Michael Bom Frøst

Molecular Gastronomy: A New Emerging Scientific Discipline

The science of domestic and restaurant cooking has recently moved from the playground of a few interested amateurs into the realm of serious scientific endeavor. A number of restaurants around the world have started to adopt a more scientific approach in their kitchens,1–3 and perhaps partly as a result, several of these have become acclaimed as being among the best in the world.4,5 Today, many food writers and chefs, as well as most gourmets, agree that chemistry lies at the heart of the very finest food available in some of the world’s finest restaurants. At least in the world of gourmet food, chemistry has managed to replace its often tarnished image with a growing respect as the application of basic chemistry in the kitchen has provided the starting point for a whole new cuisine. The application of chemistry and other sciences to restaurant and domestic cooking is thus making a positive impact in a very public arena which inevitably gives credence to the subject as a whole. As yet, however, this activity has been largely in the form of small collaborations between scientists and chefs. To date, little “new science” has emerged, but many novel applications of existing science have been made, assisting chefs to produce new dishes and extend the range of techniques available in their kitchens. Little of this work has appeared in the scientific literature,2,3,6–9 but the work has received an enormous amount of media attention. A quick Google search will reveal thousands of news articles over the past few years; a very few recent examples can be found in China,(10) the United States,11,12 and Australia.(13) In this review we bring together the many strands of chemistry that have been and are increasingly being used in the kitchen to provide a sound basis for further developments in the area. We also attempt throughout to show using relevant illustrative examples how knowledge and understanding of chemistry can be applied to good effect in the domestic and restaurant kitchen. Our basic premise is that the application of chemical and physical techniques in some restaurant kitchens to produce novel textures and flavor combinations has not only revolutionized the restaurant experience but also led to new enjoyment and appreciation of food. Examples include El Bulli (in Spain) and the Fat Duck (in the United Kingdom), two restaurants that since adopting a scientific approach to cooking have become widely regarded as among the finest in the world. All this begs the fundamental question: why should these novel textures and flavors provide so much real pleasure for the diners? Such questions are at the heart of the new science of Molecular Gastronomy. The term Molecular Gastronomy has gained a lot of publicity over the past few years, largely because some chefs have started to label their cooking style as Molecular Gastronomy (MG) and claimed to be bringing the use of scientific principles into the kitchen. However, we should note that three of the first chefs whose food was “labeled” as MG have recently written a new manifesto protesting against this label.(14) They rightly contend that what is important is the finest food prepared using the best available ingredients and using the most appropriate methods (which naturally includes the use of “new” ingredients, for example, gelling agents such as gellan or carageenan, and processes, such as vacuum distillation, etc.). We take a broad view of Molecular Gastronomy and argue it should be considered as the scientific study of why some food tastes terrible, some is mediocre, some good, and occasionally some absolutely delicious. We want to understand what it is that makes one dish delicious and another not, whether it be the choice of ingredients and how they were grown, the manner in which the food was cooked and presented, or the environment in which it was served. All will play their own roles, and there are valid scientific enquiries to be made to elucidate the extent to which they each affect the final result, but chemistry lies at the heart of all these diverse disciplines. The judgment of the quality of a dish is a highly personal matter as is the extent to which a particular meal is enjoyed or not. Nevertheless, we hypothesize that there are a number of conditions that must be met before food becomes truly enjoyable. These include many aspects of the flavor. Clearly, the food should have flavor; but what conditions are truly important? Does it matter, for example, how much flavor a dish has; is the concentration of the flavor molecules important? How important is the order in which the flavor molecules are released? How does the texture affect the flavor? The long-term aims of the science of MG are not only to provide chefs with tools to assist them in producing the finest dishes but also to elucidate the minimum set of conditions that are required for a dish to be described by a representative group of individuals as enjoyable or delicious, to find ways in which these conditions can be met (through the production of raw materials, in the cooking process, and in the way in which the food is presented), and hence to be able to predict reasonably well whether a particular dish or meal would be delicious. It may even become possible to give some quantitative measure of just how delicious a particular dish will be to a particular individual. Clearly, this is an immense task involving many different aspects of the chemical sciences: from the way in which food is produced through the harvesting, packaging, and transport to market via the processing and cooking to the presentation on the plate and how the body and brain react to the various stimuli presented. MG is distinct from traditional Food Science as it is concerned principally with the science behind any conceivable food preparation technique that may be used in a restaurant environment or even in domestic cooking from readily available ingredients to produce the best possible result. Conversely, Food Science is concerned, in large measure, with food production on an industrial scale and nutrition and food safety. A further distinction is that although Molecular Gastronomy includes the science behind gastronomic food, to understand gastronomy it is sometimes also necessary to appreciate its wider background. Thus, investigations of food history and culture may be subjects for investigation within the overall umbrella of Molecular Gastronomy. Further, gastronomy is characterized by the fact that strong, even passionate feelings can be involved. Leading chefs express their own emotions and visions through the dishes they produce. Some chefs stick closely to tradition, while others can be highly innovative and even provocative. In this sense gastronomy can be considered as an art form similar to painting and music. In this review we begin with a short description of our senses of taste and aroma and how we use these and other senses to provide the sensation of flavor. We will show that flavor is not simply the sum of the individual stimuli from the receptors in the tongue and nose but far more complex. In fact, the best we can say is that flavor is constructed in the mind using cues taken from all the senses including, but not limited to, the chemical senses of taste and smell. It is necessary to bear this background in mind throughout the whole review so we do not forget that even if we fully understand the complete chemical composition, physical state, and morphological complexity of a dish, this alone will not tell us whether it will provide an enjoyable eating experience. In subsequent sections we will take a walk through the preparation of a meal, starting with the raw ingredients to see how the chemical make up of even the apparently simplest ingredients such as carrots or tomatoes is greatly affected by all the different agricultural processes they may be subjected to before arriving in the kitchen. Once we have ingredients in the kitchen and start to cut, mix, and cook them, a vast range of chemical reactions come into play, destroying some and creating new flavor compounds. We devote a considerable portion of the review to the summary of some of these reactions. However, we must note that complete textbooks have failed to capture the complexity of many of these, so all we can do here is to provide a general overview of some important aspects that commonly affect flavor in domestic and restaurant kitchens. In nearly all cooking, the texture of the food is as important as its flavor: the flavor of roast chicken is pretty constant, but the texture varies from the wonderfully tender meat that melts in the mouth to the awful rubber chicken of so many conference dinners. Understanding and controlling texture not only of meats but also of sauces, souffles, breads, cakes, and pastries, etc., will take us on a tour through a range of chemical and physical disciplines as we look, for example, at the spinning of glassy sugars to produce candy-floss. Finally, after a discussion of those factors in our food that seem to contribute to making it delicious, we enter the world of brain chemistry, and much of that is speculative. We will end up with a list of areas of potential new research offering all chemists the opportunity to join us in the exciting new adventures of Molecular Gastronomy and the possibility of collaborating with chefs to create new and better food in their own local neighborhoods. Who ever said there is no such thing as a free lunch?

Sensory perception of fat in milk

The sensory properties of fat in milk were examined by sensory descriptive analysis. To date, no single food additive has been completely successful in mimicking the sensory properties of fat in milk. This experiment investigated the effects of various factors and combinations thereof on sensory properties and perceived fattiness of milk, and compared them to the actual fat content (0.1; 1.3 and 3.5% fat milk was used). The other factors studied were the addition of thickener, whitener, cream aroma and homogenisation. Multivariate data analytical methods (Partial Least Squares Regression) were applied for analysis of the data. The three former additional factors contributed significantly to perceived fattiness of the milk, and homogenisation had a small but not significant effect. It was shown that a combination of thickener, whitener and cream aroma in 0.1% fat milk was approximately successful in mimicking sensory properties of 1.3% fat milk.

Food for patients at nutritional risk: a model of food sensory quality to promote intake.

BACKGROUND & AIMS The aim was to investigate food sensory quality as experienced and perceived by patients at nutritional risk within the context of establishing a framework to develop foods to develop foods to promote intake. METHODS Patients at nutritional risk (NRS-2002; food intake ≤ 75% of requirements) were observed at meals in hospital (food choice, hunger/fullness/appetite scores). This was followed by a semi-structured interview based on the observations and focusing on food sensory perception and eating ability as related to food quality. Two weeks post-discharge, a 3-day food record was taken and interviews were repeated by phone. Interviews were transcribed, coded, and analysed thematically. RESULTS Patients (N = 22) from departments of gastrointestinal surgery, oncology, infectious medicine, cardiology, and hepatology were interviewed at meals (N = 65) in hospital (82%) and post-discharge (18%). Food sensory perception and eating ability dictated specific food sensory needs (i.e., appearance, aroma, taste, texture, temperature, and variety defining food sensory quality to promote intake) within the context of motivation to eat including: pleasure, comfort, and survival. Patients exhibited large inter- and intra-individual variability in their food sensory needs. CONCLUSIONS The study generated a model for optimising food sensory quality and developing user-driven, innovative foods to promote intake in patients at nutritional risk.

Changing children's eating behaviour - A review of experimental research

The interest in childrens eating behaviours and how to change them has been growing in recent years. This review examines the following questions: What strategies have been used to change childrens eating behaviours? Have their effects been experimentally demonstrated? And, are the effects transient or enduring? Medline and Cab abstract (Ovid) and Web of Science (Thomson Reuters) were used to identify the experimental studies. A total of 120 experimental studies were identified and they are presented grouped within these 11 topics; parental control, reward, social facilitation, cooking programs, school gardens, sensory education, availability and accessibility, choice architecture and nudging, branding and food packaging, preparation and serving style, and offering a choice. In conclusion, controlling strategies for changing childrens eating behaviour in a positive direction appear to be counterproductive. Hands-on approaches such as gardening and cooking programs may encourage greater vegetable consumption and may have a larger effect compared to nutrition education. Providing children with free, accessible fruits and vegetables have been experimentally shown to positively affect long-term eating behaviour. The authors recommend future research to examine how taste and palatability can positively affect childrens attitudes and eating behaviour.

Effect of Time and Temperature on Sensory Properties in Low-Temperature Long-Time Sous-Vide Cooking of Beef

Slices of beef eye of round were sous-vide cooked for 3, 6, 9, and 12 hours at 56, 58, and 60°C. The results showed that descriptors from a sensory descriptive analysis were divided into two groups based on response to heat treatment. In one group (12 descriptors including juiciness), the intensity of the descriptors increased (or decreased) with both time and temperature. In the other (6 descriptors including tenderness), the intensity increased with temperature but decreased with time (or decreased with temperature but increased with time). The sensory properties of the cooked beef corresponding to the descriptors in the two groups can consequently not be optimized simultaneously, and a compromise between, for example, tenderness and juiciness, is necessary.

Sensory and instrumental characterization of low-fat and non-fat cream cheese

This study explored relationships between physical/chemical and sensory properties using a set of 20 low-fat and non-fat cream cheeses. High correlations were found between several descriptors; hand resistance (i.e., tactile firmness) was best predicted by squeezing flow viscometry (r = 0.90) and followed by dynamic oscillation (r = 0.86), steady shear viscometry (r = 0.83, excluding non-fat samples), and contraction flow viscometry (r = 0.80). However, taking into account the measurement uncertainty, similar maximal correlations were found for contraction flow and squeezing flow. Creaminess was found to be governed largely by oral graininess (r = −0.98), and was best predicted instrumentally by friction measurements (r = 0.90).

Selection of a subset of variables: minimisation of Procrustes loss between a subset and the full set

Abstract A statistical method to reduce a large set of variables to a smaller subset of variables was published by Krzanowski [Krzanowski, W. J. (1987). Selection of variables to preserve multivariate data structure, using principal components. Applied Statistics , 36 (1), 22–33]. An application in the field of sensory science is presented in this paper. The method selects the subset from all possible subsets by matching the multidimensional configuration of objects of the subset to the full set of variables. To this end a Procrustes rotation is used and the subset which produces the lowest Procrustes loss in this matching is selected as the optimal subset. For two data sets the loss values of all possible subsets of all possible sizes are studied. It is concluded that considering the subsets corresponding to a range of lowest loss values should be considered instead of only the subset producing the lowest loss value. The method can easily be extended to include fitting methods other than Procrustes rotations and other optimality criteria than the Procrustes loss employed here.

Culinary Science in Denmark: Molecular Gastronomy and Beyond

Noting that Denmark is traditionally an agricultural country and that a large part of the gross national product derives from the export of meat and processed food products, this article points out the paradox that only during the last decade has some Danish food-related research been genuinely driven by gastronomy and gastronomic innovation, and only recently have research activities and academic educational programs that include aspects of molecular gastronomy and other culinary sciences been initiated. At the same time, Denmark has placed itself on the international map due to innovative chefs winning top international awards and celebrated positions on lists of the best restaurants worldwide. Moreover, the New Nordic Cuisine movement has released novel driving forces and instigated new types of collaborations between chefs and scientists. Danish scientists of different orientations are being stimulated by the empirical world of gastronomy and cooking and are maturing molecular gastronomy as a science, and others have become proliferate writers and communicators of gastronomically inspired science; for example, within gastrophysics.

A review of instruments developed to measure food neophobia

BACKGROUND Food choices are influenced by an individuals attitude towards foods. Food neophobia may be associated with less variety of diets, inadequate nutrient intake and high product failure rate for new food products entering the market. To quantify the extent of these challenges, instruments to measure the food neophobia in different target groups are needed. Several such instruments with significantly different measurement outcomes and procedures have been developed. This review provides an overview and discusses strengths and weaknesses of these instruments. OBJECTIVE We evaluate strengths and weaknesses of previously developed instruments to measure neophobia and willingness to try unfamiliar foods. DESIGN Literature was searched through the databases Web of Science and Google Scholar. We identified 255 studies concerning neophobia and willingness to try unfamiliar foods. Of these, 13 studies encompassing 13 instruments to measure neophobia and willingness to try unfamiliar foods were included in the review. Results are summarized and evaluated with a narrative approach. RESULTS In the 13 instruments to assess neophobia and willingness to try unfamiliar foods, 113 to 16.644 subjects aged 2-65 years were involved, scales with 3-7 response categories were used and behavioral validation tests were included in 6 studies. CONCLUSIONS Several instruments to measure neophobia and willingness to try unfamiliar foods exist. We recommend selecting one or more among the 13 instruments reviewed in this paper to assess relevant aspects of neophobia.

Long-time low-temperature cooking of beef: three dominant time-temperature behaviours of sensory properties

BackgroundLong-time low-temperature sous-vide cooking of meat enables the chef to precisely and robustly reach a desired gastronomic outcome. In long-time low-temperature sous-vide cooking, time and temperature can be used as independent parameters to control the outcome. From a scientific point of view, this raises the question how different sensory properties of meat respond to time and temperature and the nature of the underlying processes.ResultsSensory properties of beef cooked at different combinations of low temperatures and long times were found to show three different time-temperature behaviours. By means of GEneralised Multiplicative ANalysis of VAriance (GEMANOVA), the behaviour of 18 descriptors could be reduced to three common time-temperature behaviours. This resulted in three groups of sensory descriptors: group A where temperature and time dependency strongly affect descriptors in the same direction, group B where temperature strongly and time less strongly affect descriptors in opposite directions, and group C where temperature and only to a small degree time affect descriptors in the same direction.ConclusionsThe underlying physical and chemical properties in these groups may be classified as depending on their response to time and temperature. Group A, consisting of mainly aroma and flavour descriptors but also juiciness, showed mainly kinetic nature; group B, consisting of texture descriptors (exemplified by tenderness), showed mostly kinetic nature as well; whereas group C, best exemplified by pink colour, showed little dependency on time and thus mostly reflected the effect of temperature. The results indicate that three different underlying main phenomena are responsible for the changes in the sensory properties during long-time low-temperature cooking of beef.