Professor Kelechi Mezu
Introduction to Biology – SCI 115
March 2, 2010
We use our sense of taste to differ if fruit is sweet or sour. That taste depends on the components in the fruit. Fruits contain fructose, acids, vitamin, starch, proteins, and cellulose. All of these components contribute to the taste of fruit. Fruits with high fructose levels tend to be sweeter whereas fruits with high levels of acid tend to be sour. Oranges however, have equal quantities of fructose and acids, leaving the taste a mystery. Raw fruits contain more acid but when ripened the acid decreases and the amount of sugar increases. Fruits such as bananas contain starch but gets converts to fructose when ripened. Until the starch is completely converted the fruit will have a sour taste. “Fruit development and ripening are unique to plants and represent an important component of human and animal diets.” (Giovannoni, 2004, para 1) The softening of fruit involves the partial breakdown of cell walls. Ripening involves the softening, increased juiciness and sweetness, and color changes of the fruit. Changes in fruit color involve changes in the expression of pigment biosynthetic gene. Ripening represents the shift from the protective function to dispersal function of the fruit. Ripening takes place with seed and embryo maturation. In dry fruits (cereals, nuts, dandelions) ripening consists of desiccation and is considered maturation. Ripening in fleshy fruits is designed to make the fruit appealing to animals that eat the fruit as a means for seed dispersal. Fleshy fruits are either climacteric or non-climacteric. Climacteric fruits produce a reparative burst with a concomitant burst in ethylene synthesis, as the fruits ripen. These include fruits with high degrees of flesh softening, like tomato, banana, avocado, peach etc. Ethylene is a major regulator of the ripening process. Inhibition of ethylene with inhibitors, transgenic approaches or mutants blocks ripening.
References: Giovannonni, J. (2004). Genetic Regulation of Fruit Development and Ripening. Retrieved February 26, 2010, from http://www.plantcell.org Healthy Eating: Easy Tips for Planning a Healthy Diet & Sticking To It (2001-2009), Retrieved February 26, 2010, from http://helpguide.org/life/healthy_eating_diet.htm McKeith, G. (2005). Good Food. Retrieved February 26, 2010, from http://www.enotalone.com