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A Guide - How to get the Most From your Food.

November 03, 2015 Petina Walsh

Farming methods, different food processing techniques, food preparation, and storage and handling practices affect the quality and safety of the food we consume. This essay will discuss each of these external factors and provide guidelines to help Australians choose, store, prepare and consume foods that retain the highest possible nutrient values and which expose them to the least amount of toxicities and harmful constituents.

Farming methods include conventional, organic, biodynamic, hydroponic and genetically modified crops. Nutrient value of a food is dependent on the nutrient value and quality of the medium in which the food is grown. Karlen et al. (1997, p4) defines soil quality as “the capacity (of soil) to function”.

A comparison of biodynamic and conventional farms in New Zealand showed that the biodynamic farms maintained higher quality soil properties and were as financially viable per hectare as the adjacent conventional farms (Reganold et al 1993, p344).

Food processing techniques are used to extend the shelf life of products, improve the safety of the food and can be more convenient for the consumer. Thermal processing is an efficient method of extending the shelf life and improving the safety of food. Extending the shelf life of foods and making them available in places and at times when they would otherwise be unavailable has allowed a larger variety of nutrients to be available to the consumer. The thermal processing method however, can degrade the nutrient value of the food (Lund 1988, p. 319).

Freezing and canning certain foods may sustain their nutrient value. Rickman, Barrett & Bruhn (2007) explain that initial heat treatment of canned foods results in a loss of water soluble vitamins, however, no further nutrient loss occurs during the canning phase. Freezing food results in fewer nutrients being lost initially due to the relatively short heating time, however, further nutrients are lost during storage due to oxidation.

Food processing such as grinding, fermentation or mild heating may improve bioavailability (Parada & Aguilera 2007, p. R24). The bioavailability of carotenoids for example, is dependent on the release of the nutrient from the food matrix (Deming & Erdman 1999).

Refrigeration of food slows metabolic changes in fresh fruits and vegetables (Klein 1987, p. 183). Preparing raw fruits and vegetables will usually result in some nutrient loss due to parts of the plant being discarded, however, most fruits and vegetables retain more than 90% of nutrients if prepared, refrigerated and consumed with a few hours (Klein 1987, p. 188).

Fillion & Henry (1998) review the advantages and disadvantages of frying foods. Frying food has minimal, if any influence on the protein or mineral content. Interestingly, frying potatoes increases the resistant starch, thereby increasing the dietary fibre content. The high temperatures during frying means that the foods are cooked for short periods of time. Frying actually causes less vitamin degradation than other methods of cooking (Fillion & Henry 1998, p. 157). Fillion & Henry (1998) also consider the nutritional value of the fat that the food is being fried in. Fried foods are generally a good source of vitamin E.

Cooking food in a microwave is considered to be convenient and both time and energy efficient. Cross, Fung, & Decareau (1982) suggest that microwave cooking results in greater loss of moisture compared with conventional methods but the effects on the protein, lipid, and mineral content of the food appears to be minimal. Cross, Fung, & Decareau (1982) conclude that there is a slightly greater degradation of vitamins in microwaved foods when compared to conventional cooking methods.

Yuan et al (2009) investigated the effects on the nutrients in broccoli when steamed, microwaved, boiled and stir-fried. The results show that steaming was the only cooking method that did not cause significant nutrient losses.

The CSIRO (2015) provides guidelines for storing and handling food in the home to Australian consumers.

The CSIRO (2015) advises that meat, poultry and seafood require careful storage as the possibility of food poisoning is high and should therefore be kept in the coldest part of the fridge and for no more than three days. Unwrapped meat stays fresher for longer as the dried surface of the meat slows microbial growth (CSIRO 2015).

Freezing food at approximately -18 °C all but completely stops deterioration, however, domestic refrigerator temperatures are between -15 °C and -12 °C and therefore foods can only be stored for a few weeks without loss of quality (CSIRO 2015).

CSIRO (2015) recommend that larger cuts of frozen meat and poultry should be thawed in the refrigerator prior to cooking. Smaller cuts of meat such as steaks may be cooked from a frozen state without an increased risk of food poisoning.

It is important to either keep foods colder than 4 ° or hotter than and 60 °C to reduce the risk microbial growth (Whitney et al 2014).

The risk of foodborne illness can be greatly reduced by the correct handling, storing and cooking of food. Whitney et al (2014) recommend that the food preparation area be kept clean and cross-contamination of raw and cooked foods should be avoided.

The Department of Agriculture, Fisheries and Forestry (2013) discusses how consumers influence food culture and have a major impact on agricultural and sustainability practices.

When you consider the soil quality and therefore nutrient quality of foods grown organically or bio-dynamically (Reganold et al 1993, p344), it is recommended to buy organic produce if budget permits. Although the FSANZ Food Standards Code governs pesticide use in conventionally grown crops, an individual’s tolerance level may be lower than the standard set. (Whitney 2014, p.622).

Fresh is not always best according to Lund (1988) and Rickman, Barrett & Bruhn (2007). It is therefore recommended to buy a variety of produce including fresh, frozen and canned.

Frying foods has nutritional benefits (Fillion, L & Henry, C 1998) and steaming results in the lowest nutritional degradation (Yuan et al 2009). It is important however, to ensure the food consumed is palatable. If a person does not like steamed broccoli for example, but enjoys roasted broccoli, then by all means, eat it roasted. It is preferable to lose some nutrient value during cooking than to not consume a wide variety of food.

Choosing food grown by a variety of farming methods, using various food processing techniques and following the food preparation, storage and handling practices guidelines as discussed is the best way to ensure that foods consumed retain the highest possible nutrient values with the least exposure of toxicities and harmful constituents.

 

References

Cross, G, Fung, D & Decareau, R 1982, ‘The effect of microwaves on nutrient value of foods’, C R C Critical Reviews in Food Science and Nutrition, [online] Vol 16, no. 4, pp.355-381. http://www.tandfonline.com/doi/abs/10.1080/10408398209527340 [Accessed 7 Oct. 2015].

CSIRO 2015, ‘Handling Food in the Home’, http://www.csiro.au/en/Research/Health/Food-safety/Food-handling.aspx [Accessed 7 Oct. 2015]

CSIRO 2015, ‘Storing Food’, http://www.csiro.au/en/Research/Health/Food-safety/Storing-food [Accessed 7 Oct. 2015]

Department of Agriculture, Fisheries & Forestry 2012- 2013, ‘National Residue Survey Annual Report’, Australian Government Department of Agriculture, Canberra.

Deming, D & Erdman, J 1999, ‘Mammalian carotenoid absorption and metabolism’, Pure and Applied Chemistry, [online] Vol 71, no. 12. http://www.degruyter.com/view/j/pac.1999.71.issue-12/pac199971122213/pac199971122213.xml [Accessed 7 Oct. 2015].

Fillion, L & Henry, C 1998, ‘Nutrient losses and gains during frying: a review’, International Journal of Food Sciences and Nutrition, [online] Vol. 49, no. 2, pp.157-168. http://www.tandfonline.com/doi/abs/10.3109/09637489809089395 [Accessed 7 Oct. 2015].

Karlen, D, Mausbach, M, Doran, J, Cline, R, Harris, R & Schuman, G 1997, ‘Soil Quality: A Concept, Definition, and Framework for Evaluation (A Guest Editorial)’, Soil Science Society of America Journal, Vol 61, no. 1, p. 4. https://dl.sciencesocieties.org/publications/sssaj/abstracts/61/1/SS0610010004 [Accessed 7 Oct. 2015].

Klein B 1987, ‘Nutritional Consequences of Minimal Processing of Fruits and Vegetables’, Journal of Food Quality, [online] Vol 10, no. 3, pp.179-193. http://www.researchgate.net/publication/229612809 [Accessed 7 Oct. 2015].

Lund, D 1988, ‘Effects of Heat Processing on Nutrients’, Nutritional Evaluation of Food Processing, [online] pp.319-354. http://link.springer.com/chapter/10.1007/978-94-011-7030-7_12 [Accessed 7 Oct. 2015].

Parada, J & Aguilera, J 2007, ‘Food Microstructure Affects the Bioavailability of Several Nutrients’, Journal of Food Science, Vol 72, no. 2, pp. R21-R32. http://onlinelibrary.wiley.com/doi/10.1111/j.1750-3841.2007.00274.x/pdf [Accessed 7 Oct. 2015].

Reganold, J, Palmer, A, Lockhart, J & Macgregor, A 1993, ‘Soil Quality and Financial Performance of Biodynamic and Conventional Farms in New Zealand.’, Science, Vol 260, no. 5106, pp.344-349. http://www.sciencemag.org [Accessed 7 Oct. 2015].

Rickman, J, Barrett, D & Bruhn, C 2007, ‘Nutritional comparison of fresh, frozen and canned fruits and vegetables. Part 1. Vitamins C and B and phenolic compounds’, Journal of the Science of Food and Agriculture, [online] Vol 87, no. 6, pp.930-944. http://onlinelibrary.wiley.com/doi/10.1002/jsfa.2825/abstract?userIsAuthenticated [Accessed 7 Oct. 2015].

Whitney, E, Crowe, T, Rolfes, S, Smith, D & Walsh, A 2014, ‘Understanding Nutrition’ 2nd ed. South Melbourne: Cengage, pp.610- 628.

Yuan, G, Sun, B, Yuan, J & Wang, Q 2009, ‘Effects of different cooking methods on health-promoting compounds of broccoli’, J. Zhejiang Univ. Sci. B, [online] Vol 10, no. 8, pp.580-588. http://link.springer.com/article/10.1631/jzus.B0920051 [Accessed 7 Oct. 2015].



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