Difference between blanching and parboiling

Key difference - blanching vs. parboiling

Although the terms blanching and parboiling are often used interchangeably, there is a difference between them. Blanching refers to the process of quickly dipping a food in boiling water and then quickly chilling it by then dipping it in ice water. Parboiling refers to a rapid boiling process, but not a rapid cooling process. Parboiling is often used to pre-cook a food that is then cooked in other ways, such as boiling, stewing, grilling, or stir-frying. Parboiled rice is the best example of parboiling products. Blanched food is an uncooked / mildly cooked product, while parboiled food is a pre-cooked product. This is the main difference between blanching and parboiling, and both cooking methods are used in both home cooking and the food industry, but are closely related. The purpose of this article is to identify the difference between blanching and parboiling.

Difference Between Blanching and Parboiling Infographic

What is blanching?

Blanching is a method in which food is boiled in 100 ° C hot water for a short time (1-2 minutes) and then immediately placed in ice-cold water to stop further nutrient loss. Some blanched vegetables may need to be squeezed before consumption to get the excess water out. It is often used for fruits and vegetables that are eaten raw or used to make salads. It is a technique used to inactivate color changing enzymes such as the polyphenol oxidase enzyme. Blanching can also be used to remove imperfections in the color and taste (bitterness) of food and to soften vegetables before frying.

Difference between blanching and parboiling

What is parboiling?

The word is often used when referring to parboiled rice. Typically, the purpose of parboiling is to cook an item in order to reduce the cooking time for the subsequent cooking process. The foods are placed in boiling water and cooked until they start to soften, then taken out before they are fully cooked. Parboiling is often used to partially cook or pre-cook a food that is then cooked in a different way. Parboiling is different from blanching in that it does not quickly cool the food with ice water after it has been removed from the boiling water. Raw rice, or paddy, is parboiled, and this process usually changes the color of the rice from white to pale reddish. About half of the world's rice production is parboiled, and the treatment is practiced in many parts of Asian and African countries such as India, Bangladesh, Pakistan, Malaysia, Nepal, Myanmar, Guinea, South Africa, Sri Lanka, Nigeria, and Thailand.

Key difference - blanching vs. parboiling

Parboiled rice

Difference between blanching and parboiling

Blanching and parboiling processes can have significantly different cooking conditions and some organoleptic properties of the end products. These differences can include

definition

Blanching: Blanching refers to removing the peel by scalding it or temporarily immersing it in boiling water.

Parboiling: Parboiling refers to cooking until partial boiling or boiling halfway through the cooking time.

purpose

Blanching: Blanching is used to improve the color of fruits and vegetables, to prevent enzymatic browning, to deactivate unwanted enzymes, e.g. odors (e.g. onion, cabbage) or to adjust the color of fruits and vegetables.

Parboiling: Parboiling is used to shorten the cooking time for the subsequent cooking process, to increase the nutritional value of the food (e.g. rice) and to increase the shelf life of the product. Nuts are parboiled to soften the shells so that they can be removed more easily; Rice is parboiled to improve texture, increase grind yield, and reduce head rice loss.

Processing steps

Blanching: Two basic steps in blanching are boiling and quick cooling.

Parboiling: Three basic parboiling steps are soaking, steaming, or boiling and drying.

Use of food additives

Blanching: Sometimes calcium is added to reduce the softening of vegetables and magnesium salt is added to prevent the breakdown of chlorophyll or the retention of the green color.

Parboiling: additives are not widely used.

Time and temperature conditions

Blanching: The food is cooked for 30 seconds to 1 minute and immersed in 0-4 ° C water. Hot water with temperatures in the range of typically 70 ° C to 100 ° C is used for cooking.

Parboiling: Depending on the type of parboiling, the food is cooked for 3-20 hours, e.g. B. traditional method or modified high pressure or steam generation method. Therefore, parboiling takes longer and hot water or high-temperature steam is used compared to blanching.

Cooking phase of the end product

Blanching: Only the outermost layer of the food is cooked.

Parboiling: All food is cooked and called a pre-cooked product.

Nutritional loss

Blanching: Some water-soluble and heat-sensitive nutrients can be destroyed. (e.g.: vitamin C, vitamin B)

Parboiling: Minimal nutrient losses can be observed. The nutritional value of parboiled rice is increased as the vitamins in the husk are transferred to the center of the rice grain during the parboiling process.

Chemical changes

Blanching: The deactivation of enzymes is the most important chemical change in blanching.

Parboiling: The starch content in parboiled rice gelatinizes and then decreases during storage. As a result of the gelatinization, alpha-amylose molecules emerge from the starch granule complex. The cooling during parboiled rice storage leads to retrogradation, in which amylase molecules reassociate with one another and form a tightly packed arrangement. This growth and development of type 3 resistant starch can act as a prebiotic and promote intestinal health in humans.

Examples

Blanching: This method mainly cooks fruits and vegetables.

Parboiling: This method mainly cooks rice and nuts.

To sum up, either when blanching or parboiling, the food undergoes cooking, and the difference is that blanched food is given an ice bath after cooking to prevent overcooking, a step that is not required when parboiling . This means that the food is fully or partially cooked after the parboiling process.

References

Desrossier, NW (1965). The Technology of Food Preservation, The AVI Publishing Company, 150-151.

Eliasson, AC (1986). Viscoelastic behavior when starch gelatinizes. Journal of Texture Studies, 17 , 253-265.

Food Protection Training Manual (PDF). New York City Department of Health and Mental Hygiene. 2010.

Miah, M., Haque, A., Douglass, M. and Clarke, B. (2002). Parboiling of rice. Part II: Influence of the hot soaking time on the degree of gelatinization of the starch. International Journal of Food Science and Technology, 37 (5), 539-545.

Pillaiyar, P. (1981). Parboiling of parboiled rice in the household. Kishan World, 8 , 20-21.

Image courtesy:

“Parboiled Rice” by Luigi Chiesa - Own work (CC BY-SA 3.0) via Commons Wikimedia

“Photo from blanching” by Foodista (CC BY 2.0) via Commons Wikimedia

About the author: Geesha

Geeshani holds a BSc (Hons) degree in Food Science and Technology and a Masters degree in Food and Nutrition. She is currently a PhD student at the Massey Institute of Food Science and Technology. Sharing what she has learned is one of her passions and she enjoys writing.