Modified Starch


Modified Starch


Starch is a carbohydrate polymer and is widely used as a regulator and texture stabilizer. It's characteristics as a gelling agent, water retention agent, colloidal stabilizer, and thickener make its usage very common in the food industry. It is obtained from many plant sources such as maize, rice, potato, and wheat. But the insufficient performance of some functional characteristics leads manufacturers to look for different solutions to overcome these shortcomings such as poor processability and solubility in common organic solvents, retrogradation and syneresis, low shear stress resistance and thermal decomposition[1]. Starch modification is an industry full of possibilities where the sky is limit to form innovative starches which combine new functionality and value-added features as desired by the industry. Modified starches decrease retrogradation, gelling tendencies of pastes and gel syneresis. It also advances paste clarity and sheen, paste and gel texture, film formation and adhesion. Another purpose of modifying starch is to maintain the granules steady while processing and make starch suitable for the industrial usage of various foods. Modified starch is a processed starch derived from vegetables and grains for elevating the textural and structural properties of foods. The 'modified' word stands for physical, chemical, enzymatic modification, and genetic modification[2].

 

Physical modification of starch can decrease particle size and develop water solubility. 

These physical modification techniques are the treatment of native starch granules under different heat/moisture combinations, pressure, shear, and irradiation. This modification also covers mechanical erosion to change the physical dimension of starch granules.

Physical modification is preferred because it is easy, affordable and does not require any chemical and biological agents[3]. It can be achieved with the treatments such as dry heating, mild swelling and freeze-thawing. However, there are also new modification techniques demonstrated like Osmotic-pressure treatment, Pulsed electric field treatment, Corona electrical discharges, etc[5]. These days, chemical modification is giving its place to physical modification for the reason of demand for clean-labelled and less chemical used food products.

 

The chemical modification provides more functional properties comparing to physical and genetic modifications. It is obtained with derivatization like esterification, etherification, crosslinking, oxidation, cationization and grafting of starch. However, the concerns about the consumer and environmental problems that are created by these methods and the lack of new chemical modification methods that can substitute these harmful techniques; lead manufacturers to combine these methods with some physical modification methods like microwave, radiation and extrusion. These processing combinations help to obtain specific functional properties while shortening the modification time and improve production.

 

The Enzymatic modification is a modification method that we see as one of the final products in most of the food packages that are glucose syrup and high fructose corn syrup. 

One of the used enzyme for the modification is amylomaltases. It is applied to achieve a plant and chemical-free alternative to gelatine. In this application, the α-1,4 link between two glucose units breaks by the amylomaltases and afterwards creates a new α-1,4 link between them. The enzyme is required to be free of enzymatic elements which can produce unwanted destruction to the starch molecule. To perform this modification, the treated starch needs to contain amylose like potato, maize, wheat, rice and tapioca starch. 

 

Genetic modification is carried out in the plant pre-harvest period. With this method, it is possible to aim the specific enzymes in the plant and manipulate their biosynthetic pathway. The movement of these enzymes affects the reactivity, functionality, applicability in food processing. Genetic modification can be performed by conventional plant-breeding methods or by biotechnology. This modification method provides a way to design novel starches which can reduce environmentally dangerous post-harvest chemical and enzymatic modification[4].

.

CONTENT: Reyyan Nur BALOĞULLARI

.

.

 REFERENCES:

 

  1. Yifei Fan, Francesco Picchioni, Modification of starch: A review on the application of “green” solvents and controlled functionalization, Carbohydrate Polymers, Volume 241, 2020, 116350, ISSN 0144-8617, https://doi.org/10.1016/j.carbpol.2020.116350. (http://www.sciencedirect.com/science/article/pii/S0144861720305245)
  2. https://starchinfood.eu/question/what-is-modified-starch-and-why-is-it-modified/
  3. A.O. Ashogbon, E.T. Akintayo Recent trend in the physical and chemical modification of starches from different botanical sources: A review Starch - Stärke, 66 (1–2) (2014), pp. 41-57
  4. Chen Zhang, Seung-Taik Lim, Physical modification of various starches by partial gelatinization and freeze-thawing with xanthan gum, Food Hydrocolloids, Volume 111, 2021, 106210, ISSN 0268-005X, https://doi.org/10.1016/j.foodhyd.2020.106210.
  5. Bhupinder Kaur, Fazilah Ariffin, Rajeev Bhat, Alias A. Karim, Progress in starch modification in the last decade, Food Hydrocolloids, Volume 26, Issue 2, 2012, Pages 398-404, ISSN 0268-005X, https://doi.org/10.1016/j.foodhyd.2011.02.016.