Antinutritional factors in vegetables
Authors: Hanuman Ram1 G. S. Jat1 and Saroj Devi2
1Indian Agricultural Research Institute, New Delhi-110 012
2CCSHAU, Hisar, Haryana



INTRODUCTION

Vegetables are inseparable ingredient of the Indian palate.

India commanding 2nd position in area & production of vegetables globally with 9.08 m ha and 160.29 million tonnes

About 100 vegetables grown in India due to widely varying geo-agro-climatic privilege.

Vegetables are rich sources of minerals and vitamins besides calories.

Nutrition is a most important basic need, being a major determinant of health, labour productivity, and mental development.

But in most developing countries of the world, hunger and malnutrition are increasing due to population explosion, shortage of fertile land, and high food prices. Protein deficiency is widespread and has been cited as the most common form of malnutrition in developing Countries.

Along with it also contains many anti-nutritional & toxic compounds harmful to human & animal health.

LIST OF ANTI-NUTRITIONAL & TOXIC COMPOUNDS IN VEGETABLES

ANTI-NUTRITIONAL COMPOUNDS VEGETABLE SOURCE
Antitrypsin Factors/ trypsin inhibitors Legumes
Solanine / cyanogens Potato
Glucosinolates Cabbage
Lathyrogens Lathyrus spp.
Saponins Raw Spinach
Oxalates Leafy veg, Elephant foot Yam, Tannia, Taro
Cyanoglucosides Cassava
FuranoTerpenoids, Solanine & Trichothecen Potato
Xanthosomes Coco Yam
Carotoxin Carrot
ANTI-NUTRITIONAL COMPOUNDS VEGETABLE SOURCE
Pisatin, Phaseottin Raw French Bean
Bensofurans Celery
Vicines and Convicines Faba Beans
Ipomeamarone Raw Sweet Potato
Thioglycosides Cabbage & other crucifers
3-Furanoside Norditerpine ( Diosbulbin) Dioscorea bulbifera
Oxalates Amaranth, Spinacea oleracea
Raffinose Sweet potato
Cyanogens Squashes


These compounds may cause neurological disorders, kidney stones, elevated blood pressure and gastric disorders. Saponins present in soybean have the ability to haemolyse red blood cells (Tarade et al., 2006). Rhubarb contains oxalic acid, a toxic substance that in high concentrations can cause stomach irritation and kidney problems. It can also mess up with Calcium (Ca) metabolism and leach Ca from the body. In crucifers (raw cabbage), thiocynates and isothiocynates are present which cause goitre and hypothyroidism. The principle glycoalkaloids in potatoes are α-solanine and α-chaconine. They contribute flavour to potatoes but at higher concentrations cause bitterness and toxic to humans. Their natural function is probably to serve as stress metabolites or phytoalexins for the protection of potato when attacked by insects, fungi, etc. For food safety purpose, an upper limit for glycoalkaloid of 20 mg per 100 g of potato is generally accepted (Cantwell, 1996). Vadivel and Janardhanan (2005) reported nutritional and antinutritional characteristics of seven South Indian wild legumes. They carried out tests for mineral, amino acids, in vitro protein digestibility (IVPD) analysis and anti nutritional compounds like total free phenolics, tannins and the nonprotein amino acid L-DOPA. Other toxic compounds found in vegetables are Carotoxin (a nerve poison in carrot), Linamarin (Lima bean), Ca-oxalate (yam), Cassava (Cyanogenic glucosides).


The adverse effect of these factors can be minimized through post harvest processing, creating awareness, cooking, adopting cultural practices like earthing up (in potato) and breeding varieties having low antinutritional factors.


Genetic modification of potato and associated unintended effects on glycoalkaloids has been investigated in a number of studies. In some modified varieties, though significant increases were observed, the glycoalkaloid content remained below the recommended food safety limits.

Detoxification

Levels of cynaglucosides reduced by processing methods
Partial removal by boiling
Traditional Soaking of roots for a long period, repeated boiling and changing of water
Fermentation or Fermentation followed by heat treatment
Pounding fresh tubers followed by sun- drying is efficient method of detoxification.
Detoxification to different levels achieved by various processes of chip making from fresh cassava tubers.


References:

Cantwell, M. (1996). A review of important facts about potato glycoalkaloids. Perishables Handling Newsletter 87: 26-27.
Tarade, K.M., Singhal, R.S., Jayram, R.V. and Pandit, A.B. (2006). Kinetics of degradation of saponons in soybean flour (Glycine max) during food processing. Journal of Food Engineering 76: 440-445.
Vadivel, V. and Janardhanan, K. (2005). Nutritional and antinutritional characteristics of seven south Indian wild legumes. Plant Foods for Human Nutrition 60: 69-75.



About Author / Additional Info:
Ph D Scholar, Division of Vegetable Science, IARI, New Delhi - 110012