Rowett food reports - The University of Aberdeen · Rowett food reports ... choice) and disadvantages (eg toxic compounds, nutrient losses) of processed foods. ... (hurdle technology)

Rowett food reports

Nutritional Implications of Industrial Food Processing

I N S I G H T S

I N T O

S C I E N C E

The Rowett Institute of Nutrition and Health

We undertake research to address contemporary problems in nutrition, which makes a significant contribution to increased scientific knowledge, underpins Government policies and informs innovation for industry.

Garry Duthie is Professor of Nutritional Science at the University of Aberdeen. He is Head of Human Studies at the Rowett Institute of Nutrition and Health, University of Aberdeen and is also leader of the Natural Products Research Group. His research focuses on the mechanisms by which dietary factors prevent or promote the development of diseases such as heart disease and cancer.

C O N TA C T

PROF. GARRY DUTHIE

Email [email protected]

Professor Garry Duthie

Consumption of ketchup leads to a greater and more prolonged increase in plasma lycopene concentrations than is observed when consuming tomatoes with a similar lycopene content (Fig 3). The release of lycopene from the plant cells during ketchup manufacture improves availability and subsequent absorbtion.8 Vitamin C is required to prevent scurvy and may play a role in preventing cardiovascular disease. Consequently fortification of processed foods with specific micronurients to compensate for such losses may be required.

ConclusionsOur consumption of industrially processed food is a recent event in relation to our evolutionary history and the consequence for our health is a matter of contentious debate. However, food processing is a fact of modern life and its continual innovations may be the only means of sustaining an ever expanding population on our planet. There are advantages (eg. improved availability, choice) and disadvantages (eg toxic compounds, nutrient losses) of processed foods. The nutritional consequences of consuming processed foods is arguably under-researched. There needs to be continual open dialogue between academic scientists and the food industry to develop processing procedures which maximise the health properties of processed foods while still being profitable and attractive to the consumer. Please do not hesitate to contact us for further information.

References1. Southgate DAT. Food processing. In Human Nutrition and Dietetics (eds Garrow JS, James WPT, Ralph A) 2000, 397-409. Churchill Livingstone.

2. Knorr D, Froehling A, Jaeger H, et al. Annu. Rev. Food Sci. Technol. 2011, 2, 203-205.

3. Somza V. Mol. Nutr. Food Res. 2009, 53, 1485-1486.

4. Hooper L, Barlet C, Davey SG, Ebrahim S. Cochrane Datbase Syst Rev 2004, 1: CD003656

5. Lichtenstein AH, Kennedy E, Barrier P et al. Nutr. Rev. 1998, 56, S3-19.

6. Eaton SB, Konner M. New Eng. J. Med 1985, 283-289.

7. Stender S, Dyerberg J, Bysted A. et al. Atherosclerosis Supplements 2006, 7, 46-52.

8. Shi J, Le Maguer M. Crtical Rev. Food Sci. Nutr. 2000, 40, 1-42

Rowett Institute of Nutrition and Healthwww.abdn.ac.uk/rowettTel: +44(0)1224 712751Fax: +44(0)1224 715349


ISSUE 03 SPRING 2012Repor t author:


BackgroundFood processing converts primary animal and plant products into edible foods. The majority of food we consume in the UK has been industrially processed in some way. Processing techniques increase the stability of the product and permit the consumer to choose from a wide range of food items all year round. Some argue that without food processing methods it would be difficult for industrialised countries to sustain their populations.1 The main pressure on food processors is to return a profit. Unsurprisingly, there is a tendency to focus on producing foods which appeal to the customer in terms of taste, visual appeal and price. Such foods may be sub-optimum from a nutritional standpoint and may not be compatible with current health messages. This brief report summarises current industrial food processing procedures and discusses the consequences for the nutritional value of food.

Methods of food processingTraditional methods of food processing such as sun drying, oven drying, smoking, salting, pickling and fermenting require little equipment. Such procedures reduce microbiological activity and in the pre-industrial era allowed foods to be stored against times of scarcity. Early technological innovations to preserve food were canning (early 1800s), pasteurisation (1860s), freeze drying (early 1900s) and deep freezing (1920). These methods are still in use today. However, there are now a whole range of newer technologies employed by the food industry to provide palatable, safe food. These include

• the use of modified atmospheres• the addition of preservatives (eg sulphites, benzoates, nitrites)• the control of microstructure (eg emulsions, matrices, extrusions)• manothermosonication (combined ultrasonics, heat and pressure)• irradiation• the use of high magnetic field pulses• electroporation (high voltage electric gradient pulses)

Figure 3: Schematic of how processing of tomatoes to form ketchup improves uptake of lycopene, a plant carotenoid.

Such processes can have both beneficial and undesirable consequences. For example, use of electric fields and high pressures may limit formation of undesirable compounds and retain freshness to the food product. On the other, microbiological spores may not be destroyed and flavour characteristics may be negatively altered. Nowadays, several processing approaches may be combined (hurdle technology) to increase shelf life and ensure the food item is safe for consumption.2

“The foremost beneficial

effect of food processing is

the reduction or removal of

unwanted micro-organisms.”

Supported by Scottish Government “Enhancing health benefits from food through production and processing” programme

Beneficial aspects of food processingThe foremost beneficial effect of food processing is the reduction or removal of unwanted micro-organisms. However, there are several other economic and societal benefits which appeal to manufacturers and consumers (Table 1).

Beneficial aspects Action ConsequenceFood safety Inactivation of pathogens and natural

toxins and prevention of formation of oxidised compounds.

Improved product shelf-life.

Sensory quality Formation or inclusion of compounds which enhance texture, flavour and taste.

Improve consumer acceptability and demand.

Diversity Independence from seasonal availability and access to wide range of products.

Widening of consumer choice.

Cost Bulk buying of primary products and ingredients.

Economy of scale leading to lower cost to consumer.

Convenience Increase supply of ready-to-eat and semi-prepared foods.

Less preparation time for consumer.

Potentially undesirable effects of food processingFood processing can lead to undesirable reactions and the formation of compounds which are potentially toxic (Table 2). Many are formed during Maillard reactions which are a complex series of chemical interactions that occur when proteins are heated in the presence of carbohydrates. Laboratory studies potentially implicate compounds arising from food processing methods in the development of several clinical conditions such as cancer and heart disease although this does not necessarily mean that they produce a health risk to humans in the quantities found in certain processed foods.3

Nevertheless, regulatory authorities impose stringent limitations on the amount permissible in foods.

Compounds Description Possible adverse effects3-chloro-propane-1,2-diol (3MCPD) By-product of the manufacture of

hydrolysed vegetable protein. Also found in soya products and a range of cereal products.

Carcinogenic, antifertility agent

Trans fatty acids Formed during the partial hydrogenation of vegetable oils to a semi-solid state for use in manufacturing processes.

Promote coronary heart disease

Acrylamide Formed from the condensation of the amino acid asparagine with reducing sugars such as fructose or glucose upon heating.

Carcinogenic

Heterocyclic amines Formed from free amino acids, creatine, and glucose under variety of conditions including processing time and temperature.

Carcinogenic, neurological disorders

Polycyclic aromatic hydrocarbons Produced by pyrolysis of fats and wood smoke curing and preservation.

Carcinogenic, mutagenic,

Acrolein Formed during different stages of processing from frying of vegetable and animal fats.

Carcinogenic

In addition to the formation of undesirable compounds, processed foods can have high levels of salt and fat. A high salt intake raises blood pressure and increases risk of stroke and cardiovascular events. Historically, salt was used as a preservative but it is now also widely used by the food industry to enhance the palatability of processed foods. Only 5% of salt consumed is naturally present in foods and 15% is added at the table or in domestic cooking. The remainder (80%) is added by the food industry.4 Similarly, the fat content of processed foods can exceed dietary recommendations as it favourably enhances taste and hence consumer preference. Excessive intake of fat is associated with cardiovascular disease, diabetes and obesity.5

Table 2: Some potentially harmful compounds arising from food processing procedures

Table 1: Beneficial aspects of food processing

Such processes can have both beneficial and undesirable consequences. For example, use of electric fields and high pressures may limit formation of undesirable compounds and retain freshness to the food product. On the other, microbiological spores may not be destroyed and flavour characteristics may be negatively altered. Nowadays, several processing approaches may be combined (hurdle technology) to increase shelf life and ensure the food item is safe for consumption.2

“The foremost beneficial

effect of food processing is

the reduction or removal of

unwanted micro-organisms.”


Beneficial aspects of food processingThe foremost beneficial effect of food processing is the reduction or removal of unwanted micro-organisms. However, there are several other economic and societal benefits which appeal to manufacturers and consumers (Table 1).

Beneficial aspects Action ConsequenceFood safety Inactivation of pathogens and natural

toxins and prevention of formation of oxidised compounds.

Improved product shelf-life.

Sensory quality Formation or inclusion of compounds which enhance texture, flavour and taste.

Improve consumer acceptability and demand.

Diversity Independence from seasonal availability and access to wide range of products.

Widening of consumer choice.

Cost Bulk buying of primary products and ingredients.

Economy of scale leading to lower cost to consumer.

Convenience Increase supply of ready-to-eat and semi-prepared foods.

Less preparation time for consumer.

Potentially undesirable effects of food processingFood processing can lead to undesirable reactions and the formation of compounds which are potentially toxic (Table 2). Many are formed during Maillard reactions which are a complex series of chemical interactions that occur when proteins are heated in the presence of carbohydrates. Laboratory studies potentially implicate compounds arising from food processing methods in the development of several clinical conditions such as cancer and heart disease although this does not necessarily mean that they produce a health risk to humans in the quantities found in certain processed foods.3

Nevertheless, regulatory authorities impose stringent limitations on the amount permissible in foods.

Compounds Description Possible adverse effects3-chloro-propane-1,2-diol (3MCPD) By-product of the manufacture of

hydrolysed vegetable protein. Also found in soya products and a range of cereal products.

Carcinogenic, antifertility agent

Trans fatty acids Formed during the partial hydrogenation of vegetable oils to a semi-solid state for use in manufacturing processes.

Promote coronary heart disease

Acrylamide Formed from the condensation of the amino acid asparagine with reducing sugars such as fructose or glucose upon heating.

Carcinogenic

Heterocyclic amines Formed from free amino acids, creatine, and glucose under variety of conditions including processing time and temperature.

Carcinogenic, neurological disorders

Polycyclic aromatic hydrocarbons Produced by pyrolysis of fats and wood smoke curing and preservation.

Carcinogenic, mutagenic,

Acrolein Formed during different stages of processing from frying of vegetable and animal fats.

Carcinogenic

In addition to the formation of undesirable compounds, processed foods can have high levels of salt and fat. A high salt intake raises blood pressure and increases risk of stroke and cardiovascular events. Historically, salt was used as a preservative but it is now also widely used by the food industry to enhance the palatability of processed foods. Only 5% of salt consumed is naturally present in foods and 15% is added at the table or in domestic cooking. The remainder (80%) is added by the food industry.4 Similarly, the fat content of processed foods can exceed dietary recommendations as it favourably enhances taste and hence consumer preference. Excessive intake of fat is associated with cardiovascular disease, diabetes and obesity.5

Table 2: Some potentially harmful compounds arising from food processing procedures

Table 1: Beneficial aspects of food processing

“Consumption of processed

foods is a very recent event in

our evolutionary lifespan”

Nutritional consequences of food processingModern human beings appeared about 40,000 years ago and our genetic constitution and nutritional requirements have changed relatively little since then. The diverse range of macronutrients and micronutrients we require to maintain health was originally obtained from primary animal and plant products. Consumption of processed foods is a very recent event in our evolutionary lifespan. Consequently we may be poorly adapted in relation to the chemical and physical changes to nutrients during some food processing procedures.6 For example, native proteins may be denatured or form aggregates and starches may undergo crystallisation (Fig.1). This may alter digestibility compared with consuming the nutrients in a non-processed primary product.

Changes in the structure of fats during processing also can be problematical. For example, trans fatty acids (Fig 2) formed during the partial hydrogenation of vegetable oils to a semi-solid state for use in manufacturing processes have been associated with heart disease, Alzheimer’s, diabetes and cancer. Their use is banned in Denmark, and there is pressure on the UK food industry to minimise the use of trans fats the food chain.7

Nutrient Causative processesVitamin C Water leaching,heat,oxygenBiotin Alkaline conditionsCarotenoids Heat,lightVitamin B12 Alkaline,acid conditionsFolic acid Heat,lightNiacin Water leachingPantothenic acid Heat,alkaline,acidRiboflavin Heat,light,alkaliThiamine Water leaching,oxygen,heat,

light,alkaline conditionsVitamin K Light,alkaline conditionsVitamin A Heat,light,oxygenVitamin D Light,oxygen, alkaline conditions

Adequate intakes of vitamins are essential to maintain health. Many of these micronutrients are sensitive to heat, oxygen and pH (Table 3). Generally processing can lead to a decrease in the amount of these micronutrients in foods.

Figure 1: Schematic of changes in structures of starch and proteins that can arise from food processing

For example, canning can decrease vitamin C content by 70% compared with the amount in the original ingredients. Vitamin C is required to prevent scurvy and may play a role in preventing cardiovascular disease. Consequently fortification of processed foods with specific micronurients to compensate for such losses may be required.

In contrast, processing can release nutrients and bioactive compounds from the food matrix where they are bound. As a result digestibility and bioavailability may be improved compared with that achieved when consuming the non-processed primary products. A classical example is lycopene, a carotenoid found in tomatoes which may have health benefits.

Figure 2: Structures of a “normal” and trans fatty acid produced during processing.


Table 3: Effects of processing procedures on some vitamins

“Consumption of processed

foods is a very recent event in

our evolutionary lifespan”

Nutritional consequences of food processingModern human beings appeared about 40,000 years ago and our genetic constitution and nutritional requirements have changed relatively little since then. The diverse range of macronutrients and micronutrients we require to maintain health was originally obtained from primary animal and plant products. Consumption of processed foods is a very recent event in our evolutionary lifespan. Consequently we may be poorly adapted in relation to the chemical and physical changes to nutrients during some food processing procedures.6 For example, native proteins may be denatured or form aggregates and starches may undergo crystallisation (Fig.1). This may alter digestibility compared with consuming the nutrients in a non-processed primary product.

Changes in the structure of fats during processing also can be problematical. For example, trans fatty acids (Fig 2) formed during the partial hydrogenation of vegetable oils to a semi-solid state for use in manufacturing processes have been associated with heart disease, Alzheimer’s, diabetes and cancer. Their use is banned in Denmark, and there is pressure on the UK food industry to minimise the use of trans fats the food chain.7

Nutrient Causative processesVitamin C Water leaching,heat,oxygenBiotin Alkaline conditionsCarotenoids Heat,lightVitamin B12 Alkaline,acid conditionsFolic acid Heat,lightNiacin Water leachingPantothenic acid Heat,alkaline,acidRiboflavin Heat,light,alkaliThiamine Water leaching,oxygen,heat,

light,alkaline conditionsVitamin K Light,alkaline conditionsVitamin A Heat,light,oxygenVitamin D Light,oxygen, alkaline conditions

Adequate intakes of vitamins are essential to maintain health. Many of these micronutrients are sensitive to heat, oxygen and pH (Table 3). Generally processing can lead to a decrease in the amount of these micronutrients in foods.

Figure 1: Schematic of changes in structures of starch and proteins that can arise from food processing

For example, canning can decrease vitamin C content by 70% compared with the amount in the original ingredients. Vitamin C is required to prevent scurvy and may play a role in preventing cardiovascular disease. Consequently fortification of processed foods with specific micronurients to compensate for such losses may be required.

In contrast, processing can release nutrients and bioactive compounds from the food matrix where they are bound. As a result digestibility and bioavailability may be improved compared with that achieved when consuming the non-processed primary products. A classical example is lycopene, a carotenoid found in tomatoes which may have health benefits.

Figure 2: Structures of a “normal” and trans fatty acid produced during processing.


Table 3: Effects of processing procedures on some vitamins

Rowett food reports

Nutritional Implications of Industrial Food Processing

I N S I G H T S

I N T O

S C I E N C E

The Rowett Institute of Nutrition and Health

We undertake research to address contemporary problems in nutrition, which makes a significant contribution to increased scientific knowledge, underpins Government policies and informs innovation for industry.

Garry Duthie is Professor of Nutritional Science at the University of Aberdeen. He is Head of Human Studies at the Rowett Institute of Nutrition and Health, University of Aberdeen and is also leader of the Natural Products Research Group. His research focuses on the mechanisms by which dietary factors prevent or promote the development of diseases such as heart disease and cancer.

C O N TA C T

PROF. GARRY DUTHIE

Email [email protected]


Consumption of ketchup leads to a greater and more prolonged increase in plasma lycopene concentrations than is observed when consuming tomatoes with a similar lycopene content (Fig 3). The release of lycopene from the plant cells during ketchup manufacture improves availability and subsequent absorbtion.8

ConclusionsOur consumption of industrially processed food is a recent event in relation to our evolutionary history and the consequence for our health is a matter of contentious debate. However, food processing is a fact of modern life and its continual innovations may be the only means of sustaining an ever expanding population on our planet. There are advantages (eg. improved availability, choice) and disadvantages (eg toxic compounds, nutrient losses) of processed foods. The nutritional consequences of consuming processed foods is arguably under-researched. There needs to be continual open dialogue between academic scientists and the food industry to develop processing procedures which maximise the health properties of processed foods while still being profitable and attractive to the consumer. Please do not hesitate to contact us for further information.

References1. Southgate DAT. Food processing. In Human Nutrition and Dietetics (eds Garrow JS, James WPT, Ralph A) 2000, 397-409. Churchill Livingstone.

2. Knorr D, Froehling A, Jaeger H, et al. Annu. Rev. Food Sci. Technol. 2011, 2, 203-205.

3. Somza V. Mol. Nutr. Food Res. 2009, 53, 1485-1486.

4. Hooper L, Barlet C, Davey SG, Ebrahim S. Cochrane Datbase Syst Rev 2004, 1: CD003656

5. Lichtenstein AH, Kennedy E, Barrier P et al. Nutr. Rev. 1998, 56, S3-19.

6. Eaton SB, Konner M. New Eng. J. Med 1985, 283-289.

7. Stender S, Dyerberg J, Bysted A. et al. Atherosclerosis Supplements 2006, 7, 46-52.

8. Shi J, Le Maguer M. Crtical Rev. Food Sci. Nutr. 2000, 40, 1-42



ISSUE 03 SPRING 2012Repor t author:


BackgroundFood processing converts primary animal and plant products into edible foods. The majority of food we consume in the UK has been industrially processed in some way. Processing techniques increase the stability of the product and permit the consumer to choose from a wide range of food items all year round. Some argue that without food processing methods it would be difficult for industrialised countries to sustain their populations.1 The main pressure on food processors is to return a profit. Unsurprisingly, there is a tendency to focus on producing foods which appeal to the customer in terms of taste, visual appeal and price. Such foods may be sub-optimum from a nutritional standpoint and may not be compatible with current health messages. This brief report summarises current industrial food processing procedures and discusses the consequences for the nutritional value of food.

Methods of food processingTraditional methods of food processing such as sun drying, oven drying, smoking, salting, pickling and fermenting require little equipment. Such procedures reduce microbiological activity and in the pre-industrial era allowed foods to be stored against times of scarcity. Early technological innovations to preserve food were canning (early 1800s), pasteurisation (1860s), freeze drying (early 1900s) and deep freezing (1920). These methods are still in use today. However, there are now a whole range of newer technologies employed by the food industry to provide palatable, safe food. These include

• the use of modified atmospheres• the addition of preservatives (eg sulphites, benzoates, nitrites)• the control of microstructure (eg emulsions, matrices, extrusions)• manothermosonication (combined ultrasonics, heat and pressure)• irradiation• the use of high magnetic field pulses• electroporation (high voltage electric gradient pulses)

Figure 3: Schematic of how processing of tomatoes to form ketchup improves uptake of lycopene, a plant carotenoid.

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Rowett food reports - The University of Aberdeen · Rowett food reports ... choice) and disadvantages (eg toxic compounds, nutrient losses) of processed foods. ... (hurdle technology)