Food and nutrition.pdf

Wheat 217in -1 % of Indo-European populations). Much of the carbohydrate fractionof wheat is starch. Wheat starch is an important commercial product ofwheat, but second in economic value to wheat gluten. The principal partsof wheat flour are gluten and starch. These can be separated in a kind ofhome experiment, by mixing flour and water to form a small ball of dough,and kneading it gently while rinsing it in a bowl of water. The starch fallsout of the dough and sinks to the bottom of the bowl, leaving behind aball of glutenHealth ConcernsRoughly 1% of the population has coeliac (also written as celiac)disease-a condition that is caused by an adverse immune system reactionto gliadin, a gluten protein found in wheat (and similar proteins of thetribe Triticeae which includes other cuItivars such as barley and rye). Uponexposure to gliadin, the enzyme tissue transglutaminase modifies theprotein, and the immune system cross-reacts with the bowel tissue, causingan inflammatory reaction. That leads to flattening of the lining of the smallintestine, which interferes with the absorption of nutrients. The onlyeffective treatment is a lifelong gluten-free diet. While the disease is causedby a reaction to wheat proteins, it is not the same as wheat allergy.Production and Consumption StatisticsIn 2003, global per capita wheat consumption was 67 kg, with. thehighest per capita. consumption (239 kg) found. Unlike rice, whe~tproduction is more widespread globally though China's share is almostone-sixth of the world.While winter wheat lies dormant during a winter freeze, wheatnormally requires between 110 and 130 days between planting andharvest, depending upon climate, seed type, and soil conditions. Cropmanagement decisions require the knowledge of stage of development ofthe crop. In particular, spring fertilizer applications, herbicides, fungicides,growth regulators are typically applied at specific stages of plantdevelopment,For example, current recommendations often indicate the secondapplication of nitrogen be done when the ear (not visible at this stage) isabout 1 cm in size (Z31 on Zadoks scale). Knowledge of stages is alsointeresting to identify periods of higher risk, in terms of climate. Forexample, the meiosis stage is extrem.ely susceptible to low temperatures(under 4°C) or high temperatures (over 25°C). Farmers also benefit fromknowing when the flag leaf (last leaf) appears as this leaf represents about75% of photosynthesis reactions during the grain-filling period and as suchshould be preserved from disease or insect attacks to ensure a good yield.