Taylor / Hort Modifying Flavour in Food

1. Auflage 2007
ISBN: 978-1-84569-336-7
Verlag: Elsevier Science & Techn.
Format: EPUB
Kopierschutz: 6 - ePub Watermark

E-Book, Englisch, 296 Seiten

Reihe: Woodhead Publishing Series in Food Science, Technology and Nutrition

Ingredients and technologies which improve the flavour of food have always played a major role in food formulation. With increasing consumer demand for diet products, ready meals and natural ingredients, there is considerable pressure on food manufacturers to adapt ingredients in order to produce nutritious food. This important book provides professionals within the food industry with a comprehensive review of recent developments and research.The book begins with a comprehensive introduction followed by chapters on flavouring substances and the extraction of flavourings from natural sources. Chapters discuss technologies which improve flavour such as white biotechnology, the development of yeast flavour enhancers and the formulation of flavoursome low fat food. Further chapters cover techniques for flavour modification such as the controlled release of flavours, developments in sweeteners and masking agents for foods. The book concludes with chapters on the applications of new ingredients such as bitter blockers and masking agents.Modifying flavour in food provides a unique reference for manufacturers and scientists concerned with flavour modification. - Discusses adapting ingredients to meet consumer demand for nutritious food - Examines different technologies that improve flavour - Techniques for flavour modification are highlighted

Autoren/Hrsg.

Taylor, A. J.

Hort, J.

Leseproben

2 Flavouring substances: from chemistry and carriers to legislation
D. Baines,     Baines Food Consultancy Ltd, UK Publisher Summary
This chapter gives an account of how the flavor industry has developed its technology over the past century or so. The flavor industry has invested considerably in the development of encapsulating agents, which not only lock-in and protect the flavor, but can also be used to control the delivery of the flavor into a food matrix. The main encapsulating technologies used by the industry are Spray cooling, Coacervation, Melt extrusion, Molecular encapsulation and Yeast encapsulation. The creative skills of the flavorist take many years to hone and the creation of new flavors is one that is surrounded in mystery. “Putting nature back together” is a skill that is more complex now than it was 50 years ago because of the increased number of raw materials available. It not only requires experience, judgment, flair, and intuition but an extra spark of creativity to produce commercially successful flavors. The analytical technology used to discover the flavoring substances in foods can also be used to analyze the flavoring substances in a competitor’s flavors and the mass spectrometers of the flavor industry are being used more and more for this purpose. The appreciation of flavor is realized through our chemical senses of olfaction and gustation and, to a lesser extent, through certain molecules that interact with trigeminal nerves located in the mouth, throat, and nasal cavity. The trigeminal effect, or chemesthesis, is a minor but integral part of the flavor sensation involving the pain receptors that sense, for example, the heat from chilies, the cooling from peppermint, and the burning from horseradish. 2.1 The importance of olfaction in the appreciation of flavour
The appreciation of flavour is realised through our chemical senses of olfaction and gustation and, to a lesser extent, through certain molecules that interact with trigeminal nerves located in the mouth, throat and nasal cavity. The trigeminal effect, or chemesthesis, is a minor but integral part of the flavour sensation involving the pain receptors that sense, for example, the heat from chillies, the cooling from peppermint and the burning from horseradish. 2.1.1 Gustation
Gustation, or the sense of taste, is experienced through five types of interaction in the mouth; sweetness, sourness, bitterness, saltiness and ‘umami’, the latter being the Japanese word for succulence or deliciousness and elicited by the salts of glutamic acid, ribonucleotides and a few other taste active chemicals (Bell and Watson, 1999; Dewis, 2005). Taste responds primarily to non-volatile, water-soluble or saliva-soluble flavouring substances and serves a number of purposes. It monitors the quality of food through the sweet and umami taste receptors which respond to the presence of sugars and glutamate respectively. Detecting sugars determines carbohydrate quality and the supply of energy, and the detection of glutamate determines protein quality and the supply of essential amino acids for healthy metabolic functioning. The bitter and sour receptors serve a protective role and defend the body from noxious and poisonous substances and the regulation of sodium chloride in the bloodstream is facilitated by the salty taste receptor. 2.1.2 Olfaction
Our real ability to appreciate flavour, and to discriminate and understand the subtleties and nuances of foods and drinks, lies mainly with olfaction and is due to a quite amazing organ, the olfactory epithelium, which detects volatile organic chemicals in the environment and flavouring substances in food. This organ, located high in the nasal cavity, is a forward projection of the brain that interfaces with the outside world. It would have been one of the first organs to develop, even before the brain, and its original function would have been to detect chemical nutrients in an aqueous environment necessary for the survival of the organism. The olfactory epithelium has therefore had a very long time to evolve (Stoddart, 1999) and its ability to detect volatile organic chemicals is highly developed and tuned into the flavouring substances that are important in the foods we eat. It is estimated that the olfactory epithelium can detect and discriminate around 10 000 different smells through around 6 million receptor cells which are replaced by the body every 4–10 weeks (Mackay-Sim and Kittel, 1991; Key, 1999). These olfactory receptor cells each possess several hair-like structures called cilia which protrude into a mucous layer covering the olfactory epithelium. The cilia act as ‘docking ports’ for the volatile flavour substances that evaporate from the tongue and throat into the nasal cavity and absorb into the olfactory mucus during the process of eating and drinking. The flavour chemicals absorbing in the mucous layer couple with specialised olfactory binding proteins located in the ciliary membrane (Buck and Axel, 1991). A signal then passes to the olfactory bulb where it is amplified and the ‘signal to noise’ ratio minimised before being relayed to the olfactory cortex in the limbic brain where it is interpreted. The limbic system is the most ancient part of the brain and is also involved with emotion, mood, sexual behaviour, reproductive control and fear. Smells play a number of important roles through the limbic system such as neonatal bonding, flight response from prey, the selection of a mate and the monitoring of food. Smells can evoke memory and emotions, trigger fear, influence mood and are important for our enjoyment when eating. The ability of the olfactory epithelium to detect and interact with flavouring substances varies by many orders of magnitude and compared with gustation it is highly developed. If we compare the sensitivities of aroma and taste, our ability to detect sweetness through sugar is of the order of 3400 parts per million, the threshold level at which ordinary people start to detect sugar in water. If we relate this to time, which is easier to conceptualise, it is equivalent to approximately 1 second in an hour. By comparison, our ability to detect volatile flavouring substances is many orders of magnitude more sensitive and the flavouring substance with the lowest recorded threshold, maple furanone, has a threshold in water of 0.00001 parts per billion, which equates to a time scale of 1 second in 3.2 million years. Humans have an extraordinary ability to perceive and discriminate between thousands of volatile organic compounds and an astonishing sensitivity to certain molecules that in evolutionary terms have been an important aspect in the survival of the species. Such is the amazing chemistry, biochemistry and neurobiology of the olfactory epithelium; nanotechnology in action initiated by flavouring substances in food and other volatile organic chemicals in the environment. Our flavour senses are more complex than the simplistic overview described above and recent research has revealed that flavour perception is multisensory in nature, where one sensory input can modify the perception of another, showing that olfaction, gustation and chemesthesis are strongly interactive. A number of excellent texts are available describing olfaction, gustation and the multimodal relationship that exists between the senses in more detail, and the reader is directed to these for further information (Bell and Watson 1999; Taylor and Roberts 2004). 2.2 Flavouring substances in foods
Enormous progress has been made since the 1960s with the identification of volatile organic compounds in foods. In 1965 approximately 700 had been found but today the number of discrete volatile organic compounds detected in foods stands at over 7670; these are listed in the Nutrition and Food Research Institute of the Netherlands (TNO) publication website Volatile Compounds in Foods (VCF) (http://www.vcf-online.nl). The VCF register is the recognised world authority on the occurrence of volatile compounds in food and the latest version, 9.1, lists over 680 food sources in which flavouring substances have been identified. The compounds listed in the VCF have only been included if the validity of the identification has been authenticated by two methods of analysis, usually a retention time and a mass spectrum, and more than 105 700 individual occurrences are now registered in the database. Over 1000 discrete volatiles have been found in coffee and nearly the same number in beef. Many organic volatiles are ubiquitous across foods, while others are specific to a particular food group or even an individual food. It is this that makes the subject so fascinating and challenging for flavour chemists to identify which of the volatile organic compounds in foods are actually creating the flavour signals in the human brain that allow us to recognise the flavour of the food we eat. Not all volatile compounds found in food can be classified as flavouring substances because some do not possess distinctive aromas, while others have very high odour thresholds and are not detected among other lower threshold flavouring substances present in foods. Others may have undesirable aroma profiles and some volatile compounds found in food...