Edible Oil Structuring

Concepts, Methods and Applications

Ashok R Patel

• Publisher: Royal Society of Chemistry
• Year: 2017
• Print ISBN: 9781782628293
• eBook ISBN: 9781788012225
• Edition: 1
• Topic: Biological Sciences
• Subtopic: Biochemistry
• Index: Biological Sciences

Driven both by real industrial needs and curiosity for fundamental research, edible oil structuring has emerged as a subject of growing interest with applications in real food systems. With contributions from leading research groups around the world, this book provides a comprehensive and concise overview of the field with special emphasis on the updates from the last 5 years. New insights into the mechanism of gelation in mono- and multicomponent gels are discussed for several categories of previously known structuring agents along with the potential food applications of some of these systems. In addition, use of alternative methods to explore structuring properties of hydrophilic biopolymers are presented with illustrative examples. Some new concepts such as bio-based synthesis of supergelators, foamed oleogels and use of innovative dispersion techniques give a broader picture of the current research in edible oil structuring.
This book will be of interest to students, academics and scientists involved in the research of edible oil structuring. It will be an important reference as it provides current information on the state-of-the-art of the field.

Section II

Structuring Units

CHAPTER 2

Biobased Molecular Structuring Agents

Sai Sateesh Sagiri^a, Malick Samateh^a,b and George John^a,b

^a Department of Chemistry and Biochemistry & Center for Discovery and Innovation (CDI), The City College of New York, New York, NY 10031, USA

^b Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, New York, NY 10016, USA
*E-mail:[email protected]

2.1 Introduction

Nature offers abundant biomass (as opportunities) in the form of carbohydrates, amino acids, proteins, fatty acids, triglycerides, waxes and nucleotides for designing structural and functional materials. Over the years, these functional molecules have been used in food, pharmaceutical, medicinal and cosmetic products. However, their use has hitherto been restricted to adjunct or supplementary roles in commercial products. In the contemporary market, few products are available with bioderived functional molecules as major constituents. For instance, food products such as margarine, shortening, spreads, chocolates, bakery and meat products possess either plant- or animal-derived fats as one of their major ingredients. These fats are largely responsible for differences in textural properties (consistency, spreadability, hardness, firmness, brittleness, etc.) and organoleptic properties (sensory attributes: appearance, smell, taste and touch). Since fat is a key component, food industries tend to use a wide range of fat sources for different applications. The major animal-derived solid fats currently being used in food products are butter, beef fat (tallow), pork fat (lard) and chicken fat. Besides animal sources, plant-derived vegetable oils containing saturated fatty acids, viz. coconut oil, palm kernel oil and palm oil, are also being used in many food products. Though the oils with saturated fatty acids are largely used, vegetable oils with lower saturated fat content such as canola oil, corn oil, cotton seed oil, olive oil, soybean oil and sunflower oil are also employed for some specific applications.

Saturated fatty acids contribute to the solid fraction of the oil. Therefore, the use of vegetable oils containing a high proportion of saturated fatty acids has become a common practice at the industrial level. The solid fraction of the total fat in an oil/fat source is improved by adding saturated fats to the liquid oils or modifying the unsaturated fatty acids present in the liquid oils into saturated or trans fats. The phenomenon of converting liquid oils to semi-solid fats is called oil structuring. In general, structuring is mainly affected by the solid component present in vegetable oils, which is commonly referred to as the structuring agent. At the industrial level, structuring of oils has been achieved mainly by either complete or partial hydrogenation methods. Despite the culinary and economic allure of these chemical treatments, food industries face several challenges in developing market-acceptable food products. These challenges include (a) achieving functional characteristics (texture, snap, appearance and stability), (b) minimizing costs, (c) avoiding adverse health implications (hydrogenation of oils yield trans fats, which are reported to be responsible for cardiovascular diseases) and (d) the ability to modify physical properties. Thus, there is a need for unremitting effort to develop new and improved functional and healthy fat materials for food applications. The solidification of vegetable oils using chemical modification (partial hydrogenation) yields undesirable trans fats. Thus, scientists have been trying to negate this problem by investigating methods such as mixing liquid oils with one or more external agents. These external agents or structuring agents can transform liquid oils to self-standing solid gels. Structured oils prepared via gelation are referred to as organogels, oleogels or lipid gels. Over the past two decades, various structuring agents have either been discovered or designed for vegetable oil structuring. These molecular gelators offer a potential alternative to the commercial/traditional edible oil structuring processes viz. complete/partial hydrogenation.

Molecular gelation resembles the mechanistic entrapment of liquid molecules within a fat crystal network as observed in butter, lard, margarines and shortenings. The direct replacement of solid fats with structured fats is technically challenging because the mouthfeel and textural properties of food products are mainly due to the saturated fats. Structured vegetable oils (e.g. oleogels, emulsions) possess the functionality of fats with the nutritional profile of vegetable oils (high unsaturated fatty acids, low saturated fatty acids and free of trans fats). As a result, structured oils can act as solid fat mimicking agents (fat replacers, fat alternatives) in shortenings, margarines, ice creams, chocolates, cookies, bakery products and meat products. In general, oil leakage and textural problems are the major concerns with the use of unsaturated fats or liquid oils in food products. These concerns can be answered by using structured vegetable oils as they have shown significant reduction in the oil leakage or oiling out and improvement in the textural properties of food products.¹ In the recent past, formulations containing structured oils have also been explored as delivery vehicles for drugs, nutraceuticals and other active ingredients.^2,3 The structuring strategies for vegetable oils and the possible applications of the resulting structured vegetable oils are schematically represented in Scheme 2.1. The development of bioderived structuring agents has enhanced the scope of molecular gels, emulsions and related formulations in food, pharmaceutical, cosmetics and petrochemical industries towards green and sustainable value added products.

Scheme 2.1 Structuring strategies of vegetable/edible oils and the possible applications of structured oils.

2.2 Vegetable Oil Structuring: Chemical Methods

2.2.1 Hydrogenation

The successful creation of innumerable confectioneries, chocolates, bakery and dairy-based food products can be attributed to a simple reaction: hydrogenation of edible oils, invented in 1902.⁴ This technology was patented in 1906 by the British company Joseph Crossfield and Sons and established the protocol for hydrogenation of edible oils.⁵ This technology was introduced in the USA by Procter and Gamble (Cincinnati, OH) in 1911.⁵ Then it was recognized that animal fat (butter) could be substituted with vegetable oils by formulating margarine. However, the technology for hydrogenation of edible oils was not extensively used until the introduction of margarine to the market by food industries in the 1950s. Margarine was found to have a longer shelf-life, higher melting point, lower cost and better organoleptic properties compared to butter and lard. Since then, various kinds of margarines, shortenings, vegetable spreads, creams and pastes have been synthesized using edible oils. The main objective of hydrogenation is to improve the oxidative stability of liquid oils by reducing the concentration of unsaturated fatty acids, which are prone to oxidation at room temperature. Hydrogenation changes the physical properties of liquid oils by converting unsaturated fatty acids to saturated fatty acids, which are stable and solid at room temperature, thus extending their application.⁶ Hence, the addition of hydrogen results in the reduction of unsaturated fatty acids to saturated fatty acids, which enhances the van der Waals interactions between the aliphatic chains to form solidified oils. The conversion of oleic acid (monounsaturated fatty acid) to stearic acid (saturated fatty acid) is schematically shown in Figure 2.1. The chemical process for hydrogenation of vegetable oils involves the addition of hydrogen atoms to the unsaturated carbons of fatty acids in the presence of a catalyst, namely, nickel, copper, platinum, or palladium. Nickel has been used most extensively at the industrial level owing to its good catalytic potential, selectivity, reusability, less influence on unsaturated fatty acid oxidation and cost effectiveness compared to platinum and palladium. Hydrogenation mainly depends on oil temperature, hydrogen pressure, rate of mixing, reaction time, ca...

Table of contents

• Cover
• Title
• Copyright
• Contents
• Section I: Introduction
• Section II: Structuring Units
• Section III: Structuring Units: Crystalline Particles and Self-assembled Structures
• CHAPTER 5 Structuring Edible Oil Phases with Fatty Acids and Alcohols
• CHAPTER 6 Gelation Properties of Gelator Molecules Derived from 12-Hydroxystearic Acid
• Section IV: Structuring Units: Polymeric Strands and Network
• CHAPTER 8 Proteins as Building Blocks for Oil Structuring
• CHAPTER 9 Oleogels from Emulsion (HIPE) Templates Stabilized by Protein–Polysaccharide Complexes
• CHAPTER 10 Cereal Protein-based Emulsion Gels for Edible Oil Structuring
• Section V: Edible Applications
• CHAPTER 12 Edible Applications of Ethylcellulose Oleogels
• Section VI: Functional Colloids from Structured Oils
• Subject Index