From Farm to Fork

Effect of thermal treatment on food nutrient content

Water soluble vitaminsWater soluble vitamins

Gioacchino DELL'AQUILA - Food Engineering Master Program

ISTANBUL AYDIN UNIVERSITY - TURKEY

Heat treatmentAdvantages vs disadvantages

• Control of processing conditions

• Capability to produce shelf-stable food

• No refrigeration required in most of the cases

• Destruction of anti-nutritional factors

• Improvement in the availability of some nutrients

• Improvement of safety

(contd)

• Alteration or destruction of food component

• Change in texture, flavour, taste, colour

• Product may burn or overcook

• Loss of nutritional value

• Less destructive processing methods exist

Water-soluble vitamins

Vitamin B complex

group of compounds soluble in aqueous solution including Thiamine (B1), Riboflavin (B2), Niacin (B3), Pantothenic acid (B5), Cyanocobalamin (B12) and Vitamin B6 (pyridoxal, pyridoxine or pyridoxamine).

Biotin, Lipoic acid and Folic acid and Ascorbic acid are also part of the water-soluble vitamins.

Tab.1 Major food sources of water-soluble vitamins

Ascorbic acid

Formation of collagen, wound healing; maintaining blood vessels, absorption of iron, calcium, folacin; production of brain hormones and immune factors; antioxidant

Most unstable under heat, drying, storage; very soluble in water, leaches out of some vegetables during cooking; alkalinity (baking soda) destroys vitamin C

ThiaminHelps release energy from foods; promotes normal appetite; important in function of nervous system

Losses depend on cooking method, length, alkalinity of cooking medium; destroyed by sulfite used to treat dried fruits such as apricots; dissolves in cooking water.

Riboflavin Helps release energy from foods; promotes good vision, healthy skin. Sensitive to light; unstable in alkaline solutions.

NiacinEnergy production from foods; aids digestion, promotes normal appetite; promotes healthy skin, nerves.

-

Vitamin B6Aids in protein metabolism, absorption; aids in red blood cell formation; helps body use fats.

Considerable losses during cooking.

Folic AcidAids in protein metabolism; promotes red blood cell formation; prevents birth defects of spine, brain; lowers homocystein levels and thus coronary heart disease risk.

Easily destroyed by storing, cooking and other processing.

Pantothenic Acid

Involved in energy production; aids in formation of hormones

bout half of pantothenic acid is lost in the milling of grains and heavily refined foods

Biotin Helps release energy from carbohydrates; aids in fat synthesis -

Organic Function Stability in food

Processing by application of heat

• Heat processing using steam or water

– Blanching

– Pasteurisation

– Heat sterilisation• In container sterilisation

• UHT / aseptic processes

– Evaporation and distillation

– Extrusion

(contd)

• Heat processing using hot air• Dehydratation

• Baking and roasting

• Heat processing using hot oils• Frying

• Heat processing using direct and radiated energy

• Dielectric heating

• Ohmic heating

• Infrared heating

Blanching

Handling raw food for further processing

Pre-treatment prior to • Heat sterilisation

• Dehydratation• Freezing

- Conventional steam blanching- Conventional hot water blanching- Microwave Blanching

Steam blanching + cooling Smaller loss in water soluble components Smaller volumes of waste Nutrient losses reduced by pre-conditioning (hot air treatment prior to blanching)

Cold air - Higher nutrient retention, loss of weightRunning water (fluming) – losses due to leaching

Individual quick blanching (IQB)

Factors influencing vitamin loss in blanching

Leaching, oxidation, thermal destruction

Preparation method used : cutting, slicing,

dicing

Surface area/volume of food

Method of blanching and cooling

Time/Temperature

Quality, variety and seasonality of food

Tab.2 Effect of blanching method on ascorbic acid content in selected food

Rate of ascorbic acid loss is influenced also by several factors:•PH,•metals as copper or iron, •enzymes, •presence of oxygenTime / Temperature

Pasteurisation

Goals:

• Minimisation of foodborne illnesses

• Extention of shelf-life

• Destruction of spoilage microorganism

• Enzyme inactivation

Mild heating treatment reduce components loss

but

HTST (flash pateurisation) vs Holder ProcessingApplying high temperature / short time • Best retention of nutrients• Less changes in flavour• Destruction of microorganism• Inactivation of enzyme

Scientific literature reports -10 -20% of vitamin C • reduced by deareation and proper choice of

packaging (glass better than plastic or paper)

Tab.3 Vitamin losses during pasteurisation of milk (Food processing technology, 2000)

Heat sterilisationInactivation of enzymesDescruction of microbiological activities Food spoilage Foodborne diseases

Commercial standard (10% of viable organism)Shelf-life > 6 months Adequate storage requiredRefrigeration not needed

Changes in nutritional and sensory quality of food

In-container sterilisation

time is affected by

Heat resistence of target enzyme or microb

Rate of Heating (saturated steam, hot water)

Material and size of packaging

pH, physical state of food

Ultra High Temperature

Food is sterilised before filling containersAtmosphere is sterile (aseptic processing)

Different behaviour of low acid and acid food

In Low acid food Thiamin (50-75%) and Pantothenic acid (20-35%)

and Vitamin C show relevant losses

In Acid food Riboflavin, Vitamin C and Pantothenic acid likely to be loss

Tab.4 Loss of vitamins in canned and bottled food

UHT processed vegetables and meat productsThiamin and Pyridoxin lossOther vitamins are largely unaffected

UHT processed milkRetention of Riboflavin, Pantothenic acid, Niacin

In- bottle sterilised milkVitamin C (-90%), Pirydoxin (-50%), Folacin (-50%)

Tab.5 Changes in nutritional value of milk after UHT and in bottle sterilisation

Supply Chain, Storage and Shelf-life

Time that a food lasts a acceptable and safe product in distribution (Storage, Marketing, Home)

• Abiotic spoilage (Light, Moisture, Oxygen, Temp.)

• Prediction of conditions the food will be exposed

• Choose of a proper packaging

Consumer expectationAppearance, colour, aroma, enjoyability, price,

safety, nutritional value

Research for more efficient technology to satisfy the demand

Development of new trends (product)

Are these technologies enough efficient to overcome and to supply

the market needs?

References

Fellows, P., 2000. Food processing technology. Principles and practice.

Da-Wen Sun, 2005. Emerging technologies for food processing

Berk, Z., 2009. Food process engineering and technology

Brennan, J.G., 2006. Food processing handbook

Sihna, N.K., 2011. Handbook of vegetable and vegetable processing

Balasundaram G., et al., 2004. Nutrition and dietetics

Kilcast, D., Subramaniam, P., 2000. The stability and shelf-life of food

Thank you for your attention