FOOD PRODUCTION: Where do we go from here?

FOOD: MORE THAN JUST A MEANS TO SURVIVE

Our eating habits have changed dramatically during the 20th century. In the first 50 years, especially in the immediate aftermath of World War II, food was simply a source of energy. Today it is also a sensory, cultural and social phenomenon. As well as providing enjoyment, we now want food to enhance our health and well being. Furthermore, many of us are no longer willing to spend scarce leisure time preparing elaborate meals. Our food has to be quick and convenient to prepare, as well as healthy and tasty. Finally, we expect our food to be reasonably priced. In short, our food has to be tasty, safe, cheap, healthy, available all year round, "as natural as possible", varied, and sometimes elegant or exotic.

We may take all this for granted, but catering to a market of more than 350 million people in central Europe alone is no easy task. Moreover, as the population grows, the number of agricultural growers is declining. This increases the pressure on transport and storage systems, especially since many raw materials are not grown in Europe. It may seem impossible to meet all the demands. However, technological progress in food manufacturing and recent discoveries in nutritional science have resulted in increasingly high food quality standards and enormous food variety.

AN OLD SAYING BUT A TRUE ONE: YOU ARE WHAT YOU EAT

Our lifestyle and eating habits underwent radical change only "at the very last minute" on the evolutionary calendar. As late as the 15th century, cabbage, milk, barley, watery soup with lard, and a little meat every now and then was the standard European diet. Until a few decades ago, strenuous manual labour involving high energy consumption was normal. These days, we tend to have sedentary occupations.

Many of us could improve the imbalance between calorie intake and physical activity. However, in recent years there is evidence that recent discoveries about diet are starting to have an impact on our eating habits. We are now more inclined to choose lean meat, vegetables, and foodstuffs high in dietary fibres.

HEALTHY, HEALTHIER, HEALTHIEST... DIETS IN THE 21ST CENTURY

As modern nutritional sciences provide more information about the mechanisms by which certain food ingredients influence our body functions, scientists and market experts agree that foods with a declared positive impact on health are growing in popularity. Market analyses of consumer demands and behaviours forecast that within the next few years, nearly every product group will include special health-enhancing foods (1). Science focuses on reducing risk for chronic illnesses and debilitating diseases, particularly on cardiovascular diseases, obesity, cancer, osteoporosis and non-insulin dependent diabetes.

Lifestyle	Fat	Sugar	Starch	Protein	Fibre (g/day)
Hunter-gatherers	15-20	0	50-70	15-20	40
Peasant-farmers	10-15	5	60-75	10-15	90
Affluent societies	40+	20	25-30	12	20

SURVIVAL STRATEGIES FOR BENEFICIAL MICRO-ORGANISMS

Up until a few years ago, few of us knew the meaning of the words probiotic and prebiotic. Now foods based on these principles appear in all supermarkets. The success of prebiotic substances is due to the positive effects of special components of dietary fibres on the microbial flora of the digestive tract and that of probiotics to selected lactic acid-bacteria strains that appear to have a positive effect on bowel function. Many research groups are investigating the potential role of pro- and prebiotics in colon cancer prevention. Our gastric and intestinal milieu is intentionally designed by nature to ward off and kill micro-organisms ingested with food. However, at least some of these probiotic lactic acid bacteria seem to survive the passage through the stomach and small intestine and take up residence in the large intestine to exert their beneficial effects, if ingested regularly.

STATE-OF-THE-ARTS FATS

Progress has been made in the area of fats. A diet low in saturated fats and at the same time high in unsaturated fatty acids is good for everybody, not just people with heart disease. Unsaturated fatty acids help reduce the bad cholesterol levels, thereby reducing the risk of heart disease (2). Bread and eggs containing increased amounts of one of these essential fatty acids (omega-3) are already available on the market. Flax and fish are naturally rich in omega-3 fatty acids. Thus, some hens are fed flax to influence the fatty acid composition of the eggs they lay.

Plants with a fat composition beneficial to the diet are already being bred, e.g. certain canola or soybean varieties. Biotechnological approaches to plant breeding are promising here, because they offer the opportunity to design different qualities of oil . The nutritive fatty acid content of oil plants, especially canola, soybean, sunflower and maize, can be enhanced and the fatty acid composition selectively modified. One canola variety under development has a high stearate content, making hardening of the fat superfluous. This may help minimise levels of undesirable trans fatty acids in our dietary fat. Research on using special enzymes to create dietary fat molecules containing high concentrations of essential fatty acids is being pursued. However, the health-enhancing effects of polyunsaturated fatty acids require the support of specific protective agents, so-called antioxidants, which represent just one group of the ever growing collection of phytochemicals - plant compounds that are attracting increasing attention in dietary medicine.

THE POWER OF PHYTOCHEMICALS

All plants contain numerous phytochemical compounds, usually in minute concentrations. These phytochemicals may exert highly specific effects in the organism. They may reduce the risk of a wide range of ailments, such as abnormal heart rhythm, coronary heart disease, stroke, hypertension, osteoporosis, certain cancers or gastrointestinal disorders. They might keep the arterial linings smooth and increase enzyme activities to detoxify carcinogens. Plant-derived medicines have long taken advantage of the effects of such active plant ingredients and modern molecular biology and medicine play key roles in understanding the underlying mechanisms of action in the human body. The plant stanol esters in soybeans, wheat and rice may reduce high cholesterol levels by mimicking cholesterol in the gut and thus reducing its uptake (3). Besides plant breeding efforts to increase the content of desired phytochemicals in crops, their isolation and the fortification of special foods with these compounds is already in progress and the first of such products have entered the marketplace.

Food/ingredient	Modification	Status	Food effect
Canola, soybean, sunflower oil	Fatty acid composition: - High oleic, high laurate - High stearate	On the market/under development	- Increase of unsaturated and reduction of saturated fatty acids - No fat hardening, no formation of trans fatty acids
Cholesterol-free fish oil	Removal of cholesterol with cyclodextrins	On the market	Lowering of blood cholesterol level, prevention of atherosclerosis
Omega-3 bread	Bread mixtures fortified with essential fatty acids	On the market	Contributes to reducing the risk of heart disease, provides essential fatty acids
Synthetic fats	Enzymatic modification and synthesis of fat molecules	On the market	Special flavours by short chain fatty acids, healthy fat molecules with high content in essential fatty acids

ANTIOXIDANTS ARE EN VOGUE

Certain substances play an important role in preventing oxidative damage in connection with cardiovascular diseases. Vitamins, C, E and carotenoids may be the most important antioxidants and boosters for our immune system. Besides vitamins and carotenoids, recent studies on several other phytochemicals, e.g. phenolic compounds, indicate that they have a beneficial effect on chronic disorders such as cardiovascular disease (see table 3). They contribute to reducing the level of LDL cholesterol damaged by oxidation in the blood, thus preventing plaque deposits in the blood vessels.

The role of antioxidants in cancer prevention is also being investigated. Cancer is caused by damaged genes in the body cells. Affected cells lose their ability to react normally; they proliferate to the detriment of their environment. Antioxidants trap and neutralise certain substances that can damage the genetic material by oxidation. For example, lycopene in tomatoes is a carotenoid that may help protect against prostate cancer. Glucosinolates, which are mainly found in cabbage, are now known to have anti-carcinogenic properties. Sinigrin and its metabolites belong to this group. Research suggests that tumour cells are driven to 'commit suicide' through the impact of sinigrin on the immune system (4). Attempts are under way to breed broccoli varieties with a high glucosinolate content.

CONVINCING DATA ON PHYTOESTROGENS

Phytoestrogens, i.e. plant-based substances that express hormone-like features in the body, belong to another group of phytochemicals. Beans and lentils can contain high levels of phytoestrogens. The relatively high level of consumption of soy products in Asia is thought to be one reason for the comparatively low occurrence of breast cancer in these countries. The role of phytoestrogens in preventing certain types of breast cancer is being investigated. Phytoestrogens such as isoflavones are among the most valuable phytochemicals. They seem to lower the risk of heart diseases by inhibiting blood clot formation. Studies show that they help prevent or alleviate osteoporosis and menopausal symptoms by filling in for estrogen, when production declines in menopausal women.

Plant substance	Class	Compound	Possible effects
Yellow, orange and red fruits and vegetables, vegetable greens	Carotenoids	Beta-carotene, lycopene, xanthophylls	Antioxidative, anticancer, immune modulatory
Different plant seeds, plant oils	Phytosterines	Beta-sitosterin, stanol esters	Lowering cholesterol uptake
Mustard, kohlrabi, broccoli, horse-radish	Glucosinolates and their metabolites	Indole, isothiocyanates, sinigrin	Antimicrobial, anticancer
Outer layers of fruits (e.g. grapes), vegetables and grains	Polyphenols	Phenolic acids, flavononids	Anticancer, antimicrobial, antioxidative
Pulses, grains	Proteins	Protease inhibitors	Antioxidative, anticancer, lowering blood glucose level
Peppermint, citrus fruits	Monoterpenes, limonoids	Menthol, limonene	Anticancer
Pulses, whole grains, linseed	Phytoestrogens	Lignans, isoflavones (e.g. genestein, dadazein)	Anticancer, antioxidative (via acting as estrogens or anti-estrogens)
Onion, garlic	Sulfides and metabolites	Alliin and metabolites	Anticancer, antimicrobial, lowering blood pressure
Cranberries	Unknown	Unknown	Prevention of bacterial infections of the urinary tract
Oat, barley	Soluble fibre	Beta-glucan	Cholesterol-lowering

MEETING SPECIFIC DIETARY NEEDS

Numerous plant ingredients have already been shown to be beneficial in disease prevention. With our increasing knowledge on the importance of various nutrients, diets can be developed to meet specific needs.

The range of foodstuffs customised to suit the nutritional requirements of groups such as the elderly, pregnant or breast-feeling women, infants, young children and athletes is growing all the time. Such foods are characterised by a balanced composition of energy suppliers in the form of fats, carbohydrates and proteins, and by a cocktail of vitamins and minerals composed according to the current state of scientific knowledge. For many elderly, there is the advantage that the same foods may provide a balanced diet and a sufficient supply of vitamins, essential amino acids and minerals without changing long standing habits.

Attempts to identify new compounds with health-enhancing properties are continuing and will lead to healthier diets in the future. At the same time, there are many unanswered questions to food functionality. For example, little is known about the action of different phytochemicals within the body: bioavailabilty (to what extent substances reach the site of action in the body and deliver their beneficial effects), metabolism and possible dose-related adverse effects are important questions needing further study. Furthermore, some effects might be due to synergy, and might not be caused by a single component. The ongoing elucidation of the role of these phytonutrients will confirm today's recommendations for a healthy lifestyle, including a varied diet, a balanced energy intake and daily exercise as the most important factors.

Crop	Compound to be removed	Compound's effects	Removal via
Manioc	Cyanide	Highly toxic	Heating, Genetic engineering
Nuts, pulses, certain vegetables	Allergenic protein	Food allergies	Not possible today, only protein hydrolysis or lowering of content by conventional breeding and genetic engineering. Future: genetic engineering?
Potato	Chaconine, solanine	Highly toxic	Cooking, Conventional breeding
Pulses	Lectins	Toxic	Cooking (destruction), Genetic engineering (prevention of formation)
Wheat, rye, oat	Gluten	Coeliac disease	Not possible today, only lowering of content by conventional breeding. Future: genetic engineering?

NATURE DOES NOT EXCLUSIVELY "DO GOOD"

Modern plant breeding techniques are used to develop new varieties with reduced levels of undesirable compounds. Some foods can cause problems for people with food allergies. However, allergen free plants can be bred only if the allergy-inducing proteins (allergens) have been identified. Genetic engineering is used to produce allergens in amounts sufficient for scientific analysis, and modern molecular biology and medicine have taught us much about their properties. For example, we know that they can survive for a long time in the hostile environment of the digestive tract. There are still technological constraints to allergen removal, but this might be one of the most promising developments in plant biotechnology: Scientists have bred varieties of rice that are low in allergenic proteins. The goal is to produce varieties that contain none of the predominant rice allergens and thus accommodate even hypersensitive consumers. Suitably adapted wheat, rye or barley varieties would also benefit people suffering from coeliac disease.

SPARING AND SAFE

In addition to plant breeding efforts to remove or introduce specific traits into food, other new techniques and improved processing methods ensure that valuable nutrients are preserved. The immense technological progress in food manufacturing is particularly evident in the area of quality standards and safety.

Today, many food companies operate world-wide, from the sourcing of raw materials or ingredients to marketing. Safety requirements are of global significance along the whole food production chain. From harvest of the raw materials to storage of processed food products in the home, a key concern is suppressing the growth of unwanted organisms that may spoil food. Meeting safety standards while maintaining organoleptic quality is a challenge that can be met only with sophisticated technological efforts.

EXAMINING ALL THE FACETS

Unwanted micro-organisms such as Listeria, Salmonella, Clostridium or Escherichia coli need moisture, neutral pH values, low salt and sugar concentration and moderate temperatures to grow. Approaches have been undertaken to prevent the growth of these micro-organisms even after mild processing conditions, for example, various combinations of heat and acid treatments, addition of antimicrobials, magnetic field pulses or computer aided design of equipment that is easily cleaned (5). As heating can destroy sensitive food ingredients, e.g. vitamins, modern pulse heat treatment involves very brief heating interspersed with cooling phases. Another way to combat microbial growth is water extraction, i.c. industrial microwave drying of fruits or spray-drying of milk. Microwave drying offers the avantage of relatively low temperarures combined with the reduction of pre-existing moisture levels resulting in preserving valuable nutrients and flavours.

Air filtration, aseptic packaging and protective atmospheres are used to reduce food spoilage, but freezing still plays a key role. Therefore, current research efforts concentrate on changes of nutrients and texture in foods during cold storage to further optimise freezing processes and product composition. Another recent development is the application of high pressure pasteurisation in fruit and vegetable products. This procedure will increase the shelf life of products while preserving the nutritional content, flavour and colours. UV irradiation of process water is an increasingly used method of disinfection. A recent development is the use of circular sugar molecules of various sizes with wide application range (cyclodextrins), e.g. to trap and remove certain micro-organisms such as Listeria species from foodstuffs. Until we pick up our food from the market's shelves, modern sensitive detection methods accompany the production process to ensure high quality food.

Technology	Used for	Mode of action
Electronic beams	Food safety	Pasteurisation
Pulsed voltage	Food safety	Killing of micro-organisms, conservation of vitamins, etc.
Polymerase Chain Reaction (PCR)	Quality, food safety	Identification of food origin/composition, detection and identification of pathogens
Food irradiation (upcoming)	Food safety	Killing harmful micro-organisms in spices, poultry, meat
Breeding (conventional and genetic engineering)	Food safety, quality	Modification or transfer of (distinct) genes being responsible for defined new characteristics
Sonification	Preparation of emulsions	Extremely fine mixing of water-oil mixes leading to a creamy product
Magnetic resonance images	Food safety	Production of temperature images of foods to supervise freezing, drying or heating processes
Molecular imprinting of polymers	Food quality, food safety	Capture of undesired molecules/bacteria; slow release of flavour compounds, isolation of desired molecules from raw material
Robots	Food safety	Sterile food processing, storage, packaging
Enzymatic catalyses	Food safety	Flavour and ingredient production. Destruction of bacteria, cleavage or metabolisation of certain compounds into desired substances (e.g. butter or cheese flavour, aromatic proteins)

MODERN FOOD DIAGNOSTICS

Experts can determine the condition of food by measuring temperature, acid content, the presence of certain metabolic products, or the quantity or type of micro-organisms in a sample of safety controls. Besides conventional practices such as physiochemical characterisations, state-of-the-art molecular genetic methods are also widely used to identify spoilage bacteria. These techniques are also applied to check whether any of the rare but harmful strains of E. coli bacteria are present. These methods can also help to determine the origin of unwanted germs - have they come from an employee's hands or are they from an ingredient that was already contaminated at the time of purchase? It is also possible to quickly analyse foodstuffs, for example for fat or flavour content, by chromatographic and/or spectrometric methods. These techniques make it possible to answer certain questions (e.g. whether there are grapefruit solids present in orange juice), by analysing specific polyphenolic compound compositions in these fruits. The content of naturally occurring substances injurious to our health (e.g. certain fungal metabolites such as mycotoxins) can also be determined by these techniques or by sensitive immunochemical methods. This enables food producers to ensure that only high-quality materials end up in final food products.

New tests based on molecular genetics can also be used to investigate a food's origin. "Was it really wild boar or just plain pork?" "Is this steak really from Argentina?" "Was it a buck or a doe?" Questions like these are easier to answer nowadays. And in the case of genetically modified foods, the newly inserted genetic material can be detected easily by molecular genetics (6).

IMPROVING HELPFUL MICRO-ORGANISMS

Many micro-organisms, including various types of lactic acid bacteria, some fungi and yeasts, have been used in food processing for thousands of years. Examples are the production of drinks (e.g. beer, cocoa, coffee, tea, wine), sour cream, yoghurt and cheese, bread and bakery goods, sausages and sauerkraut. The micro-organisms contribute both to flavour and the preservation of foodstuffs, as they take part in suppressing the growth of unwanted germs (7). However, some of these beneficial bacteria are susceptible to viral infection and bacterial viruses can cause substantial production losses. Therefore, scientists are working on breeding new virus-protected cultures. Others are developing substances called bactericines that can specifically inhibit the growth of undesirable micro-organisms. These genetically modified microorganisms will play a role in enhancing the safety and quality of our foods, and will contribute to further improvement of economical and ecological aspects of food production (8).

Most of us take food safety for granted, and pay far more attention to organoleptic and convenience aspects of our food. However, the underlying technological demands are high on both aspects. Food processing methods are being improved continuously to cater to a growing market for convenience foods and pleasurable eating. Manufacturers' research follows the consumer trend, as efforts are taken to investigate the impact of food preparation techniques on sensory quality. The particle size of powdered ingredients determines whether we perceive a "gritty" or "creamy" texture. This is important in the case of carbohydrate-based fat substitutes, for example. Spray drying or special precision dryers are used to fine-tune particle size to within a few fractions of a millimetre. Sound plays a role in the pleasure obtained from eating potato crisps. The crisps have to be big enough so that they do not fit into our mouths all at once. Otherwise we will not hear the crunch that is an essential part of the eating experience.

Micro-organism	Product/characteristics	Purpose
Dairy starter cultures	Virus resistance	Reduction of production losses due to virus infection
	Production of bactericines	Growth inhibition of undesired micro-organisms, reduction of production steps and costs
	Synthesis of flavour compounds	Better taste, less production steps
	Synthesis of vitamins	Nutritional value of products
Starter cultures for meat processing	Production of bactericines	Growth inhibition of undesired micro-organisms
Baking yeast	Expression of a time additional enzyme	Reduction of dough raising
Brewing yeast	Expression of additional enzymes	Calorie reduction, simplification of filtering process

IMPROVING TASTE

Modern breeding methods and plant biotechnology can be used to breed tastier fruits and vegetables. The taste of peas, tomatoes and many other fruits or vegetables improves with increasing sugar content. Varieties of strawberry, raspberry, pineapple or banana that ripen slowly and stay firm are also under development. With meat products, food scientists are investigating the causes of the loss of taste and texture associated with the desired low fat content so they can produce low-calorie foods with sensory appeal.

Organoleptic aspect	Food/food ingredient	Aim/technology	Products
Sweetness, flavour	Fruits (e.g. strawberry, pineapple), vegetables (e.g. pea, tomato)	Increase of sugar content by genetic engineering	Not commercialised
	Dairy products, beverages, sweets	Development of new flavours	Energy drinks, yoghurt
	Various products	Slow release of flavour molecules from cyclodextrines	Not commercialised
Creaminess (mouth feel)	Fat replacers	Spray drying, grinding	Calorie-reduced ice-cream, dessert
Crunchiness	Snacks, biscuits	Different product composition (increased fibre content), product shape/size	Many commercialised (potato crisps, cookies, breakfast cereals)
"Fancy" colour	Beverages, sweets	Product composition (food dyes)	Many commercialised (beverages, sweets, ice-cream, icings)

QUICK AND EASY

Consumers expect convenience food to be quick and easy to prepare and to meet high nutritional standards. Although there are some niches left where it is not possible to buy ready-to-consume meals, the increasing range of convenience foods for preparation at home reflects the changing social and cultural structures in many industrial countries. More people live alone, and more women work outside the home. On going technological developments make their contribution to our changing demands.

MEETING TOMORROW'S DEMANDS

Meeting consumer demands in this new century is a big challenge in terms of safety, health, organoleptic, economic and sustainable aspects and will require further scientific and technological progress. Our awareness of the importance of a healthy diet and an active lifestyle parallels our growing scientific knowledge on the beneficial effects of various ingredients. The number of foods with scientifically proven health benefits will increase within the next decades, but they will not be a panacea for poor dietary habits. As the matter gets more and more complex, it will be very important to keep informed. Only then will our future food contribute to a healthy lifestyle.

Reviewed by Prof. Dr. Klaus-Dieter Jany
Federal Research Institute for Nutrition, Karlsruhe, Germany

REFERENCES

• Functional/Designer Foods And Beverages: Trends and Developments for Marketers Chapter 3.3.1: Current and Potential Functional Products Source Business Communication Company, Oct. 1997.
• Food choice, Diet and Health: Diet and tissue integrity. Institute of Food Research, Annual Report 1997.
• Jones PJ, MacDougall DE, Ntanios F, and Vanstone CA (1997): Dietary phytosterols as cholesterol-lowering agents in humans. Canadian Journal of Physiology and Pharmacology 75(3), 217-227.
• Smith TK, Lund EK, and Johnson IT (1998): Inhibition of dimethylhydrazine-induced aberrant crypt foci and induction of apoptosis in rat colon following oral administration of the glucosinolate sinigrin. Carcinogenesis 19(2), 267-73.
• Gould GW (1998): New approaches to the microbial stability and safety of foods. 3rd Karlsruhe Nutrition Symposium 1998, Proceedings Part I, 12-19.
• Greiner R, and Konietzny U (1997): Is there a possibility to identify processed foods as produced through genetic engineering by PCR technology? In: Schreiber GA, and Bögl KW (Eds.): Foods Produced by Means of Genetic Engineering. 2nd Status Report, 100-102. Bundesinstitut für gesundheitlichen Verbraucherschutz und Veterinärmedizin (BgVV) Berlin, Germany ISBN: 3-931675-07-6.
• The basics of making cheese. In: http://www.ebs.hw.ac.uk/SDA/book1.html#rennet, website of The Scottish Dairy Association.
• Heller KJ (1997): Potential of the application of genetically engineered microorganisms in food production: An overview. In: Schreiber GA, and Bögl KW (Eds.): Foods Produced by Means of Genetic Engineering. 2nd Status Report, 14-21. Bundesinstitut für gesundheitlichen Verbraucherschutz und Veterinärmedizin (BgVV) Berlin, Germany ISBN: 3-931675-07-6.

REVISTA EUFIC 05/2000