Why is spare rice valuable in the food sector?

Every year, India produces millions of tons of rice. Well! Thanks to modern science, our agriculture is at its peak. The produce is so huge that there is always a surplus or spare rice after domestic and export market use. This spare rice also includes the ones with poor quality or broken rice. So, what happens to all this rice?

Spare rice re-enters the food sector through the processed food industry. Rice takes many shapes and forms in this industry. It transforms into a stabilizer, a carrier, a sweetener, and a malt for beer. A series of processes and innovations make spare rice indispensable.

Spare rice for Ethanol

Ethanol, or ethyl alcohol, is a type of alcohol. It is a clear fluid that is soluble in water. It is a fermented product of the crops. Usually, crop waste from sugarcane and corn is the usual raw material for production. But rice can be a good alternative.

Ethanol production;

Ethanol production is a three-step process;

• Saccharification;
  • It needs enzymes that can break down starches into sugars.
  • The process starts with crushing the rice into small pieces. Then give it an alkali wash to remove all the protein. At pH 6 and 70 ℃ to 90 ℃, the α-amylase enzyme is added. After 2hr, the digestion is repeated with the second enzyme, glucosidase. The solution is filtered to separate the sugar.
• Fermentation;
  • This process converts the sugar to ethanol.
  • The next step is to add the yeast to the filtrate. The fermentation takes 4 days at a temperature of 30 ℃ to 40 ℃.
• Distillation; It is the process of increasing the concentration of ethanol. The yeast can tolerate up to 18% to 20% alcohol. With the increase in the amount of alcohol, the yeast starts dying. The distillation helps recover up to 99% of the alcohol from the solution. The solution is heated. Upon heating, the alcohol evaporates from the solvent. The vapors undergo condensation. The process led to the recovery of pure alcohol.

Industrial use

Ethanol has a wide range of uses in industries outside the food sector. But it is equally crucial and is gaining interest in the food industry. The uses can be listed as follows:

• Flavor industry; It acts as a medium for extracting the flavors from the spices and other ingredients. At the same time, it acts as a carrier for these flavors and helps with dispersion.
• Food color industry; It acts both as an extractor and carrier. The solvent helps extract the color from natural sources like flowers, plants, etc. It also takes care of even color dispersion.
• Beverage industry; Ethanol is crucial in alcoholic beverages like gin and vodka. Gin is a flavored spirit that is made by the redistillation of pure ethanol. Vodka is also a pure form of ethanol, mostly without flavors. But in many parts of the world, it is flavored with herbs, fruits, honey, and flowers.
• In food labs, ethanol is a must for the analysis of food. It acts as a solvent extractor, is used in pH indicators, and so on.

Spare rice as starches

Starches are very important for the food industry. It has many roles, from a stabilizer to a fat replacement. It has a range of applications.

The rice grains are made into flour to obtain the pure form of starch from the rice. This flour goes through a series of alkali and water treatments. It is to remove the protein from the flour. The protein gets extracted into the supernatant solution. The solution is drained or filtered out, leaving a mass of wet starch. This mass is further neutralized with acid and water washing, followed by filtration. The final product looks like a cake of starch. It is dried to form a powder.

Application of rice starch

The list of starch applications;

• It acts as a binder in confectioneries, dairy products, infant foods, processed meats, custards, and soups.
• The rice starch is helpful as a dusting agent in confectionaries. It prevents the candies from sticking to one another or the mold during processing.
• It can be used as a fat-mimetic in coatings for deep-fat frying, pastries, dairy, processed meat, soups, and sauces.
• They are used in frozen foods like low-fat ice cream and non-fat sauces as a fat substitute.
• The starch stabilizes canned food, ready-to-eat food, and food that undergoes rapid cooking.
• It acts as a crisping agent in cereals and extruded snacks.

Spare rice for glucose syrup or liquid glucose

Liquid Glucose is a clear, viscous liquid. It is sweeter than glucose. It is a one-stop solution for many products, such as;

• Hard candies, jelly, and gums
• Blended honey
• Bakery products, fillings, and toppings
• Canned fruits, juices, soft drinks, and health drinks
• Ice creams

There are specific properties that make it desirable, like

• It prevents crystallization, so it is ideal for products like honey.
• Liquid glucose can control the sugar bloom in hard-boiled candies.
• It makes candy less sticky and easier to handle while processing.
• The syrup provides a smooth mouthfeel.
• Reduce the amount of sweetness used in candy.
• The syrup adds viscosity to the medium.
• It increases the stability of frozen desserts.

Production of Liquid Glucose

Liquid glucose production is the process of breaking down starch into sugars. It can be divided into two major digestions; liquefaction and saccharification. The starches are broken down into dextrin during liquefaction by the enzyme glucosidase. Further, the dextrins are converted to glucose and maltose by the β-amylase enzyme during saccharification. The percentage of glucose and maltose may vary from 0 to 70%. The digested solution is cloudy and has many other solids. So, it is further refined into a clear, viscous syrup.

The processes and equipment used;

• Mixing tank; Mixing broken rice, liquefaction enzymes, and water takes place. The mixture is held in the tank for some time to allow the digestion process to start.
• Spray liquefaction; Injecting the solution into the tanks at high temperatures. This process completes the liquefaction, and starch converts to dextrin.
• Deproteinizer; It is a press filter that removes the protein and other solids from the dextrin solution.
• Saccharifying tank; The dextrin solution breaks down into sugars with the help of the enzyme. During this process, the desired concentration of glucose is achieved.
• The saccharified solution is a cloudy liquid. The solution is mixed with activated carbon, which makes the liquid transparent. Once clear, the solution is filtered to remove the carbon.
• The clear glucose liquid passes through a column of resins. It removes the impurities from the solution.
• Finally, the clear glucose solution evaporates, increasing the glucose concentration and making it a viscous liquid.

Rice in brewing

Rice takes part in brewing in two ways. It can be a pure rice malt beer or an adjunct. Pure rice beer contains 100% rice malt. An adjunct beer is a mixture of rice grits and malts from other grains like barley or wheat.

Rice malt beer

The production of a beer starts with making malt. Any malt-making process needs three steps; steeping, germination, and drying. The steeping is nothing more than soaking the grains in plenty of water. The grain absorbs up to 40% water at the end of the process. The germination activates the dormant enzymes already present in the kernels. The enzymes are essential for the brewing process. The malting aims to produce the enzymes. Once germination is complete, the kernels pass through the dryer. The activity of the enzyme stops at a high temperature. However, they can regain their movement under favorable conditions. This process is also known as Kilning.

Malting

In rice malting, the steeping happens at 20 ℃ to 30 ℃ for 24 to 48 hrs. Germination takes 4 to 8 days but can go up to 12 days in some varieties. The process requires a temperature of 20 ℃ to 30 ℃. The germinated rice grains require a kilning temperature of 45 ℃ to 70 ℃.

Brewing

The first important step in the brewing process is to make the wort. It involves mashing the ground malt with hot water. This process activates the enzymes that break down the starches into sugar. The slurry with the sugars is the wort. The wort is filtered to remove the solids. The enzymes are once again inactivated by boiling the wort. The next step is fermentation, which involves adding yeast to the wort and forming alcohol.

Rice wort production follows two methods, either decoction or infusion processes. In the decoction method, the top layer is decanted each time the mash reaches a specific temperature. In the case of the infusion method, the decoction is removed only once. It is boiled and re-added to the mash again. Then the mash is rested for a few minutes at different temperatures in increasing order. It can start at 50 ℃ until it reaches 77 ℃. Rice malt contains many enzymes. Each enzyme has its own working temperature and timing. The resting periods help each of these enzymes achieve that.

Rice as an adjunct in beer production

The adjunct improves the quality of the beer in terms of taste and flavor. The beer with the adjuncts tastes light and clean. It adds that extra sugar to the barley or wheat malt. The rice grits are mashed and added to the malt mash, which comprises 10 to 20% of the total mass. The resting temperature is 78 ℃ in this case. The process continues until all the starches turn into wort.

One major advantage of using rice as an adjunct is its cost-effectiveness. It can cut down the cost of the making by many folds.