Investigating the possibility of modifying starch with the help of pulsed electric fields

Master's thesis in the field of agricultural engineering - food science and industry - food chemistry

general research

Abstract:

In this research, strong electric fields with short square pulses and a time scale between microseconds and milliseconds It was used for sanitizing liquid foods, and food was processed under environmental conditions or low temperatures and with low energy consumption, and it was used to modify potato, sago, tapioca and corn starch. (Process container) is applied in batch or continuously. When the electric current was passed through the food, the current was applied as a pulse but with a high field intensity for a very short time; In fact, the current was applied in a fraction of a second.

In this method, the sample must be able to pump and conduct electricity. Therefore, it is used for liquid food or liquid containing very small particles. In this research, we dissolved one gram of potato, sago, tapioca, or corn starch sample in 3% salt water and placed it in the treatment chamber of the (wire-cylindrical) Mizuno and Hori chamber and subjected it to a pulsed electric field for different periods of time and dried the sample removed from the electric field in a plate in an incubator at a temperature of 43 degrees Celsius and was written in tables and finally the characteristics of color, texture, microscopy and solubility in Water, modified samples were compared. In the end, it turned out that it can be effective and useful in all starch samples at 30 Hz and 20 kV in 5 minutes in all samples and in all starches at 30 Kv/cm voltage and 20 Hz frequency and time up to about 45 minutes in all samples we will gradually increase the color change.

Key words: strong pulsed electric fields, potato starch, sago, tapioca, corn

Introduction

Carbohydrates

Carbohydrates are the most abundant They are organic compounds found in nature and make up three quarters of the dry matter of the plant world. The name of carbohydrate to this class of substances is rooted in the era when it was thought that all the compounds belonging to this group are hydrated from carbon in terms of formula, and for this reason, the general formula YCx (H2O)y was also proposed for them. Although later it became clear that this formula is not true for all compounds belonging to this group, such as pectin or hemicellulose, but considering that these compounds had other common characteristics with the materials mentioned in the formula; The term carbohydrate has maintained its position and is still used. Due to their abundance and cheapness, carbohydrates provide most of the energy in the diet of most of the earth's inhabitants, and they play a very important role in feeding livestock and poultry, which are used by humans. Regardless of starch and glycogen, other polysaccharides (cellulose, hemicellulose and pectin) are almost unchanged from the human digestive system. This group, which is called under the name of dietary fibers, and they are mainly present in the walls of plant cells, although they seem to have no nutritional importance, but they actually play an important role in human nutrition and health. Because they create volume in the consumed food, which effectively helps to empty the material from the intestine. This feature causes the release of decomposed or non-decomposed and non-absorbable substances in the intestine, and their remaining in the intestine can cause irritation and failures in the digestive system and ultimately cause colon cancer. On the other hand, dietary fibers bind to bile acids and reduce their reabsorption, which can naturally reduce cholesterol in the blood. The amount of energy obtained from each gram of digestible carbohydrates is a quarter of a kilocalorie. In table one, the amount of carbohydrates of some foods is specified.

1-2-Monosaccharides:

Monosaccharides or monosaccharides can be formed from two main sources, one is glyceraldehyde and the other is dihydroxyacetone. It is for this reason that the prefix aldo or keto (which means having an aldehyde or ketone root) is used to name or specify them and then mention the number of carbons in the monosaccharide - such as aldohexose or ketohexose - in this way all monosaccharides can be identified under two headings or two groups of aldoses and ketoses.

Glucose is the most abundant monosaccharide in is nature The design or representation of the primary structure proposed for this substance by German scientist Emil Fischer was in the form of an open chain structure, i.e. containing an aldehyde agent in a free state. But considering that such a structure did not match the properties expected from a specific aldehyde compound, a closed structure that is formed by the reaction between an aldehyde agent and an alcohol agent present in the glucose molecule, thus forming a hemiacetal; It was suggested. On the other hand, since a ketohexose such as fructose did not show complete ketonic properties, it was accepted to perform a similar reaction between ketone and alcoholic agents and form a hemiketal with a closed structure in the case of such a sugar. If this reaction takes place between the aldehyde agent and the alcohol agent of carbon number 5, in this case, a heterogeneous ring or hexagonal heterocyclic ring with a structure similar to pyran is formed, and in this sense, the word pyranose (such as glucose pyranose) is used to specify it. If the reaction between the aldehyde agent and the alcoholic agent of the fourth carbon is carried out, in this case, a substance with a pentagonal ring structure such as furan is produced, which is referred to as furanose. Fructose is an example of such a compound and is called fructofuranose (of course, in fructose, the reaction between the present agent of carbon number 2 and the alcoholic agent of carbon number 5) generally, the pyranose structure is more common in solutions than the furanose structure.