Chemistry Reference
In-Depth Information
animal fats and oils and low-fat snack foods, to name a few examples.
Antioxidant efficacy is due to many factors, but their structure, solubility and the
properties of the matrix that they are operating in, are three very important
factors. The sections below will deal with these three factors for synthetic
antioxidants and the effects they have on stabilization.
Protection of vegetable fats and oils
The treatise on synthetic antioxidants that follows is meant to be a short survey
providing leading references for the reader to follow up on for more detailed
information. BHA and BHT are less effective in vegetable oils than they are in
animal fats (Chipault, 1962), and they have no significant effect on the stability
or margarine (Tollenaar and Vos, 1958). The effect of synthetic antioxidants on
virgin olive oil aged at 65 ëC and 100 ëC provide results that are fairly typical for
other vegetable oils. In this work, the efficacy of the antioxidants was found to
be in the order of TBHQ = BHA > BHT. Similar tests done at 50 ëC had the
efficacy order: TBHQ > BHA > BHT. The efficacy was measured using
peroxide values, conjugated diene levels test and thiobarbituric acid (TBA)
absorption values (Kiritsakis et al., 1983).
Oils containing omega-3 fatty acids, such as linolenic acid, have high
nutritive value, but undergo levels of lipid oxidation that dramatically lower the
nutritive value (Addis and Warner, 1991). Synthetic antioxidants including
BHA, BHT and PG have been used to protect these unstable fatty acids, but the
safety of these synthetic materials has been questioned (Barlow, 1990).
PG has been widely used in fats and oils, meat products, confectioneries,
nuts, milk products, fish products, margarine, baked goods at levels between
0.001 and 0.04% (Madhavi and Kulkarni, 1996, Nanditha and Prabhasankar,
2009).
Protection of animal fats
Kraybill et al. (1949) reported that BHT was effective in protecting animal fats
from oxidation and that BHT was slightly more effective in lard than BHA as
measured by the AOM stability test, but not as effective as BHA when measured
in Schaal oven tests. The same researchers also reported synergism between
BHA and BHT in lard (Kraybill and Dugan, 1954). Gearhart and Stuckey (1955)
demonstrated the stabilizing effect of BHT, BHA, and PG on lard, potato chips,
crackers, and pastry. PG alone or in combination with BHT or BHA produced
the highest stability in these tests.
In the vast majority of tests, the activity of TBHQ is equivalent to or greater
than that of BHA, BHT or PG. It is most efficacious in vegetable and animal fats
and oils and has the advantage that it does not contribute to the color and odor of
the fats and oils. TBHQ is equivalent to BHA and more effective than BHT or
PG in increasing the stability of lard and is more effective than all three in
stabilizing rendered poultry fat. TBHQ is also more effective than BHT or PG in
stabilizing crude whale oil (Chahine and MacNeill, 1974) and mackerel skin
lipids (Ke et al., 1977).
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