Diepvries groente gezond?
Veel drukke mensen kiezen nogal eens voor
diepvriesgroente ipv verse groente. Finse onderzoekers wilde wel eens weten wat er
overbleef van de vitamines, mineralen, vezels en anti-oxidanten. Zij ontdekten dat
diepvriesbedrijven de groente eerst in kokend water blancheren en dan invroren. Verder
blijkt uit deze studie op 20 bekende groenten het volgende:
- Mineralen > stabiel
- Carotenoiden > stabiel
- Vitamine C > 30% verlies, dit kan toenemen tijdens opslag
- Folium zuur > 50% verlies, is belangrijke B vitamine
- phenolic anti-oxidanten en overige vitamines > 20-30% verlies
Zoals je ziet blijft verse groente de
voorkeur houden en dan het best gestoomd want door koken en met name magnetronnen (zie
studie onderaan) is het totale verlies aan voedingswaarde nog hoger.
Ron
Blanching and long-term freezing
affect various bioactive compounds of vegetables in different ways
Puupponen-Pimiä R, Häkkinen ST, Aarni
M, et al. . Journal of the Science of Food and Agriculture. Volume 83, Issue 14 , Pages
1389 - 1402 Published Online: 15 Oct 2003
An extensive study on the effects of
blanchinglfreezing and long-term freezer storage on various bioactive compounds of more
than 20 commonly used vegetables was performed. Effects were strongly plant
species-dependent. Contents of dietary fibre components either were not affected or
increased slightly. Minerals in general were also stable, but some losses of soluble
minerals by leaching were observed. Phenolic antioxidants and vitamins were clearly more
sensitive. Significant losses (20-30%) of antioxidant activity and total phenolics were
detected in many vegetables. A qualitative HPLC profiling method for phenolic antioxidants
was developed which proved to be very useful when evaluating the complex behaviour of
phenolics during food processing. Up to one-third of vitamin C contents were lost during
blanching, and further slight losses were detected during storage. Folic acid turned out
to be very sensitive to blanching, with more than half of the vitamin being lost, but was
stable during freezer storage. Carotenoids and sterols were not affected by blanching or
freezer storage. The usefulness of the applied screening methods for evaluation of the
effects of processing on vegetables is shown.
http://cat.inist.fr/?aModele=afficheN&cpsidt=15212807
Spaanse studie naar het verlies
van vitamine C en kankerremmende anti-oxidanten bij het bereiden van brocolli.
Het totale verlies bij magnetronnen:
Vitamine C : 40%
Glucosinolates (anti-oxidanten) : 74%
Koken van broccoli zorgde voor een
verlies van 55% van de anti-oxidanten. Het stomen van broccoli echter gaf bijna geen
verlies dus adviseerden de onderzoekers
dat stomen de beste methode van bereiding is.
Total aliphatic and indole/aromatic
glucosinolates and vitamin C content (ascorbic+dehydroascorbic acid) were evaluated in the
edible portions of fresh harvested broccoli (Brassica oleracea L. var. italica) florets
(Marathon cv.) before and after cooking and in the cooking water. High pressure boiling,
steam cooking, microwaving and low pressure boiling (conventional) were the four domestic
cooking processes used in this work. Results showed great differences among the four
cooking processes and their influence on the content of glucosinolates and vitamin C.
Thus, clear disadvantages were detected when cooking in a microwave due to the high loss
of vitamin C (40%) and total glucosinolates (74%) in comparison with the rest of
treatments. High pressure and conventional boiling had a significant loss rate of total
glucosinolates (33% and 55% respectively) regarding fresh raw broccoli, due to the
leaching into the cooking water. On the other hand, steaming had minimal effects on
glucosinolates and vitamin C. Therefore, we can conclude that a large quantity of
glucosinolates and vitamin C will be consumed in steamed broccoli when compared to the
other cooking processes.
http://www.springerlink.com/content/a2v7f2vv0adxpnbd/
