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Structure engineering to control carotenoid bioaccessibility in fruit and vegetable based food products


Key words carotenoids, in vitro bioaccessibility, structural characteristics, pectin, pectin properties, texture, thermal processing, pretreatments, fruits, vegetables
Latest version 2011/09/06
Completed by KU Leuven LFT

How does it work?

Primary objective Structural characteristics of fruit and vegetable based food products determine to a large extent the bioaccessibility of lipophilic micronutrients such as carotenoids. Structure engineering through processing can be used as a tool to improve carotenoid bioaccessibility of fruit and vegetable based food products. Here, the example of thermal processing is given.
Working principle Carotenoid bioaccessibility can be defined as the fraction of the ingested carotenoids that is released during digestion and thus becomes available for absorption. It is typically determined by in vitro digestion models, mimicking human digestion in vitro [1]. A high carotenoid bioaccessibility is a prerequisite for a good carotenoid bioavailability, but the latter is also determined by other factors (health, age, ...).

In plant cells, carotenoids are located intracellularly in cell organelles and they are surrounded by various (structural) barriers (cell wall, cell membrane, organelle membrane, lipoprotein sheet) [2], which may hinder the release of carotenoids during digestion. Structural modifications of the plant tissue are known to take place during e.g. thermal processing. They include effects on the cell membrane (membrane disruption and associated loss of turgor), on organelle membranes and on the cell wall. Next to hemicellulose and cellulose, pectin is a cell wall polysaccharide which plays an important role in determining the structural characteristics of the plant tissue [3]. Thermal processing, for example, affects pectin and its properties and by selective pretreatments (e.g. blanching at low temperature, Ca2+-soaking,…), the structure and properties of pectin can be influenced prior to the actual thermal process [4]. Fruit and vegetable based food products with an optimised carotenoid bioaccessibility can thus be obtained by controlling thermal processing conditions (temperature and time) and thus the extent of structural degradation of the fruit and vegetable tissue (i.e. affecting the barriers surrounding the carotenoids). Next to this, the addition of fat or oil to the food product can further increase carotenoid bioaccessibility due to a higher carotenoid solubilisation during digestion.
An acceptable balance between the structural characteristics of the plant tissue and the carotenoid bioaccessibility should be strived for. Next to this, attention should be paid to carotenoid oxidation and isomerisation reactions, which will take place during thermal processing of fruit and vegetable based food products. To illustrate this principle, the relation between the β-carotene bioaccessibility and the hardness/texture (expressed as compression force) of thermally processed carrot discs is depicted in the figure below. It is clear that an inverse correlation between carrot hardness and β-carotene bioaccessibility can be observed for thermally processed carrot discs [5]. Structure-bioaccessibility.jpg

Additional effects From a nutritional point of view, thermal processing of fruit and vegetable based food products may result in an increased degradation of carotenoids due to oxidation and isomerisation [6, 7]. Whether this increased carotenoid degradation is beneficial or detrimental for the nutritional quality depends on several factors such as the carotenoid type and the food product that is considered.
Important process parameters time, temperature
Important product parameters carotenoid profile, carotenoid content, structural characteristics (e.g. hardness, viscosity, pectin properties,…)

What can it be used for?

Products In the first place, this tool is designed for carrots, tomatoes, ... (i.e. fruit and vegetable based food products which are important contributors to the carotenoid intake through the human diet).

However, the technology of structure engineering to control (other) micronutrient bioaccessibility might also be applicable to other types of food products.

Solutions for short comings Increasing carotenoid bioaccessibility of plant based food products through thermal processing, implies that the structural characteristics of the food product are altered. In case specific textural or rheological properties of food products are of key importance for food industry or for consumers, special attention should be paid to this issue. Moreover, isomerisation and oxidation reactions can take place during thermal processing, which may lead to a reduced product quality.

Therefore, thermal processes should intelligently be designed resulting in food products with a possibly sub-optimal but acceptable quality, both at structural and nutritional level.

What can it NOT be used for?

Products Whether this technology is applicable to other food products, depends on the food product itself and on the micronutrient that is considered.
Operations Structure engineering of plant based food products through other processing techniques can be performed (e.g. high pressure (pre)processing). The effects of these techniques on carotenoid bioaccessibility should be investigated. Expected is that processing techniques that do not strongly alter the structure of the food do not have a significant beneficial effect on the bioaccessibility of carotenoids.
Other limitations In order to get a good control over the carotenoid bioaccessibility, fruit and vegetable matrices should in advance be characterised in terms of their structural properties.
Risks or hazards None


Maturity Studies using the technology of structure engineering through thermal processing to influence carotenoid bioaccessibility have been reported on laboratory scale as well as on pilot scale (e.g. [5], [8], [9], [10]). Scale-up problems are not likely to be expected.
Modularity /Implementation No direct changes to production lines or other specific requirements are needed to implement this technology. In contrast, the knowledge of this technology should be used to optimise product and process factors prior to the actual thermal process, so that it can result in fruit and vegetable based food products with an optimised carotenoid bioaccessibility. Here it is of importance to keep in mind the inverse relation between carotenoid accessibility and structural integrity.
Consumer aspects Consumer acceptance is expected to be high, since the technology may deliver fruit and vegetable based food products with a high nutritional value. On the other hand, the consumer might also have specific expectations with regard to the structure of the food.
Legal aspects No information is available, please check local legislation.
Environmental aspects Environmental aspects related to processing techniques that are currently being used, are also applicable to this technology.

Further Information

Institutes KU Leuven LFT, IFR, Chalmers University of Technology, University of Massachusetts Amherst
References 1. Parada, J., Aguilera, J.M. (2007). Food microstructure affects the bioavailability of several nutrients. Journal of Food Science, 72, 21-32.

2. Vishnevetsky, M., Ovadis, M., Vainstein, A. (1999). Carotenoid sequestration in plants: the role of carotenoid-associated proteins. Trends in Plant Science, 4, 232-235.

3. Waldron, K.W., Smith, A.C., Parr, A.J., Ng, A., Parker, M.L. (1997). New approaches to understanding and controlling cell separation in relation to fruit and vegetable texture. Trends in Food Science and Technology, 8, 213-221.

4. Sila, D.N., Smout, C., Vu, S.T., Van Loey, A., Hendrickx, M. (2005). Influence of pretreatment conditions on the texture and cell wall components of carrots during thermal processing. Journal of Food Science, 70, E85-E91.

5. Lemmens, L., Van Buggenhout, S., Oey, I., Van Loey, A., Hendrickx, M. (2009). Towards a better understanding of the relationship between the β-carotene in vitro bio-accessibility and pectin structural changes: A case study on carrots. Food Research International, 42, 1323-1330.

6. Lemmens, L., De Vleeschouwer, K., Moelants, K., Colle, I., Van Loey, A., Hendrickx, M. (2010). β-Carotene isomerization kinetics during thermal treatments of carrot puree. Journal of Agricultural and Food Chemistry, 58, 6816-6824.

7. Boon, C.S., McClements, D.J., Weiss, J., Decker, E.A. (2010). Factors influencing the chemical stability of
carotenoids in foods. Critical Reviews in Food Science and Nutrition, 50, 515-532.

8. Colle, I., Van Buggenhout, S., Van Loey, A., Hendrickx, M. (2010). High pressure homogenization followed by thermal processing of tomato pulp: Influence on microstructure and lycopene in vitro bioaccessibility. Food Research International, 43, 2193-2200.

9. Lemmens, L., Colle, I., Knockaert, G., Van Buggenhout, S., Van Loey, A., Hendrickx, M. (2011). Influence of pilot scale in pack pasteurization and sterilization treatments on nutritional and textural characteristics of carrot pieces. Food Research International, in press, doi:10.1016/j.foodres.2011.02.030.

10. Colle, I., Andrys, A., Grundelius, A., Lemmens, L., Löfgren, A., Van Buggenhout, S., Van Loey, A., Hendrickx, M. (2011). Effect of pilot-scale aseptic processing on tomato soup quality parameters. Journal of Food Science, 76, C714-C723.

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Created by LiesbethV on 22 September 2011, at 19:53