Chapter 3.2 Functional roles & interaction of food ingredients in the food system STARCH
In this Chapter 3.2, it is all about the starch including the processes such as gelatinization, pasting, gelation, retrogradation, the functionality of starch, factors affecting the flour functionality of starch and effect of additives or interfering agents to the starch's structure.
Gelatinization is a process of breaking down the intermolecular bonds of starch molecules in the presence of water and heat. When starch is heated in excess water, water migrates into the starch granules and caused swelling. Then, granule rupture, amylose will be released out and disperse in solution and produce a viscous colloidal state.
In the chocolate pudding experiment, when the chocolate mixture it is still hot, it is still in liquid form, it is called sol due to there is a lot of heat or vibrate energy. Gel formation occurs after gelatinization when the product is cooled because the molecules do not move as there is no more vibrate energy. Amylose molecules that have been left the starch granules during the gelatinization process are free to move about in a paste.
Retrogradation results in an undesirable and reduces food quality, it causes gritty texture and staling of bread. It is due to the result of amylose molecules rearranging in an orderly fashion. To avoid this happen, freezing can stop this process! However, it is a reversible process. For example, I reheat the rice, it will become soft back😮.
Finally, the process I newly learned in this chapter is Syneresis. It is when the water is squeezed out of the gel, the intermolecular interaction between amylose molecules become stronger and the gel shrinks, developing a gritty, crystalline texture and soggy. Retrogradation mostly happens in room temperature, while syneresis happens in cold, chilled or frozen products.
Through this chapter, I think the most important point that affects cookery products is the two main components in the starch structure which are amylose and amylopectin. Amylose is a linear structure, while Amylopectin is a branched structure. It affects the functionality or the physical and chemical properties such as gel formation, viscosity, clarity and etc...
High in amylose forms a firm gel because it is easy to realign or reassociate back while Amylopectin forms a weak film and soft gelling effect because of its branched structure is hard to realign back. High in amylopectin can form thick paste because the branched structure can trapped water in the starch granules.
Hence, all the factors that affect viscosity or functionality are all related to these two components, amylose and amylopectin. For example, types of starch, the concentration of starch, extent of heating, agitation and ingredients added.
Starch usually classified into cereal or roots and tubers. Most cereal contains amylose, while tubers contain higher amylopectin. Therefore, the usage of selected starch affects the properties of the product such as texture, clarity, viscosity. It is obvious to observe this theory during the practical time when we do the pudding and chilli sauce.
Then, the concentration of starch determines the viscosity of the product such as sauce or soup. When applying this in real life, my grandma always tells me when cook ABC soup or curry, she uses different potatoes such as Holland potato, US potato, China potato, she said it all depends whether what texture of the soup we want. For the soup, she would use china potato as it will not mess with the thickness of the soup, but if we want the thicker soup, she would use Holland potato😂. Due to the lower starch content concentration in China potato, the liquid is thinner or dilute, and low viscosity results.
Next, the extent of heating shows how the starch granules react when it is heated, it swells to gelatinisation until the maximum viscosity and then it breaks down, amylose release, and then undergo retrogradation and syneresis.
Besides, the other ingredients such as sugar, protein & fat and acid will have a negative impact on the viscosity of the product. For example, with the presence of citric acid or acid product will break down or hydrolysis the bonding hence it interfering the starch and disturb the intermolecular force.
In addition, if during prolonged heating there is vigorous stirring or agitation happen, the fragmentation will occur, pasty texture and weakened gel structure.
If thicken or gelling a heat sensitive product such as kiwi or strawberry, resistant starch, modified starch and crosslinking starch can be used. It is because they can controls granular swelling, high shear and tolerate high temperature.
If need to maintain a sharp, clean flavour important, such as in a fruit pie filling or glaze and also making a frozen product, substitute starch can be used because it increases peak viscosity, lower gelatinization temperature, minimizes syneresis, alter clarity, and increase water binding capacity😲.
Last but not least, in this chapter, I have learned how to choose or select the starch for the desired consistency for my end product. However, if evaluate myself in learning this chapter, I would give a 5 out of 10. It is because I feel like I am still not very familiar with the types of modified starch and I should observe more products that using modified starch in the market.
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| Rice Starch? |
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| Summary of this chapter |
Process
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| The gelatinisation of starch in excess water. |
In the chocolate pudding experiment, when the chocolate mixture it is still hot, it is still in liquid form, it is called sol due to there is a lot of heat or vibrate energy. Gel formation occurs after gelatinization when the product is cooled because the molecules do not move as there is no more vibrate energy. Amylose molecules that have been left the starch granules during the gelatinization process are free to move about in a paste.
Retrogradation results in an undesirable and reduces food quality, it causes gritty texture and staling of bread. It is due to the result of amylose molecules rearranging in an orderly fashion. To avoid this happen, freezing can stop this process! However, it is a reversible process. For example, I reheat the rice, it will become soft back😮.
Finally, the process I newly learned in this chapter is Syneresis. It is when the water is squeezed out of the gel, the intermolecular interaction between amylose molecules become stronger and the gel shrinks, developing a gritty, crystalline texture and soggy. Retrogradation mostly happens in room temperature, while syneresis happens in cold, chilled or frozen products.
FACTORS - Amylose & Amylopectin
High in amylose forms a firm gel because it is easy to realign or reassociate back while Amylopectin forms a weak film and soft gelling effect because of its branched structure is hard to realign back. High in amylopectin can form thick paste because the branched structure can trapped water in the starch granules.
Hence, all the factors that affect viscosity or functionality are all related to these two components, amylose and amylopectin. For example, types of starch, the concentration of starch, extent of heating, agitation and ingredients added.
Starch usually classified into cereal or roots and tubers. Most cereal contains amylose, while tubers contain higher amylopectin. Therefore, the usage of selected starch affects the properties of the product such as texture, clarity, viscosity. It is obvious to observe this theory during the practical time when we do the pudding and chilli sauce.
Then, the concentration of starch determines the viscosity of the product such as sauce or soup. When applying this in real life, my grandma always tells me when cook ABC soup or curry, she uses different potatoes such as Holland potato, US potato, China potato, she said it all depends whether what texture of the soup we want. For the soup, she would use china potato as it will not mess with the thickness of the soup, but if we want the thicker soup, she would use Holland potato😂. Due to the lower starch content concentration in China potato, the liquid is thinner or dilute, and low viscosity results.
Next, the extent of heating shows how the starch granules react when it is heated, it swells to gelatinisation until the maximum viscosity and then it breaks down, amylose release, and then undergo retrogradation and syneresis.
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| Viscosity profile of starch |
In addition, if during prolonged heating there is vigorous stirring or agitation happen, the fragmentation will occur, pasty texture and weakened gel structure.
Modified Starch
If thicken or gelling a heat sensitive product such as kiwi or strawberry, resistant starch, modified starch and crosslinking starch can be used. It is because they can controls granular swelling, high shear and tolerate high temperature.
If need to maintain a sharp, clean flavour important, such as in a fruit pie filling or glaze and also making a frozen product, substitute starch can be used because it increases peak viscosity, lower gelatinization temperature, minimizes syneresis, alter clarity, and increase water binding capacity😲.
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| Modified food starch |
Last but not least, in this chapter, I have learned how to choose or select the starch for the desired consistency for my end product. However, if evaluate myself in learning this chapter, I would give a 5 out of 10. It is because I feel like I am still not very familiar with the types of modified starch and I should observe more products that using modified starch in the market.
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