Potato or scientifically named as Solanum tuberosum is a raw ingredient that contains high in enzyme polyphenol oxidase (Faisal. S et.al, 2013) which influence in the oxidative activity when the potatoes are cut causing it to become brown in color (Vitti M.C et. al, 2011). Potatoes are not encouraged to be sun-dried as the slow process of removal of water will induce the growth of fungal on the food's surface (Faisal. S et.al, 2013). Blanching treatments or osmotic dehydration method where the highly perishable foods such as fruits and vegetables or in this case, potato, are immersed in the concentrated solutions to produce intermediate moisture product. This pretreatment process helps to reduce processing time and helps to retain the properties
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This is to prevent the growth of microbial contamination and also to prolong the food’s shelf life. Moisture loss observed in potatoes is because of the intracellular spaces contain in its structure or its porosity. A study conducted by Wang. N and Brennan. J (1993), stated that there was a linear relationship between porosity and moisture content. According to Singh. F et. al (2014), one of the most significant effects on the porosity in potatoes is by the dehydration process. The removal of water during the rehydration process causes the cell to rupture due to stresses subjected to the cell membrane and cell wall of the potatoes. In addition, the stresses (usually generated by the water vapor) subjected to the cell membrane and cell wall will produce the pressure towards the food's cavity surfaces resulting in the increase of porosity of the product (Singh. F et. al, 2014). Therefore, it can be said that when the porosity increases, the removal of water also increases which lead to high in moisture loss of food product. According to Table 1, freeze-drying process causes the highest percentage of moisture loss (83.19%) in the potatoes followed by vacuum drying process (83.22%) and hot air drying process (82.77%). The percentage of moisture loss in freeze-dried potatoes are the highest because larger ice crystals form during the process of freezing which leads to larger pores formation …show more content…
M and Marinos-Kouris. D, 2003). The appearance of the rehydrated potatoes is shown in Figure 9 to Figure 11. The effect of the rehydration depends on the degree of cellular and structural disruption of the surface components of the potatoes during the drying process. In addition, the drying process will also rupture the dense structure in the potatoes which will lead to shrunken in size of the potatoes and reduced its hydrophilic properties (Krokida. M and Marinos-Kouris. D, 2003). The reducing in the hydrophilic properties of the potato results in the inability of the potato component to reabsorb water into its structure (Krokida. M and Marinos-Kouris. D, 2003) and decreasing the rehydration ratio. Results in Table 4 shows that freeze-drying method contributes in the highest rehydration ratio (5.49 ± 0.27) while hot air drying method resulted in the lowest rehydration ratio (1.98 ± 0.03). From the explanation above, it can be concluded that freeze-drying method causes less damage to the cellular and structural components of the potatoes and therefore increasing its ability to reabsorb water after undergo the drying process. This may be because of the low temperature used in the drying process. Hot air drying method has the lowest rehydration ratio because the heat involves in this drying
This is to prevent the growth of microbial contamination and also to prolong the food’s shelf life. Moisture loss observed in potatoes is because of the intracellular spaces contain in its structure or its porosity. A study conducted by Wang. N and Brennan. J (1993), stated that there was a linear relationship between porosity and moisture content. According to Singh. F et. al (2014), one of the most significant effects on the porosity in potatoes is by the dehydration process. The removal of water during the rehydration process causes the cell to rupture due to stresses subjected to the cell membrane and cell wall of the potatoes. In addition, the stresses (usually generated by the water vapor) subjected to the cell membrane and cell wall will produce the pressure towards the food's cavity surfaces resulting in the increase of porosity of the product (Singh. F et. al, 2014). Therefore, it can be said that when the porosity increases, the removal of water also increases which lead to high in moisture loss of food product. According to Table 1, freeze-drying process causes the highest percentage of moisture loss (83.19%) in the potatoes followed by vacuum drying process (83.22%) and hot air drying process (82.77%). The percentage of moisture loss in freeze-dried potatoes are the highest because larger ice crystals form during the process of freezing which leads to larger pores formation …show more content…
M and Marinos-Kouris. D, 2003). The appearance of the rehydrated potatoes is shown in Figure 9 to Figure 11. The effect of the rehydration depends on the degree of cellular and structural disruption of the surface components of the potatoes during the drying process. In addition, the drying process will also rupture the dense structure in the potatoes which will lead to shrunken in size of the potatoes and reduced its hydrophilic properties (Krokida. M and Marinos-Kouris. D, 2003). The reducing in the hydrophilic properties of the potato results in the inability of the potato component to reabsorb water into its structure (Krokida. M and Marinos-Kouris. D, 2003) and decreasing the rehydration ratio. Results in Table 4 shows that freeze-drying method contributes in the highest rehydration ratio (5.49 ± 0.27) while hot air drying method resulted in the lowest rehydration ratio (1.98 ± 0.03). From the explanation above, it can be concluded that freeze-drying method causes less damage to the cellular and structural components of the potatoes and therefore increasing its ability to reabsorb water after undergo the drying process. This may be because of the low temperature used in the drying process. Hot air drying method has the lowest rehydration ratio because the heat involves in this drying