, highdietary fibre, and low-fat snacks. Extrusion cooking can fulfil this need by providing a wide range of flexibility for processing healthier formulations in extruded expanded snacks. Round scad fish was chosen as the protein source because of its economic value and is under-utilised despite its high nutritional values. Coconut dregs, a by-product of the coconut milk industry, are high in dietary fibre and often used as low-value products, included in the snack formulation. Therefore, the objectives of this study were to develop extruded fish snacks with high nutritional values using different types of starch (tapioca, sago, and corn) at different percentages of starch (50, 67 and 75%), to study the effect of moisture content (13% and 18%) and addition of coconut dregs (0-20%) on the extruded fish snacks, to optimise the barrel temperature and screw speed of single screw cooking extruder on the extruded fish snacks incorporated with coconut dregs using response surface methodology (RSM) and to study the stability of optimised extruded fish snacks in three different types of packaging (polypropylene, aluminium, nylon) during accelerated shelf life study at 55 °C for 30 days. The results of the study revealed that a higher amount of starch (75%) increased the expansion ratio (2.50 ± 0.15, 2.26 ± 0.15, 2.55 ± 0.13) and fracturability (6.56 ± 0.2, 6.62 ± 0.01, 6.56 ± 0.20 N) but decreased the bulk density (221.86 ± 8.03, 187.39 ± 14.39, 198.88 ± 7.26 kgm-3) and hardness of extrudates (62.17 ± 3.3, 23.52 ± 9.5, 69.54 ± 0.5 N) of tapioca, corn and sago starch extrudates, respectively. The findings indicated that the highest protein content (20.80%) was achieved with tapioca starch extrudates with 75% tapioca starch and 25% fish powder. This was followed by the inclusion of coconut dregs in the higher protein content of extruded fish snacks, which resulted in a lower expansion ratio, porosity, and crispiness but increased hardness and lightness. The addition of 20% coconut dregs contained the highest levels of total dietary fibre at feed moisture of 18%. The addition of coconut dregs increased the nutritional value of extruded fish snacks, but overall acceptance was low. Following that, the process optimisation by RSM was applied to produce high-protein and high-fibre extruded fish snacks with great potential for consumer acceptability in terms of hardness and fracturability properties. The optimal extrusion processing was achieved at 135 rpm for the screw speed and 180 °C for the barrel temperature. According to the hedonic score, consumers scored moderately like on the optimised high-protein and high-fibre extruded fish snacks incorporated with coconut dregs. For storage purposes, the physical and microbiological properties of highprotein and high-fibre extruded fish snacks incorporated with coconut dregs were stable during the 30 days of storage at accelerated temperature (55 ºC) in polypropylene, aluminium and nylon packaging, respectively. However, the peroxide value, which indicates the oxidation process, was significantly higher in polypropylene packaging than in nylon and aluminium packaging. The quality of the high-protein and high-fibre extruded fish snacks were maintained in the aluminium packaging for 5.6 months at an accelerated storage (55 ºC). In conclusion, this study may serve as a reference for the production of nutritious extruded snacks from fish and coconut dregs in the future. In addition, the study promoted usage of nutritious but underutilized round scad fish and low-value coconut dregs into a high value food product that will potentially help to boost consumption of healthy snacks among Malaysians.

Text 122567.pdf Download (1MB) Official URL or Download Paper: http://ethesis.upm.edu.my/id/eprint/18612

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