Tuesday, May 26, 2015

Functions of Gelling Agents in Food and Cooking: What Are the Alternatives for Vegetarians?

 

Hydrocolloids are large molecules that interact with water, and are defined as a type of mechanical mixture where one substance is dispersed evenly throughout water. Hydrocolloids are widely used in many food formulations to improve quality attributes and shelf life. Hydrocolloids can be either irreversible (single-state) or reversible. For example, agar, a reversible hydrocolloid of seaweed extract, can exist in a gel and solid state, and alternate between states with the addition or elimination of heat.

The two main uses are as thickening and gelling agents. As thickening agents, they find uses in soups, gravies, salad dressings, sauces and toppings while as gelling agents, they are extensively used in products like jam, jelly, marmalade, restructured foods and low sugar/calorie gels. The role of specific hydrocolloids for thickening and for gel formation is reviewed pinpointing specific applications in food formulations and for product development.

Hydrocolloids form gels by physical association of their polymer chains through hydrogen bonding, hydrophobic association and cation mediated cross-linking and differ from synthetic polymer gels, which normally consist of covalently cross-linked polymer chains. Hence, hydrocolloid gels are often referred to as “physical gels”.

What are the Alternatives for Gelatin

Though all hydrocolloids thicken aqueous dispersions, only a comparatively few gums form gels. In addition, the gels thus formed vary widely in gel character and texture. Hence, knowledge of the conditions is required for gelling of particular hydrocolloid dispersion; the characteristics of the gel produced and the texture it confers are very important aspects to design a specific food formulation. The important gums that find application in food as gelling agents include alginate, pectin, carrageenan, gellan, gelatin, agar, modified starch, methylcellulose and hydroxypropylmethyl cellulose. 

Each gelling agent has an optimum concentration range, with the corresponding specific methodologies and possible preparations. The manufacturers provide most of the parameters, but there is often a gap between the industrial application of a product and its practical use in the kitchen. These environments can be very different regarding factors such as equipment; amount of product used, and intended use of the product. One major difference is shelf life—the food industry requires its products to have a long shelf life, while the restaurant kitchen is characterized by immediacy and high turnover of raw materials and preparations. 

The principle characteristics and qualities of each of the seven types of gelling agent as well as the differences detected between them and the corresponding commercial products agents are summarized below.


Food Gelling Agents

1) HM Pectin

Used throughout the food industry in the production of jams, jellies, and marmalades. One of the most widely used gelling agents for pastry and desserts. Pectin is a natural part of the human diet, but does not contribute significantly to nutrition. The daily intake of pectin from fruits and vegetables can be estimated to be around 5 g (assuming consumption of approximately 500 g fruits and vegetables per day).

Pectin powder

Available in many different gelling strengths. Reacts differently in the presence of sugar and acids. Minerals can be added to improve gelling capability.

Tested product is one of the most widely used products in the food industry that is used to make standard gels.

Is Pectin Gelling Agent Suitable for Vegetarians?

Yes, it appropriate for vegetarians, it is found in fruit and vegetables. It has a high concentration in apples. Gelatin is not vegetarian but agar and pectin are. You can buy high-grade quality at low price from Amazon.com, Click here, classic pectin.


2) Gelatin

Because it is an animal product, gelatin is not suitable for vegans or vegetarians. When cooking or baking, it can sometimes be difficult to find a replacement that faithfully recreates the thickness and texture.

Functions of Gelling Agents in Food and Cooking

Gelatin - Emulsifier / Gelling Agent 

Gelatin has now been classed as food (made of animal skin and hoofs) in its own right. Remember, all types of gelatin are animal based and can be found in dairy products like yoghurts, plus many kinds of confectionery, jellies and other sweets.

Main characteristics

Creates soft and elastic gels that melt at low temperatures (melts in mouth). Food preparations containing gelatin can be frozen and defrosted.

Product varieties

Gelatin sheets and gelatin powder. The two types have different gelling strengths, which are measured in degrees of “bloom”.

Characteristics of product selected for testing

Gelatin sheets are easily dispersed into solution and do not produce residual taste in the final product. Gelatin powder may have some aftertaste.

What are the Alternatives for Gelatin?

Pectin can be used as a gelatin substitute, but is not generally recommended due to the acid and sugar required for proper gelling. It can be tricky to get the right flavor and texture. The Vegetarian Society suggests agar or carrageenan, both of which are derived from seaweed. Like gelatin, they are flavorless and only require water to work. They also are considered easier to use.


3) LM Pectin

Widely used in the food industry to produce jams, jellies, and marmalades with low sugar content.

Pectin powder

This is product is available in a range of gelling strengths, reacts differently with calcium, and can contain minerals to improve gel formation. Modified LM pectins are called LMA (amidated low methoxyl) pectins.

Tested product is the most pure and refined of the conventional LM pectins, which is ideal for preparing low sugar jams.


4) Kappa Carrageenan

Produces fast setting gels that can be prepared instantly. Gel texture is brittle and nonelastic at normal concentrations.

Kappa carrageenan powder

This product is available in many different gelling strengths.

Tested product is one of the most refined available, which contains potassium chloride to improve the gelling process. Final product has almost no residual taste of algae and is also clear – a rare combination.


5) Iota Carrageenan

Resulting gel is soft and elastic, and can be served warm (depending on the concentration used). Resulting gel is thixotropic-it can be broken and will reform. The texture is similar to gels made with gelatin.

Iota carrageenan powder

This product is available in a wide range gelling strengths.

Selected product is very easy to use as it contains sodium chloride, which improves gel formation.


6) Sodium Alginate

Used in spherification technique. Produces thermoirriversible gels that will not melt when heated.

Sodium alginate powder

There is a wide range of products available, with varying amounts of viscosity, gelling capability, and grade of refinement.

The product that we tested produced medium viscosity, and was easy to work with. Can be used for spherification, but leaves a slight residual taste of algae.


7) Agar-Agar

Creates a rigid and brittle gel that can withstand high temperatures. Preferred gelling agent for hot gels.

Agar-agar powder, produced by refining translucent algae filaments.

Agar-agar leaves a very light residual taste. Resulting gel is less opague than other gelling agents.


What is the Process of Gelling?

For the gelation of hydrocolloids, the three main mechanisms proposed are ionotropic gelation, cold-set gelation and heat-set gelation.

Ionotropic gelation occurs via cross-linking of hydrocolloid chains with ions, typically a cation mediated gelation process of negatively charged polysaccharides. Examples of such systems are alginate, carrageenan and pectin. 

Ionotropic gelation is carried out by either diffusion setting or internal gelation. In cold-set gelation, hydrocolloid powders are dissolved in warm/boiling water to form a dispersion which on cooling results in enthalpically-stabilized inter-chain helix to form segments of individual chains leading to a three dimensional network. Agar and gelatin form gel by this mechanism. Heat set gels require the application of heat to gel (eg, curdlan, konjac glucomannan, methyl cellulose, starch and globular proteins). It is usually only where heat setting is required in foods (eg, the use of starch in sauces). Heat setting mechanism occurs by unfolding/expansion of native starch/protein and their subsequent rearrangement into a network.



References:

Aguilera JM. 1992. Generation of engineered structures in gels. In: Schwartzberg HG, Hartel RW, editors. Physical chemistry of foods. New York: Marcel Dekker.

Bayarri S, Izquierdo L, Duran L, Costell E. 2006. Effect of addition of sucrose and aspartame on the compression resistance of hydrocolloid gels. Int J Food Sci Technol. [Cross Ref]

Burey P, Bhandari BR, Howes T, Gidley M. 2008. Hydrocolloid gel particles: formation, characterization and application. Crit Rev Food Sci Nutr. [PubMed]

Draget KI. Philips GO, Williams PA, editors. 2000. Alginates. In: Handbook of hydrocolloids. New York: Woodhead Publ Ltd.

Imeson, A. 2013. Thickening and Gelling Agents for Food. Springer. ISBN-10: 1461365775

Laaman, Thomas R. (Editor). 2010.  Hydrocolloids in Food Processing. Wiley-Blackwell; 1st edition

Moritaka H, Naito S, Nishinari K, Ishihara M, Fukuba H. 1999. Effects of gellan gum, citric acid and sweetener on the texture of lemon jelly. J Texture Stud. [Cross Ref]

Nishinari K, Zhang H. 2004. Recent advances in the understanding of heat set gelling polysaccharides. Trends Food Sci Technol. [Cross Ref]

Nussinovitch, Amos and Madoka Hirashima. 2013. Cooking Innovations: Using Hydrocolloids for Thickening, Gelling, and Emulsification. CRC Press

Puvanenthiran A, Goddard SJ, Mekinnon IR, Augustin MA. 2003. Milk-based gels made with κ-carrageenan. J Food Sci. [Cross Ref]

Roopa BS, Bhattacharya S. 2008. Alginate gels: I. Characterization of textural attributes. J Food Eng. [Cross Ref]

Thomas WR., Imeson A, editor. 1992. Carrageenans. In: Thickening and gelling agents for food. London: Blackie Academic and Professional.

Tosh S, Marangoni A, Hallet F, Britt I. 2003. Aging dynamics in gelatin gel microstructure. Food Hydrocolloids. [Cross Ref]

Urlacher B, Dalbe B., Imeson A, editor. 1992. Xanthan. In: Thickening and gelling agents for food. London: Blackie Academic and Professional.



Do you like sous vide and good food? Then you must have one of these, 9 Best Cookbooks for Sous Vide Cooking Technique

Friday, May 8, 2015

How Many Cups of Green Tea a Day for Weight Loss and Cancer Prevention?

 

Green tea is made from the leaves from Camellia sinensis that have undergone minimal oxidation during processing. Japanese green tea is made from the Yabukita cultivar of the tea plant. Unlike Chinese green teas, which are pan-fired, Japanese green teas are steamed giving them a more "vegetative" or "leafy" taste.

how-many-cups-of-green-tea-day-weight-loss-cancer-prevention

Green tea is rich in polyphenols, including catechins (and particularly epigallocatechin gallate-3, or EGCG), which reduce the growth of the new vessels needed for tumor growth and metastases. It is also a powerful antioxidant and detoxifier (activating enzymes in the liver that eliminate toxins from the body), and it facilitates the death of cancer cells by apoptosis. In the laboratory, it enhances the effects of radiotherapy on cancer cells.

Several claims have been made for the cancer preventive benefit effects of green tea consumption that is based on scientific investigation. This question is answered by two studies on patients in Japan, a country full of green tea drinkers. In a group of Japanese women suffering from breast tumors that had not yet metastasized, researchers discovered that those who consumed three cups of green tea a day had 57 percent fewer relapses than those who only drank one cup a day (1). In men with prostate tumors, daily consumption of five cups of green tea reduced the risk that their cancer would progress to an advanced stage by 50 percent (2).  

(1) Inoue, M., et al. 2001. Regular Consumption of Green Tea and the Risk of Breast Cancer Recurrence: Follow-up Study from the Hospital-Based Epidemiologic Research Program at Aichi Cancer Center (HERPACC), Japan. Cancer Letters 167, no. 2 (2001): 175-82.

(2) Kurahashi, N., et al. 2007. Green Tea Consumption and Prostate Cancer Risk in Japanese Men: A Prospective Study.  American Journal of Epidemiology 167, no. 1 (2007): 71-77.


Health Benefits of Green Tea against Cardiovascular Disease

Green tea drinking may be associated with a reduced risk of stroke. A 2013 Cochrane review of randomized controlled trials concluded that green tea consumption for 3–6 months appears to lower systolic and diastolic blood pressures a small amount (about 3 mmHg each). Additional analysis examining the effects of long-term green tea consumption on blood pressure has reached similar results. 


How Much Green Tea Should You Drink a Day to Lose Weight?

According to this research, "green tea for weight loss and weight maintenance in overweight or obese adults", there is no conclusive evidence that green tea aids in weight loss for overweight people. 


What is the Correct Way of Brewing and Serving Green Tea?

Steeping is the method of making a cup of tea; it is also referred to as brewing. In general, two grams of tea per 100 ml of water, or about one teaspoon of green tea per five-ounce (150 ml) cup, should be used. With very high-quality teas like gyokuro, more than this amount of leaf is used, and the leaf is steeped multiple times for short durations.

Green tea steeping time and temperature varies with different tea. The hottest steeping temperatures are 81 to 87 °C (178 to 189 °F) water and the longest steeping times two to three minutes. The coolest brewing temperatures are 61 to 69 °C (142 to 156 °F) and the shortest times about 30 seconds. 

In general, lower-quality green teas are steeped hotter and longer, whereas higher-quality teas are steeped cooler and shorter. Steeping green tea too hot or too long will result in a bitter, astringent brew, regardless of the initial quality, because it will result in the release of an excessive amount of tannins. High-quality green teas can be and usually are steeped multiple times; two or three steeping is typical. 

The steeping technique also plays a very important role in avoiding the tea developing an overcooked taste. The container in which the tea is steeped or teapot should also be warmed beforehand so that the tea does not immediately cool down. 

Keep in mind that the effect of green tea is quite remarkable. So why deprive yourself? Drink a cup today! ;-)

Please share this information to your friends.


Related Post: Broccoli also have scientific based anti-cancer properties. Avoid boiling broccoli. Boiling risks destroying sulforaphane and I3Cs. Do you want to know more? Learn; click here, How to Keep Cooked Broccoli Bright Green.


Other References:

Arab L, Khan F, Lam H. December 2013.  Tea consumption and cardiovascular disease risk. Am J Clin Nutr (Review) 98 (6 Suppl): 1651S–1659S. PMID 24172310. 

Hartley L, Flowers N, Holmes J, Clarke A, Stranges S, Hooper L, Rees K. June 2013. Green and black tea for the primary prevention of cardiovascular disease. Cochrane Database Syst Rev (Systematic Review and Meta-Analysis) 6: CD009934. PMID 23780706. 

Jurgens TM, Whelan AM, Killian L, Doucette S, Kirk S, Foy E. 2012.  Green tea for weight loss and weight maintenance in overweight or obese adults. Cochrane Database Syst Rev (Systematic review) 12: CD008650. PMID 23235664.

Khalesi S, Sun J, Buys N, Jamshidi A, Nikbakht- Nasrabadi E, Khosravi-Boroujeni H. September 2014. Green tea catechins and blood pressure: a systematic review and meta-analysis of randomized controlled trials. Eur J Nutr (Systematic Review and Meta-Analysis) 53 (6): 1299–1311. PMID 24861099. 

Larsson SC. January 2014. Coffee, tea, and cocoa and risk of stroke. Stroke (Review) 45 (1): 309–14. doi:10.1161/STROKEAHA.113.003131. PMID 24326448. 

Liu G, Mi XN, Zheng XX, Xu YL, Lu J, Huang XH. October 2014. Effects of tea intake on blood pressure: a meta-analysis of randomized controlled trials. Br J Nutr (Meta-Analysis) 112 (7): 1043–54. PMID 25137341. 

Peng X, Zhou R, Wang B, Yu X, Yang X, Liu K, Mi M. September 2014. Effect of green tea consumption on blood pressure: a meta-analysis of 13 randomized controlled trials. Sci Rep (Meta-Analysis) 4: 6251. PMID 25176280.

Servan-Schreiber, David. 2009. Anticancer: A New Way of Life. Viking. ISBN-10: 0670021644

Shen L, Song LG, Ma H, Jin CN, Wang JA, Xiang MX. August 2012. Tea consumption and risk of stroke: a dose-response meta-analysis of prospective studies. J Zhejiang Univ Sci B (Review) 13 (8): 652–62. PMID 22843186. 

Testmann,  Thomas. 2013. Green Tea: All You Need To Know - Green Tea History, Benefits, Types, Brewing and Serving. Thomas Testmann. ASIN: B00F0LCIWW



Proper diet is the foundation of a good health. Find out, what is the Ideal Human Diet According to the Latest Scientific Findings- 2015?

Saturday, May 2, 2015

You will Never Imagine these Beautiful Things are Food

 




The recipes are a result of extracting the essence of ingredients that play with sense and texture. In eating these foods, all the senses play their own roles in the appreciation of food. The food is experiential, a work of art and a show.

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