UGent campus Kortrijk, laboratorium voor voedingsmicrobiologie en biotechnologie
Abstract bachelorproef 1 2016-2017: Impact of trans-cinnamaldehyde on the enzymatic browning of iceberg lettuce
The focus of this bachelor thesis was to determine the influence of natural compounds (trans-cinnamaldehyde and chlorogenic acid) on the enzymatic browning of minimal processed fresh-cut iceberg lettuce in order to prolong the shelf life. Besides appearance and loss of desirable texture, browning is one of the fundamental factors affecting the quality loss in minimally processed iceberg lettuce and leads to an economic disadvantage. The key enzymes in this enzymatic browning process are phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO) and peroxidase (POD). A treatment of iceberg lettuce with a natural component to increase the shelf life, is a healthy alternative and might reduce the use of chemical additives in the food industry.
Iceberg lettuce was bought in a local grocery store and processed in order to obtain a homogeneous batch of midrib tissue. Lettuce samples were treated with a solution of chlorogenic acid and trans-cinnamaldehyde. Using spectrophotometrical methods, several parameters (BP and activity of PAL, PPO & POD) were monitored during 14 days of refrigerated storage in plastic bags.
Trans-cinnamaldehyde treatment was studied more in detail by microbial analysis and differentiating treatment times. Results of these experiments can be used for further optimization of the trans-cinnamaldehyde treatment in order to inhibit enzymatic browning in iceberg lettuce.
Abstract bachelorproef 2 2016-2017: Impact of mineral enhancers on the bioaccessibility of iron and zinc in fermented cereal porridges
In developing countries (like Zimbabwe), there is a low bioaccessibility of trace minerals (iron and zinc) in fermented cereal porridges, which can lead to nutrient deficiency. This low bioaccessibility is caused by the presence of mineral inhibitors (phytic acid, phenolic compounds and condensed tannins), which are naturally present in cereals. By the addition of mineral enhancers (ascorbic acid, meat factor) or by adding enzymes (phytase, laccase, tannase), the bioaccessibility of iron and zinc could be increased.
Different mineral enhancers were added to the fermented porridges in a ratio 1:3. Different spectrophotometrically methods were used to determine the amount of the mineral inhibitors. An in vitro digestion was performed to have an estimation of the mineral bioaccessibility.
The fermented slurries with mineral enhancers still have an amount of mineral inhibitors, a decrease of the phytic acid and an increase of the phenolic compounds was observed. The amount of iron and zinc was increased in the fermented slurries when mopane worm powder was added, but only a small fraction was available for uptake in the body. Adding baobab to the fermented slurries had a positive influence on the bioavailability of iron and zinc. In the cereals treated with the enzymes, phytase was the only enzyme having a positive effect in the decrease of phytic acids.
This experiment has shown that baobab and mopane worm powder were not able to increase the bioavailability of minerals in these fermented porridges. In future studies, the influence of enzymes (specially phytase) is interested to study more in detail.
Graaf Karel de Goedelaan 5
Celine Vanden Abeele