Laboratory Experiment No. 8
Group 2 – 3F1
Fabian, Felicia Kate
Francisco, Maria Sandy
Lagrazon, Paolo Martin
Lim, Jean Louis
Lugtu, Mari Rosario
Manucom, Jose Lorenzo
Masangcay, Jon Nikole
October 01, 2012
Food products are fundamentally mixtures of chemical compounds. That certain of these compounds may produce human toxicities has been known since before recorded history. Because human diets are normally composed of large numbers of differentf oods, only minute quantities of any speciﬁc toxic material are consumed.Thus dilution exerts a signiﬁcant protective effect against acute intoxication. Toxicants are substances which,upon ingestion, produce changes in homeostasis that are threatening to the normal function of the organism
Nitrogenous compounds are the most frequently implicated natural toxicants in foods. These compounds maybe grouped either according to gross manifestations or speciﬁc structural characteristics. Accordingly, vitamin-destroying enzymes, hemagglutenins, enzyme inhibitors, and many hepatotoxins, are of protein, peptide, oramino acid composition. Many of the hepatotoxins are also carcinogens. Enzyme inhibitors of a protein nature are of signiﬁcant concern because of widespread occurrence. The most common of these affect the pancreatic enzymes, trypsin and chymotrypsin ,and are found in legumes, eggs, soybeans, peas, most common beans, black eyed peas, lupine, and khesari, as well as in egg whites and potatoes. Protein inhibitors are often active against a variety of enzymes, although each molecule may possess a separate and very distinct binding site for each enzyme.
* To evaluate the levels of toxic substances namely alkaloids and oxalates in root crops. * To know the principle of alkaloid and oxalate determination. * To list the adverse health effects of these antinutrients found in food.
II. REVIEW OF RELATED LITERATURE
8.1 Antinutrients Level in Root crops
Determination of Alkaloids
Alkaloids are bitter tasting, water-soluble, and usually basic in nature (Libster, 2002). Alkaloids are a chemically heterogeneous group. They all contain nitrogen usually in a heterocyclic ring and many, if not all, are basic. Classification of alkaloids is based on the ring system present, e.g. pyridine, poperidine, tropane and isoquinone (Robinson, 1980).
Due to difference in their chemical structures, alkaloids have varying physiological effects (Robinson, 1980). The majority of plant alkaloids are known to have a narcotic, analgestic or sedative effect on the central nervous system and have played an important role in the development of human medicine (Libster, 2002)
Alkaloids are considered anti-nutritional because in general, they have a bitter taste which could limit food intake and have some toxic effects (Rodriguez and Mendoza, 1998). Amylase/protease inhibitors occur in the tubers of yams. Their presence could impair the digestion of starch and protein, thereby reducing the nutritional value of the tubers. Although the raw tubers contain varying levels of enzyme inhibitory activity, which could interfere with the digestion of carbohydrates and proteins. Simple processing methods like heat treatment has been shown to reduce the inhibiroty activity significantly. Therefore, these inhibitors may not interfere with digestion, if tubers are properly processed before consumption. (Libster, 2002)
Other anti nutritive factors include phenols, tannins, which are present in all tubers and bitter principles like alkaloids in yams. The alkaloids present in root crops include dioscorine, di-hydrodioscorine and both are nerve poisons. The alkaloids are soluble in water so that tubers containing high amount of alkaloids can be detoxified by prolonged soaking in water.
Root crops, in common with most plants, contains small amounts of potential toxins and...