Changes

==== II. Impact of age on grains and grain-based food products ====

==== II. Impact of age on grains and grain-based food products ====

The age of food grains helps determine the quality as well as digestibility of food. ''Shuka dhanya'' (monocotyledons) and ''shami dhanya'' (dicotyledons) that are old /aged are easy to digest and are dry in property as compared to new ones. ''Nava anna'', or fresh, non-aged rice, millet, etc. increase ''kapha'' and are heavier than old grains. Charaka notes that all new and fresh grains are heavy and induce ''santarpana'', while aged grains are lighter to digest.

The age of food grains helps determine the quality as well as digestibility of food. ''Shuka dhanya'' (monocotyledons) and ''shami dhanya'' (dicotyledons) that are old /aged are easy to digest and are dry in property as compared to new ones<ref>Charaka Samhita Sutra Sthana 27/309 </ref>. ''Nava anna'', or fresh, non-aged rice, millet, etc. increase ''kapha'' and are heavier than old grains. Charaka notes that all new and fresh grains are heavy and induce ''santarpana'', while aged grains are lighter to digest.

Sharangdhara in Purva Khanda also talks of new and old grains and recommends six to twelve month-old grains to be used. Biochemical changes that help in digestion may be occurring after certain aging of grains. Per researchers (Seguchi, 1993), aging of flour and grains does enhance their functionality as ingredients for cakes and batter. Cereals can be stored for long periods without microbial spoilage. However, biochemical changes also occur during aging. There is great possibility that certain amino acids and phyto chemicals get stabilized in the grain which make them safe for consumption. Eventually, the grain respires, dry matter is lost and functional and nutritional aspects of the grain are altered. Age related changes have great influence on the viscosity of any batter made out of wheat-flour and the water-binding ability of the wheat flour (Shelke et al, 1992). In addition, the starch granule surface protein is found to increase up to three to four times with aging. However, prolonged aging is not recommended (Pomeranz et al, 1968). The moisture content of grains, the storage temperature and relative humidity have been shown to exert dramatic changes in the acidity, pH, free amino nitrogen, crude protein, and protein quality. Significant changes in soluble sugars and amylase contents of the grains have also been reported during storage at elevated temperature.   

Sharangdhara in Purva Khanda also talks of new and old grains and recommends six to twelve month-old grains to be used. Biochemical changes that help in digestion may be occurring after certain aging of grains. Per researchers (Seguchi, 1993), aging of flour and grains does enhance their functionality as ingredients for cakes and batter. Cereals can be stored for long periods without microbial spoilage. However, biochemical changes also occur during aging. There is great possibility that certain amino acids and phyto chemicals get stabilized in the grain which make them safe for consumption. Eventually, the grain respires, dry matter is lost and functional and nutritional aspects of the grain are altered. Age related changes have great influence on the viscosity of any batter made out of wheat-flour and the water-binding ability of the wheat flour (Shelke et al, 1992). In addition, the starch granule surface protein is found to increase up to three to four times with aging. However, prolonged aging is not recommended (Pomeranz et al, 1968). The moisture content of grains, the storage temperature and relative humidity have been shown to exert dramatic changes in the acidity, pH, free amino nitrogen, crude protein, and protein quality. Significant changes in soluble sugars and amylase contents of the grains have also been reported during storage at elevated temperature<ref> Zia-Ur Rehman, W.H. Shah. Biochemical changes in wheat during storage at three temperatures. Plant Foods for Human Nutrition 54: 109–117, 1999. </ref>.   

It is to be noted from various studies that the protein content of wheat grains and flour do not change significantly over time (Kim et al 2003). While protein quantity may not change, protein quality does. In one of the studies it was noted that total content of starch gets reduced after certain time when the grains are kept within controlled temperature. In India, wheat gets harvested in the months of March and early April. The atmospheric temperature varies from 25℃ – 45℃ in summer in different parts of India. The total starch content of the flour got decreased by 50 % when stored at 50℃ in comparison to the freshly harvested wheat grains. This is a significant change that occurs due to aging of wheat. If the starch content of wheat is reduced with time, aged wheat will have lower calorific value and lower glycemic index. It will also be easier to digest. Similar changes have been observed in rice after aging. Post harvest storage has, it has been observed, significant effect on eight known textural properties that are important to the sensory characteristics of cooked rice: adhesion to lips, hardness, cohesiveness of mass, roughness of mass, toothpull, particle size, toothpack, and loose particles. A difference is observed between ageing of rice flour and rice starch. It is evident that pasting properties of fresh and aged rice are different. It is also reported that the cell wall structure is decomposed by endo –xylanase during storage which led to the changes in amylograms of rice fours.  

It is to be noted from various studies that the protein content of wheat grains and flour do not change significantly over time (Kim et al 2003). While protein quantity may not change, protein quality does. In one of the studies it was noted that total content of starch gets reduced after certain time when the grains are kept within controlled temperature. In India, wheat gets harvested in the months of March and early April. The atmospheric temperature varies from 25℃ – 45℃ in summer in different parts of India. The total starch content of the flour got decreased by 50 % when stored at 50℃ in comparison to the freshly harvested wheat grains<ref>Seguchi, M. 1993. Effect of wheat flour aging on starch-granule surface proteins. J.Cereal Chem. Vol.70: 362-364.  </ref>  <ref> Shearer, G., Patey, A. L., and McWeeney, D. J. 1975. Wheat flour proteins: The selectivity of solvents and the stability of gliadin and glutenin fractions of stored flours. J. Sci. Food Agric. 26:337-344. </ref>. This is a significant change that occurs due to aging of wheat. If the starch content of wheat is reduced with time, aged wheat will have lower calorific value and lower glycemic index. It will also be easier to digest. Similar changes have been observed in rice after aging. Post harvest storage has, it has been observed, significant effect on eight known textural properties that are important to the sensory characteristics of cooked rice: adhesion to lips, hardness, cohesiveness of mass, roughness of mass, toothpull, particle size, toothpack, and loose particles<ref> sourced from : https://www.uark.edu/ua/uarpp/Publications/Sensory/Meullenet%20et%20al%202000%20Cereal%20Chem.pdf downloaded on 24/12/2016 </ref>. A difference is observed between ageing of rice flour and rice starch. It is evident that pasting properties of fresh and aged rice are different. It is also reported that the cell wall structure is decomposed by endo –xylanase during storage which led to the changes in amylograms of rice fours<ref> Shibuya, N. and Iwasaki, T. Eff ect of cell wall degradingenzymes on the cooking properties of milled rice and the texture of cooked rice. J Jpn Soc Food Sci Technol 31(1984) 656–660.  </ref>.  

These changes in physiochemical properties of grains exert their effect on digestibility of the food. It has been studied through experiments that the moisture content is higher in new grains indicating predominance of ''apa'' and ''prithvi mahabhuta'' which again tends towards ''santaparana''. Aging of rice has an impact on its glycemic index and glycemic load. New grain may have higher glycemic index than the older grain. Due to the effect of time on these food stuffs there are greater possibilities that certain amino acids and phyto chemicals get stabilized in the grain that make them safe for consumption.  

These changes in physiochemical properties of grains exert their effect on digestibility of the food. It has been studied through experiments that the moisture content is higher in new grains indicating predominance of ''apa'' and ''prithvi mahabhuta'' which again tends towards ''santaparana''. Aging of rice has an impact on its glycemic index and glycemic load. New grain may have higher glycemic index than the older grain. Due to the effect of time on these food stuffs there are greater possibilities that certain amino acids and phyto chemicals get stabilized in the grain that make them safe for consumption.  

''Navamadya''/fresh wine: New or fresh wines should not be consumed because they cause heaviness and create imbalances in all the three ''doshas'' while old wines promote circulation in the body, increase digestion, lightness and enhance taste in food. The effect of aging on tannins and resveratrol has been studied and shows significant difference between old and fresh wine. Aging results in altered and reduced phenolic contents in red wine. Anthocyanin tannin complexes can be formed which can stabilize the colour of red wines resulting in wines that are tasteless, fruity and less astringent after aging.  Oxidation reactions involving phenolics might also change the chemical and sensory profile of wines.  Oxygen in the air is always ready to react with unprotected juice or wine and many of the substances present get adversely affected by oxidation, producing unpleasant, bitter, off-odours and off-tastes. However, it is recognized that some degree of oxygenation may be beneficial for the formation of red wine, but the quality of white wines is generally impaired by excessive air exposure. As tannins and anthocyanins interact with oxygen, which diffuses during barrel storage, these compounds further polymerize and become less astringent. Red wines become lighter in colour, and proanthocyanidins and other polyphenolics eventually aggregate in larger molecules which accumulate as sediment over time at the base of the bottle. In contrast, white wines often deepen in colour, turning darker honey colours as they oxidize and age.   

''Navamadya''/fresh wine: New or fresh wines should not be consumed because they cause heaviness and create imbalances in all the three ''doshas'' while old wines promote circulation in the body, increase digestion, lightness and enhance taste in food. The effect of aging on tannins and resveratrol has been studied and shows significant difference between old and fresh wine. Aging results in altered and reduced phenolic contents in red wine. Anthocyanin tannin complexes can be formed which can stabilize the colour of red wines resulting in wines that are tasteless, fruity and less astringent after aging<ref> Scudamore-Smith PD, Hooper RL, McLaran ED (1990) Color and phenolic changes of Cabernet Sauvignon wine made by simultaneous yeast/bacterial fermentation and extended pomace contact. American Journal of Enology and Viticulture 41, 57-67 </ref>.  Oxidation reactions involving phenolics might also change the chemical and sensory profile of wines<ref> Bisson LF, Waterhouse AL, Ebeler SE, Walker MA, Lapsley JT (2002) The present and future of the international wine industry. Nature418, 696-699 </ref>.  Oxygen in the air is always ready to react with unprotected juice or wine and many of the substances present get adversely affected by oxidation, producing unpleasant, bitter, off-odours and off-tastes. However, it is recognized that some degree of oxygenation may be beneficial for the formation of red wine, but the quality of white wines is generally impaired by excessive air exposure. As tannins and anthocyanins interact with oxygen, which diffuses during barrel storage, these compounds further polymerize and become less astringent. Red wines become lighter in colour, and proanthocyanidins and other polyphenolics eventually aggregate in larger molecules which accumulate as sediment over time at the base of the bottle. In contrast, white wines often deepen in colour, turning darker honey colours as they oxidize andage <ref>sourcedfrom:http://www.academia.edu/8191054/Biochemical_Changes_throughout_Grape_Berry_Development_and_Fruit_and_Wine_Quality downloaded on 24/12/2016 </ref>.   

The phenolic compound present in a bottle of wine slowly changes as it ages. The most important component of wine is tannin which binds with proteins. High tannin containing wine inhibits saliva’s ability to lubricate mouth and imparts astringent feeling in mouth. Aged wine undergoes polymerization of tannins. This makes tannin sediments settle to the bottom of the container and lose its property to bind with proteins. Aged wines are very aromatic and possess fruity flavors.  

The phenolic compound present in a bottle of wine slowly changes as it ages. The most important component of wine is tannin which binds with proteins. High tannin containing wine inhibits saliva’s ability to lubricate mouth and imparts astringent feeling in mouth. Aged wine undergoes polymerization of tannins. This makes tannin sediments settle to the bottom of the container and lose its property to bind with proteins. Aged wines are very aromatic and possess fruity flavors.