Potassium Analysis of Cooking Water and Selected Vegetables Before and After Leaching by Different Cooking Methods

The study aims to compare the potassium content of different types of cooking water (bore well, metro water and mineral water) and potassium rich vegetables (potato, yam, spinach and Amaranth gangeticus) before and after leaching by different cooking methods. The results illustrate that potassium content of the selected vegetables reduced significantly after leaching by different cooking methods. Maximum leaching of potassium from potato (75%) and yam (75%) was reported in pressure cooking. Maximum leaching of potassium from spinach (64%) and Amaranth gangeticus (87%) was reported in soaking and cooking method. Thus it is evident that processing vegetables by leaching removes potassium to such an extent it adds variety to the monotonous diet and makes most of the vegetables suitable for the dietetic management of the kidney disease. Potassium Analysis of Cooking Water and Selected Vegetables Before and After Leaching by Different Cooking Methods INTRODUCTION Food is the basic necessity of life which satisfies the physiological and social needs of human being. The nutritional approach which has dominated in most of the research works on food consumption views food and eating in relation to the nutrient composition of foods and their instrumental roles in the physiologic functioning of the human body (Shils, 2006). Vegetables form an essential part of the diet of both rich and the poor as majority of the Indian population is vegetarian (Bedi. R et al., 2006). In India a substantial proportion of the population, perhaps approximately 35%, follows a traditional vegetarian diet for many generations (Refsum. H et al., 2001). Vegetables are the major source of vitamins and minerals which are the chief regulators in metabolism in human beings (Shahnaz et al., 2003). Minerals are an important part of a healthy diet. Some minerals are necessary for human life and play very important roles in bodily functions. Nutrition professionals recommend that they should be consumed as part of a balanced diet, primarily as fruits and vegetables, rather than in the form of dietary supplements (Piotr Szefer and Jerome, 2007). Losses of vitamins and minerals during processing and cooking can occur either due to oxidation or by dissolving in water (Tapadia et al., 1995). One of the six general classes or kinds of nutrients found in all foods is water. Waterborne minerals are in ionic form and are easily absorbed by the gastrointestinal tract, it has been suggested that drinking water may be an important source of mineral intake (Arik et al., 2001). Potassium is a mineral involved in electrical and cellular body function. Elevated potassium is of special concern for patients with chronic kidney disease. In people with end stage renal disease high potassium foods must be limited so that potassium levels do not get too high and cause complications. Restricting potassium rich foods lead to reduced intake of fruits and vegetables leaving meat and fats as the main source of calories (Kamyar Kalantar et al., 2002). Evidence show that preparing vegetables by leaching removes potassium to such an extent it adds variety to the monotonous diet and makes most of the vegetables suitable for the dietetic management of the kidney disease. Hyperkalemia is a potentially life threatening situation as it can cause respiratory failure due to muscle weakness and sudden cardiac arrest. So in all chronic kidney disease patients with hyperkalemia a strict attention to potassium in the diet is required. Alternative choices should be provided either to limit foods that are high in potassium or to remove potassium from potato and other tuberous vegetables. Health care providers should be a food coach in balancing mineral restriction of patient while also trying to make them follow dietary guidelines for other medical conditions (John T. Daugirdas, 2011). If patients want to include some high potassium vegetable in their diet, leaching is recommended before using high potassium rich foods. The dietitians will be able to counsel on the amount of leached high potassium vegetables that can be safely included in the diet (National Kidney foundation, 2012). Renal dietetics practice centered on the multiple aspects of patient care, and wellness has developed during the recent times (Mary Kay Hensley, 2008). Data relating to potassium and other minerals present in potatoes and other vegetables cut in to various sizes before leaching and boiling are lacking. In an effort to increase variety, flexibility and compliance to the nutritional protocols for chronic kidney disease patients, this study investigates ways to optimize leaching of potassium from fresh vegetables. Studying the effect of leaching potassium from vegetables by different cooking methods will provide guidance to nutritionists developing diets and advise patients with compromised renal function on various ways to reduce potassium consumption. MATERIALS AND METHODS The present study involves pre-test post-test experimental design for estimating the potassium content of cooking water like bore well water, metro water and mineral water and potassium rich vegetables like potato, yam, spinach and Amaranth gangeticus before and after leaching by various cooking methods like soaking and cooking, normal cooking, double cooking, pressure cooking and microwave cooking. The different types of cooking water were analyzed for potassium content to see if the potassium content present in the water affects the leaching of potassium rich vegetables. 500 ml of all the water samples and 100g of all the raw vegetable samples were given for potassium analysis before cooking. Processing methods 100g of each vegetable were weighed and taken for each cooking method. The samples of raw vegetables namely potato and yam were peeled and cut in to evenly cube sized pieces. The green leafy vegetables were washed, cleaned and chopped evenly for processing. Metro water was selected for each processing method. For the soaking and cooking method the selected cut vegetables were soaked in hot water (50–60◦ C) overnight for 8 hours in 1:5 ratio (100g vegetables: 500ml of water). The soaked water was discarded and the vegetables were cooked for 10 minutes by sprinkling minimal amount of water. For the normal cooking and double cooking 100g of cut vegetables were added to the boiling water (100◦ C) and cooked for 10 minutes. In case of double cooking the same procedure was repeated again. For pressure cooking the vegetables were pressure cooked for 2 to 3 minutes with the same ratio of vegetable and water. The same ratio of each vegetable with water was cooked in microwave at 95 ± 2 C for 10 minutes. After cooking the water was discarded from all the samples and 100ml of each leached water samples and 100g of leached vegetables were given for