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Oil and Fats as Raw Materials for Industry: An Introduction

Sonali Kesarwani1, Mukul Kumar1, Divya Bajpai Tripathy2*, Anjali Gupta2 and Suneet Kumar3

1Division of Forensic Science, School of Basic and Applied Sciences, Galgotias University, Greater Noida, Uttar Pradesh, India

2Division of Chemistry, School of Basic and Applied Sciences, Galgotias University, Greater Noida, Uttar Pradesh, India

3Forensic Science Laboratory, Moradabad, Uttar Pradesh, India

Abstract

Worldwide, fats and oils occupy major roles in nearly all industries like food, pharmaceutical, surfactants, biodiesel, agriculture, etc. The major renewable raw materials for the chemical industry are oils and fats, which are lipids. When ingested in sufficient quantities, they serve as a vital component of a healthy diet. Triacylglycerols (TAGs), also referred to as triglycerides, are essentially ester-linked glycerol moieties connected with three fatty acids that make up oils and fats. These fatty acids provide fats with useful properties. Because of the modification in lipids with improved nutritional and functional qualities, scientists and researchers have recently developed a growing interest in fats and oils. Triacylglycerols have a variety of properties and use depending on their structure and lipid composition. Therefore, altering the TAGs of lipids is a method for producing personalized lipids and expanding the range of their applications. Due to the detrimental health effects of trans fats, which are mostly brought on through partial hydrogenation, interesterification has become the dominant alternative strategy. This chapter provides a wide range of unprocessed fats and oils, along with information on their characteristics, classification, and historical evolution. In addition, the chapter emphasises the applications and difficulties in this field.

Keywords: Fats, oils, raw materials, saturated, unsaturated, applications, triglycerides

1.1 Introduction

"Fatty acids" (FAs) are molecules with long carbon chains in which the hydrogen atoms are connected to carbon atom bonds along with chains bearing carboxyl (-CO) as a functional group. Fatty acids are the building blocks of "fats" and "oils. "Saturated" fats are simple straight chains of carbon (C) atoms having alkanes, i.e., only single bonds between C-atoms, whereas unsaturated fats have alkenes or alkynes, i.e., double or more bonds. As a result, polyunsaturated fatty acids have more than two double bonds between C-atoms while monounsaturated fatty acids only have one double bond [1].

Natural fats and oils are mainly composed of triacylglycerols (TAGs), and the composition and molecular structure of TAGs differ from the physico-chemical and determines functional and nutritional properties of fatty acids, i.e., saturated, mono or polyunsaturated [2]. The suitability of fats and oils are usually determined by their physico-chemical properties. The use of the words "oil and fat" in most languages recognizes the property of being liquid or solid at ambient temperature as the basis for distinguishing between these two classes of products [3]. The molecular structure, melting and crystallization behaviour, and rheological properties of fats and oils are important for the rational design of lipid materials [4]. It is well known that the properties of fats and oils mainly depend on their triacylglycerol composition, i.e., the unsaturation degree and carbon chain length of the TAGs component fatty acid (FA) molecules [5].

Oils and fats are organic compounds with carboxylic acids as active elements. As a renewable source, oils and fats from plant seeds and animal tissues are used to manufacture petroleum products in industries [6]. Fats and oils are a "great source of energy (9 kcal/g) and essential fatty acids such as linoleic acid (18:2), linolenic acid (18:3), EPA (20:5) and DHA (22:6) to humans" [7]. Fats have a vital role in meat products, influencing organoleptic like palatability, texture and flavour, and technological aspects like cooking loss, emulsion stability, water holding capacity and rheological properties. In comparison to animal fats, vegetable oils have a higher ratio of unsaturated to saturated fatty acids and do not include cholesterol [8]. Being a source of important fatty acids and fat-soluble bioactive substances, vegetable oils and fats are a crucial part of the human diet.

Palm oil, sunflower oil, rapeseed oil and soybean oil are the four edible vegetable oils that are traded the most on a global scale. Interest in alternate sources of vegetable oils has developed due to the current demand for oils and fats for human consumption, with an emphasis on nutritious eating and new industrial uses [9]. Studies on the chemical and physical characteristics of oils and fats produced from distinctive oil plants have been done in order to identify substitute lipid sources with high nutritional value as well as to enhance commercial applications [10]. Due to the presence of carotenoids and chlorophyll pigments, vegetable oils are often clear and have a yellow or green colour [7]. Dietary sources of fats that play significant and varied roles in biological processes include vegetable oils and animal fats. Triacylglycerols are important components of oils and fats, and the profiles of various oils and fats varies significantly. For nutritional evaluation, quality assurance, and ensuring the safety of oils and fats, TAG profiles are required [11].

According to O'Brien (2009), "edible oils and fats consisting of esters of glycerine and fatty acids (>90%) are structurally distinguished from triglycerol based on their chain length, the position of the double and cis/ trans bonds as well as the relative ratios of saturated and unsaturated fatty acids, i.e., number and position of double bonds" [9]. In human nutrition, meats, fats, edible oils, fish, dairy products and nuts are the main sources of lipids in the human diet. Researchers have found that "dietary fatty acids play an important role in cholesterol metabolism and thus may be associated with cardio-vascular disease (CVD)" [12]. As we gain more knowledge about the relation between dietary fats and fatty acids and chronic diseases, particularly coronary artery disease (CAD), the significance of edible fats and oils in health and illness continues to develop [13].

In total, India grows nine different oil seed crops, seven of which are used to make edible oils, including sunflower, safflower, oilseed rape (mustard), niger, sesame, soybean, and peanut. Linseed and Castor, on the other hand, are non-edible oil seeds. Significant amounts of edible oil are also produced by maize germ, cotton seed, and rice bran [13]. Fats and oils are widely used in domestic and industrial settings, as well as being the most frequent contaminants in wastewater. Because they are typically removed by physical processes in sewage treatment plants, these substances are left behind in large quantities that are challenging to discard and process [13]. Fats and oils are significant organic components of municipal and industrial wastewaters, although it is unclear how they behave exactly during the treatment process [14]. Although recent advances in this sector have made it possible to remove a sizable part of oil from wastewater, biological treatment of oily wastewater is not well developed [15]. Anaerobic digesters of various designs have been researched for the treatment of sludge and oil simultaneously. For instance, anaerobic co-digestion of food waste, oils and fats with sewage sludge [16], long-chain fatty acids of oils and fats with municipal sludge [17], and aerobic co-digestion of sludge with oils and fats were also examined [18, 19].

1.2 Classification of Oils and Fats

Essential nutrients in a good diet include oils and fats. The terms oil and fat differ by the states of triglycerides, i.e., at room temperature, liquid triglyceride is termed as oils whereas at solid state it is fat [20]. Most commonly used oils and fats have long chain fatty acids, i.e., typically 8 to 20 carbon atoms, mostly having an even number of carbons; however, an odd number of carbon long chains is found mostly in animal fats. Such fatty acids contain -CH3 (methyl) group at one end and -COOH (carboxylic acid) group at other end. An ester bond of triacylglycerol is formed by the reaction of this carboxylic group with the hydroxyl (-OH) group present on the glycerol molecule [20].

Figure 1.1 Classification of fats and oils.

The three main groups of fatty acids (Figure 1.1) can be divided according to chain length:

1. Long-chain fatty acid
2. Medium-chain fatty acid
3. Short-chain fatty acid

1.2.1 Long-Chain Fatty Acid

Long-chain fatty acids (LCFAs) comprise 13 to 21 carbon atoms having an aliphatic end, as a result of hydrolysis of neutral triglycerides. Palmitate, stearate, and oleate are the three most abundant LCFAs present in the system where digestion takes place in the absence of oxygen termed as anaerobic digesters [21].

1.2.1.1 Long-Chain Saturated Fatty Acid

Saturated fats are solid at room temperature, which is why they are also called solid fat. It is primarily present in "foods of animal origin, like milk, cheese, and meat. Poultry and fish contain less saturated fat than red...