Essential Oils in Food Processing: Chemistry, Safety and Applications

Seyed Mohammed Bagher Hashemi, Amin Mousavi Khaneghah, Anderson de Souza Sant'Ana, Seyed Mohammed Bagher Hashemi, Amin Mousavi Khaneghah, Anderson de Souza Sant'Ana

• Publisher: Wiley-Blackwell
• Year: 2017
• Print ISBN: 9781119149347
• eBook ISBN: 9781119149378
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Food Science
• Index: Technology & Engineering

A guide to the use of essential oils in food, including information on their composition, extraction methods, and their antioxidant and antimicrobial applications

Consumers' food preferences are moving away from synthetic additives and preservatives and there is an increase demand for convenient packaged foods with long shelf lives. The use of essential oils fills the need for more natural preservativesto extend the shelf-life and maintaining the safety of foods. Essential Oils in Food Processing offers researchers in food science a guide to the chemistry, safety and applications of these easily accessible and eco-friendly substances.

The text offers a review of essential oils components, history, source and their application in foods and explores common and new extraction methods of essential oils from herbs and spices. The authors show how to determine the chemical composition of essential oils as well as an explanation of the antimicrobial and antioxidant activity of these oils in foods. This resource also delves into the effect of essential oils on food flavor and explores the interaction of essential oils and food components. Essential Oils in Food Processing offers a:

• Handbook of the use of essential oils in food, including their composition, extraction methods and their antioxidant and antimicrobial applications
• Guide that shows how essential oils can be used to extend the shelf life of food products whilst meeting consumer demand for "natural" products
• Review of the use of essential oils as natural flavour ingredients
• Summary of relevant food regulations as pertaining to essential oils

Academic researchers in food science, R&D scientists, and educators and advanced students in food science and nutrition can tap into the most recent findings and basic understanding of the chemistry, application, and safe us of essential oils in food processing.

1
Essential Oils and Their Characteristics

M.C.T. Duarte¹, R.M.T. Duarte¹, R.A.F. Rodrigues² and M.V.N. Rodrigues³

¹ Research Centre for Chemistry, Biology and Agriculture – CPQBA/UNICAMP – Microbiology Division, Campinas, São Paulo, Brazil

² Research Centre for Chemistry, Biology and Agriculture – CPQBA/UNICAMP – Chemistry of Natural Products Division, Campinas, São Paulo, Brazil

³ Research Centre for Chemistry, Biology and Agriculture – CPQBA/UNICAMP – Organic Chemistry and Pharmaceutical Division, Campinas, São Paulo, Brazil

1.1 Introduction

Essential oils are the main raw material for the aroma and fragrance, food and pharmaceutical industries. They have important biological activities that have been disclosed often in recent years. However, as the industry seeks its practical application and the development of new natural drugs containing active compounds from essential oils, there is an urgent need to standardise the plant material source. For this to become achievable, it is necessary to know the different factors that affect the production of essential oils by plants, in terms of its quantity as well as its quality.

It is known that plants produce essential oils as secondary metabolites in response to a physiological stress, pathogen attack and ecological factors. Also, in nature, the essential oils are recognised as defence compounds and attractors of pollinators, facilitating the reproduction of the vegetal species. The environmental variations, in turn, are also important in a plant’s ability to produce these compounds. Considering all of these factors, the main problems related to the cultivation of aromatic plants are due to variations that occur in quantitative and qualitative changes in the essential oils production. The main factors involved in the biosynthesis of essential oils by medicinal and aromatic plants are discussed in this chapter.

In order to optimise its commercial exploitation, the different factors involved in the production of essential oils must be taken into account, since the induction into its substance synthesis could affect the specific compounds of interest and their economic applications, as well as affecting the standard amount of produced oil.

1.1.1 Chemical Characteristics of Essential Oils

The designation essential oil originated from Aristotle’s era, because the of the idea of life‐essential elements — fire, air, earth and water. In this case, the fifth element was considered to be the soul or the spirit of life. Distillation and evaporation were the processes of removing the soul from the plant or essential oils. Nowadays, these oils are also known as volatile oils, but far from being soul, essential oils are a complexity of aroma’s composition. Those constituents of essential oils are generally derived from phenylpropanoid routes (Thayumanavan & Sadasivam, 2003).

The studies of those routes have disclosed the relevance of the aspect of physiology regulation, but certainly the isoprenoid exemplifies the major group of secondary metabolites in herbs, which exhibit extremely vast varieties of chemical structures and biochemical functions. Since primary metabolites exist in all plant cells that are qualified by division, secondary metabolites are there exclusive by accident, and are not essential for that herb. In contrariety to primary metabolites, secondary compounds vary extensively in their occurrence in those herbs and some may appear only in a unique or a few species (Krings & Berger, 1998).

Due to the connection of terpenoids in many pharmacological properties and their great value added specially for pharmaceutical, cosmetic and food industries, the isoprenoid route has been a spotlight for most related articles. Essential oils are nearly always rotational and have a high refractory index; they are sparingly soluble in water, usually less dense than water and liquid at room temperature, but there is some exception, as trans‐anethole (anise camphor) from the oil of anise (Pimpinella anisum L.), and they may be classified using different criteria: consistency, origin and chemical nature. As stated by their consistency, essential oils are classified as essences, balsams or resins. Depending on their origin, essential oils are natural, artificial or synthetic. Essential oils are aromatic chemical compounds that came from plant’s glands. Due to their volatility, flavour and toxicity, this class of compounds also plays significant aspects in the defence’s herbs, communication between plants and pollinator attractiveness (Muñoz‐Bertomeu et al., 2007; Thayumanavan & Sadasivam, 2003).

A lot of herbs can be view as being composed of a basic unit called isoprene or isopentane. Terms such as isoprenoid or terpenoid are employed concurrently. Many terpenoids are assemble of carbon atoms from acyclic disposition to a cyclic disposition by different chemical reactions, like, condensation, addition, cyclisation, deletion or rearrangements to be transformed in a basic unit, and generally, are very extensively diffused throughout the total plant kingdom. These compounds comprise a structurally varied class that can be splitted into the main and the minor terpenoids (Daviet & Schalk, 2010; Muñoz‐Bertomeu et al., 2006; Daniel, 2006; Thayumanavan & Sadasivam, 2003).

Biosynthesis of terpenes can occur in distinct sector of the herb, such as bark, flowers, fruits, leaves, roots, ryzomes, seeds and wood, and have all been described to concentrate them in different herbs. Terpenes that are main metabolites include carotenes, regulators of growth, proteins, quinones, polyprenols and the sterol, substitutes of terpenes with an alcohol functional group (Daviet & Schalk, 2010). These constituents are indispensable for preserving the membrane to keep the entirety of its structure, also to protection against light, and securing the maintenance of its biological functionality. Terpenes are a large class of chemical compounds, classified by the molecular weight, being monoterpenes, sesquiterpenes, diterpenes, seterterpenes, triterpenes, tetraterpenes and phytosterols amongst others (Thayumanavan & Sadasivam, 2003).

Monoterpenes are the major contributor of most important essential oils in nature. Since the monoterpenes (C₁₀H₁₆) are small molecules with two isoprene units, such as menthol and linalool, and they are lipophilic; they are promptly consumed through the skin. Synthetic compounds can be used to break down the problems come across with herbal products by creating actions for the construction of such molecules, regardless of the original species. Indeed, ways have been developed for most of the natural molecules, but, given their commonly complex spatial arrangements, the industrial production is not practicable for the majority of examples (Daviet & Schalk, 2010; Muñoz‐Bertomeu et al., 2006; Daniel, 2006; Thayumanavan & Sadasivam, 2003).

Characteristically, plant’s secondary metabolites are cumulated and stored in relatively huge quantities, which can be explained by their role as chemical signals or defence compounds. Terpenes are built up from the union of the two carbon units with five members each by condensation, isopentenyl diphosphate synonym isopentenyl pyrophosphate (IPP) and dimethylallyldiphosphate synonym dimethylallyl pyrophosphate (DMAPP), with different modes of structure formation, number of unsaturated bonds and type of linker groups. Not all terpenoids have a composition of their structures in the repetition of five carbon atoms, as can be habitual of them, considering that they are formed usually from isoprene as forming matrix (Daniel, 2006; Thayumanavan & Sadasivam, 2003).

Terpenes consisting of more than five isoprene structures appear in all herbs, and simpler terpenes (C₁₀–C₂₅) are mainly restricted in the phylogeny classification to the vascular plants/higher plants or, synonym Tracheophyta, while sesquiterpenes have been found broadly in division Bryophyta and in the kingdom Fungi. Monoterpenoids are colourless, distilled by steam, liquids insoluble in water with a typical scent, with a range of boiling points of 140 until 180 °C. Some of them have shown potentiality as insect plague management because they simply provide herbs with defences against insects that feed from it. M...

Table of contents

• Cover
• Title Page
• Table of Contents
• List of Contributors
• Acknowledgements
• Introduction
• 1 Essential Oils and Their Characteristics
• 2 Extraction Methods of Essential Oils From Herbs and Spices
• 3 Identification of Essential Oil Components
• 4 Chemical Composition of Essential Oils
• 5 Basic Structure, Nomenclature, Classification and Properties of Organic Compounds of Essential Oil
• 6 Antimicrobial Activity of Essential Oil
• 7 Bioactivity of Essential Oils Towards Fungi and Bacteria
• 8 Antioxidant Activity of Essential Oils in Foods
• 9 Mode of Antioxidant Action of Essential Oils
• 10 Principles of Sensory Evaluation in Foods Containing Essential Oil
• 11 Global Regulation of Essential Oils
• 12 Safety Evaluation of Essential Oils
• Index
• End User License Agreement