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Nutritional Quality of Edible Oils

Fats improve the taste and flavour of foods. Fatty foods satiate a hungry person fast because fats remain in the stomach for a longer period than either protein or carbohydrate (sugar) foods. Fats also carry essential vitamins like A, D, E and K. They also provide the body with essential fatty acids. Thus, fats have a very important role to play in human nutrition.

Spectrum of Fats and Oils

It is not just the butter and ghee that provide us the necessary fats. Vegetable oils, meat and fish too add fats in our diet. There is an array of vegetable oils available to human beings. They are groundnut, rapeseed, sesame, sunflower, safflower, soybean, niger, cotton seed, coconut, palm and rice bran oils. Ghee(butter fat), however, is the main animal fat utilized widely. The quality and composition of these oils vary as also the preference of people.

Post Harvest Technology

Introduction

The demand for edible oil has grown with the increase in world population. Improvement in living standards have made the population increase the consumption of oils and fats. It also has become more discriminating with respect to the oil quality. Oil producers, have to meet the increasing demand for edible oil, and improve product quality and variety as these have become major factors in the market-place.

Agriculture has been tuned through selective seed breeding and improved crop production practices to take care of the increasing demand. The emphasis has been to improve yield per hectare or tolerance to climatic variations. The ability to modify seed through traditional breeding and biotechnological approaches promises a revolution in agriculture. Using various approaches, not only quantitative improvement but also the qualitative changes especially fatty acid changes have been brought about. Customer support is needed for the genetically modified crops. A lot of controversy exists at present in accepting genetically modified crops. This aspect has to be studied in depth and needs to be resolved at the appropriate level as quickly as possible.

A prerequisite for the production of top quality oils and meals is a high quality raw material. Some attempts have been made to improve the physical characteristics of oils and meals through genetic, agronomic as well as through post production handling and processing technologies. The harvested quality grain should not be damaged during transportation, storage and processing. To produce a crude oil, the industry uses a number of processing steps, the application of which depends on the type of seed and the scale of the operation.

The purpose of Post Harvest Technology of oilseeds is to recover the maximum quantity of good quality oil and also make the deoiled cake useful as food or feed. Oil in oilseeds is located in spherosomes, which are the oil bodies (Salunkhe et al, 1992). When seeds are broken into small particles and the cells get ruptured the oil becomes available and is easily extracted. From the time of harvest, till the seeds are fed to the oil extracting machines, various processes are carried out to make good quality of oil available to the consumer apart from providing remunerative prices to the producer, namely, the farmer. The various steps involved in the oil extraction are proper harvest, drying, storage, seed cleaning, heat treatment and different types of machinery. The basic objective of every step in the post harvest technology is to minimize losses and to sustain or improve the quality of the product.

In addition to cultivated oilseeds, many other seeds and related plant products serve as sources of vegetable oils. They are obtained from large trees, shrubs or from different crops and their products. It may be the seeds or the husk, or the germ or other parts of the fruit or seed which are rich in oil. These are in general, referred to as non-conventional vegetable oil sources. They are highly important for the food/feed and non-food industries. Non- food and industrial uses are plenty.

But for the availability of these non- traditional oilseeds and their products, there would have been great pressure on the cultivated seeds. The products, mainly oil, help run our machines and protect them from getting rusted. Some of them protect our crops from pests and deseases. They even serve as beauty aids in the form of cosmetics. Some of them serve as sources of medicine for men and animals.

In recent years, some non-conventional/ non-edible oilseeds have become the raw material for biofuel/bioenergy. They have gained prominence, due to shortage of conventional oils. Seeds of more than 100 species occurring in the wild or cultivated are known to contain oil in considerable quantities. There is a vast scope for production and utilization of oil from these sources (Ambasta, 1986, Bhattacharya, 2002 and Vimal and Naphade, 1980).

In this chapter, the major non-conventional oilseeds of tree origin, by product oilseeds or other minor sources, are being dealt with. They are ricebran, corn, sal, mahua, jatropha, kokum, melia, rubber, mango kernel, kusum, simarouba, neem, karanj, crambe, moringa, tumba, jojoba and tobacco seed etc. Emphasis is given to the composition and quality of oil, cake and other plant parts. Their food, non-food and medicinal uses are presented. Oil extraction and related post harvest technological aspects are also discussed.

Groundnut

Groundnut roundnut is believed to have originated in Brazil and later spread to many countries all over the world. It is known to humanity since 950BC. Groundnut crop and its products have multiple uses. Being a leguminous crop it enriches the soil with nitrogen through symbiotic biological fixation by rizhobium. The economic product, groundnut in shell, contains the seeds, which are edible. The shell as well as the haulms serve as fuel and fodder. The seed oil serves as a good cooking oil while the cakes are good sources of protein for animals and even humans. Groundnut (Arachis hypogaea L,) belongs to leguminosae family and papilionacea sub family. It consists of two sub species each with two varieties. The first one hypogaea has the variety hypogaea (virginia group) and variety hirsuta kohla while the second one fastigiata has the variety fastigiata (valencia group ) and the variety vulgaris (spanish group). Hypogaea varieties are spreading types with branching and lack infloresence on the main stem. They are of longer duration and have fresh seed dormancy . Varieties of the fastigiata are of erect type with branching and flowering on the main stem also. The crop is of shorter duration than hypogaea types, but with little fresh seed dermancy.

The major groundnut producing countries of the world are China, India, Nigeria, U.S.A. Indonesia, Argentina, Sudan, Senegal and Myanmar. The cultivation is spread in tropical and sub-ropical regions. Groundnut is a self- pollinated crop and pollination takes place in the morning. After fertilization an elongated stalk namely peg develops which enters the soil, bends horizontally and swells to become a pod. Within the pod, two, three or four kernels are formed. The crop can be grown under rainfall conditions ranging from 50-125cm, with good distribution during flowering and pegging stages. Sandy loams, loamy soils, and black soils with good drainage are suitable for growing the crop.

Human being as a hunter has depended mostly on animal food and some fruits. With the progress of civilization, he settled down and

started agriculture around 7000-10,000 B.C. He started depending on plant grains to take care of his energy and nutritional requirements in addition to animal foods. Initially cereal grains must have mostly accounted for his staple food requirements. Taste and health requirements must have prompted him to diversify his crop production programme. It is this need that must have made him to cultivate oilseeds, fibre and other crops.

Oilseeds, thus, have been under cultivation since antiquity. Rapeseed and sesame have been described in the Indian Sanskrit writings of 2000 BC. Historically, extraction of oil seems to have been a batch process. Seeds kept in gunny bags or boxes were pressed to remove oil. The separated oil on clarification was used for food and non food purposes. The resulting cakes were utilized as animal feed or thrown away into fields which helped in improving the soil fertility. Human beings slowly discovered the uses of oil and other oilseed products for various food and non-food purposes.

There are several species of plants in the world whose oil can be utilized for human consumption. Though around 40 oilseeds are known, only around a dozen oilseed crops have become commercially important. There are ten seed crops and three tree crops. The seed crops are groundnut, rapeseed- mustard, sesame, soybean, sunflower, cottonseed, safflower, niger, castor and linseed. These are mostly annual crops. The three major tree oil crops are palm, olive and coconut.

APPENDIX – 1: Basic Information

Table 1: Spacing and plant population

5.1 Foliar nutrition of fruit crops

Foliar application of nutrients is gaining importance in horticultural crops in general and fruit crops in particular. The important criterion of the effectiveness of nutrient spray is the rate at which the foliar applied nutrients are absorbed by the leaves and translocated within the plant. For getting optimum yield, foliar fertilization should be carried out when the plant’s requirements are particularly high and the nutrient uptake through the plant roots is restricted. The restriction may be due to either plant or soil limitations.

4.1. Deficiency symptoms in different plant parts

Nutrients are important for growth and productivity of crops. Apart from the N, P, K, Ca, Mg and S, micronutrients such as Zn, Fe, Cu, B, Mo, Mn, Cl, etc. are also necessary for maintaining normal health and metabolism of plants. However, nutrient deficiency can lead to poor and stunted growth of plants resulting in poor yield performances. The depletion of nutrients from the soil is increasing due to adoption of modern agricultural technology through intensive and extensive cultivation of high yielding varieties. Nutrient deficiencies are very common in horticultural crops rather than in field crops.

Identification of nutrient deficiencies in crop plants through visual symptom is the cheapest diagnostic technique. When a nutrient element insufficiency occurs, below the critical level, visual symptoms may or may not appear, although normal plant development will be slowed. When visual symptoms occur, such symptoms can frequently be used to identify the source of the insufficiency.

Several diagnostic techniques are employed to asses the nutrient status of the crop. These are helpful in determining specific or multinutrient stresses and quantity of nutrients needed to eliminate the stress. Some of the techniques commonly used are:

Visual deficiency symptoms

Plant analysis

Rapid tissue testing

Diagnosis is the art of recognizing diseases or deficiency symptoms manifested from their symptoms, a scientific determination of a disorder based on critical scrutiny.

2.1 Diagnosis and prognosis

Diagnosis is the estimation of nutritional status of a plant during sampling, while prognosis is the prediction of possibility of deficiency impairing plant growth at stages in the growth cycle after the sample is taken. Diagnosis is based on comparison of nutrient concentration in plant parts (mainly leaves) with standard values related to physiological requirements of the plants. In diagnosis, mainly plant analysis is used. Prognosis is also based on critical concentration of same plant parts. This sometimes has led to confusion between these two concepts, which have been used with the same meaning. In contrast, to diagnosis, prognosis may be based on their leaf or soil analysis. The main difference between prognosis and diagnosis lies in the time between sampling and appearance of the influence on plant growth.

1.1. Introduction

The green revolution has led our nation from the state of deficiency to the state of self-sufficiency in food production. The grain production has increased substantially from around 50 million tonnes to about 220 million tonnes per annum. As per the latest estimates, annual fruit production is 44 million tonnes from an area of 3.72million hectares.

Depletion of nutrients, from the soil is steadily increasing due to the adoption of modem agricultural technology through intensive and extensive cultivation of high yielding varieties with chemically pure, micronutrients free high analysis fertilizers. So in recent years, the potentiality of many crops could not be exploited owing to the widespread nutrient deficiency observed in many parts of our country. With nutrient removals by crops exceeding the additions, there exists a perpetual negative balance. Consequently, nutrient deficiencies have multiplied in Indian soils and crops.

Phytobiotics are plant derivatives such as herbs, plant extracts or spices and have a wide range of activities such as stimulation of feed intake, growth and endogenous secretions in the gut. They act as immunomodulators resulting in decreased mortality and also have coccidiostatic, anti microbial, anthelminthic and anti-inf lammatory activities. Phytobiotics also possess hepatoprotective and hepatogenic properties, which tone up liver resulting in increased nutrient utilization and better performance. Herbs like Achyranthes aspera (Prickly Chaff Flower, Devil’s Horsewhip, Apamarga), Andrographis paniculata (Green chirayta, King of bitters, Kalamegha), Azadirachta indica (Neem), Boerhaavia diffusa (Spreading Hogweed, Punarnava), Eclipta alba (False Daisy, Bhringaraj), Ichnocarpus frutescens (Black creeper, Utpalagopa), Terminalia chebula (Black myrobalan, Haritaki). These herbs have hepatostimulant, hepato-protective, immunomodulatory and antioxidant activities (Sadekar et al., 1998; Manu and Kuttan, 2009; Michels et al., 2011, Dash et al., 2007). Further, they optimize digestion and metabolism resulting in better protein utilization, improved mucosal function and reduced cost of metabolic deamination. Andrographolide and 14-deoxy-11, 12-didehydro-andrographolide isolated from Andrographis paniculata inhibits free radical activities and lipid peroxidation. Inhibition of lipid peroxidation in meat prevents free radical production thereby preserving meat composition, colour and improvement in shelf life. In addition, it has been studied that a herb Terminalia chebula helps to reduce stress (Selvakumar et al., 2007).

Fats are rich sources of energy. Fats provide 2.25 times more available enrgy than carbohydrates. Fats also increase the palatability and reduce the dustiness of feed. Fats and fatty acids decrease the heat increment in the body. Fatty acids are also involved in number of physiological functions of the body. Recently, considerable interest has been shown on studies pertaining to dietary supplementation of polyunsaturated fatty acids (PUFA) in animal feed and their role in animal health and production.

An organic acid is an organic compound with acidic properties. The most common organic acids are the carboxylic acids, whose acidity is associated with their carboxyl group –COOH. However, sulphuric acids, containing the group –SO₂OH, are relatively stronger acids. Alcohols, with –OH, may also act as weak acids. Some other groups may also act as weak acids viz. thiol group and phenol group. In biological systems, organic compounds containing these groups are generally classified under organic acids. Some common organic acids are lactic acid, acetic acid, formic acid, citric acid, oxalic acid, uric acid, propionic acid and butyric acid. Organic acids have been used for decades in commercial compound feeds, mostly for feed preservation, for which formic and propionic acids are particularly effective. Since the ban of antibiotic growth promoters in many countries, organic acids have been used increasingly, not only because of their preservative qualities, but also for their nutritive properties. Organic acids and their salts are generally regarded as safe and have been approved by most member states of EU to be used as the feed additives in animal production.

Feed accounts for a significant cost of production in livestock and poultry. In case of poultry, it represents 65% cost of the production in broilers and 75% in layers. Presently the live stock industry faces a huge challenge due to the high cost of feed ingredients and shortage of the conventional feed ingredients. Over the years, efforts have been made to use unconventional feed ingredients. However, such feed ingredients have many anti nutritional factors that adversely affect the performance of livestock and poultry. Due to the presence of these incriminating factors, the unconventional feed ingredients are poorly digested in livestock and poultry. These poorly digested feed ingredients results in bacterial overgrowth, which becomes a potential substrate for bacterial fermentation leading to intestinal disorders and disease. Application of antibiotics and other anti-microbials help to overcome the ill effects. However, the ban on the use of sub therapeutic level of antibiotics in many countries has increased the relevance of use of exogenous enzymes in the feed of livestock and poultry. These exogenous feed enzymes improve the nutritive value of different feed stuffs, economize livestock and poultry rearing and reduce environmental pollution.

Prebiotic foods have been consumed for centuries, either as natural components of food, or as fermented food. However, interest in dietary use of prebiotics blossomed in the later 1800s and early 1900. Preliminary researches revealed that lactose had a profound effect on the pH of the caecal contents and intestine due to lactic acid fermentation resulting in enhanced calcium and phosphorous absorption. Further, it was also noted by several workers that inclusion of lactose in poultry diets resulted in better growth and reduced mortality.

A prebiotic can be defined as “a non digestible food ingredient that beneficially affects the host by selectivity stimulating the growth and/or activity of one or limited number of bacteria in the colon, and thus improves host health” (Gibson and Roberfroid, 1995). Based on this definition, Russell (1998) formulated the criteria according to which a substance can be a prebiotic. First, prebiotics are always feed ingredients that are not digested by the host, not or little used and/or metabolised as they pass through the upper portion of the intestinal tract, so they can reach the f lora of the large intestine. Secondly, they have to be able to serve as a substrate for one or more bacterial species with a potentially beneficial effect on the host. Finally they have to be able to cause a shift in the microf lora that improves the health of the host. In principle only non-digestible, fermentable feed components are prebiotics.