Agriculture Reference
In-Depth Information
no means always wholly benign, and may depend on the quantities ingested
(Trewavas and Stewart, 2003). Therefore, we must be open to the possibility of
negative effects as well positive benefits to health. There are few reports of
disbenefits from alliums, apart from the introduction of unwanted taint or
flavour into milk from cows eating them.
Partly because of the multiple aspects of the potential health benefits, it is
difficult, if not impossible, to make specific, predictive, quantitative and
universally true statements on this subject. There remains, therefore, much
potential for further research to clarify this subject. It is clearly a complex field,
but we can say with certainty to those that grow and market allium vegetables
that these have great potential for prevention and even cure of many of the
diseases prevalent in modern societies. The message to consumers is simple:
just eat plenty of alliums (and other vegetables) for your health's sake.
Introduction
A number of manufactured products are produced from alliums for use in
cooking, the formulation of processed food or as medicines. The utilization of
alliums in food manufacture has been reviewed by Fenwick and Hanley
(1990b), and will only be outlined briefly here. The flavour of processed onion
and garlic products is generally rather weaker than an equivalent quantity of
the fresh product. Also, the flavour is somewhat different from the fresh product.
Loss of flavour can result from the rapid destruction of the alliinase enzyme
during processing, or from the destruction of flavour precursors. The
composition and spectrum of the flavour-determining volatiles derived from
onions or garlic depends very much on the temperature, timing and duration of
various cooking and manufacturing processes (Lancaster and Boland, 1990).
An increasing volume of allium vegetables are being sold as partially processed
fresh produce, either alone or in mixed packs with other produce. The section on
'Green Onion Storage' in Chapter 7 describes aspects of this technology.
Concentrated flavour oils
Concentrated oils can be used to impart the flavour of onions or garlic to
processed foods without the difficulties of handling a large bulk of fresh bulbs.
Onion oil and garlic oil are produced by boiling a mixture of the minced bulbs
after allowing it to stand for several hours and extracting the oils from the
condensed steam, a process known as steam distillation. Yields of 0.002-0.030 g
of onion oil/100 g of fresh bulbs, or 0.10-0.25 g of garlic oil/100 g of fresh bulbs,
are obtained.
