JFS:FoodChemistryandToxicology
Evaluation of the Antioxidant Effects of Dried
Milk Mineral in Cooked Beef, Pork, and Turkey
D.P. CORNFORTH AND E.M. WEST
ABSTRACT: This study was done to determine the optimum level of dried milk mineral (MM) to inhibit lipid oxida-
tion in various ground meats. Cooked ground beef and pork required 2% MM to maintain thiobarbituric acid (TBA)
values < 1.0 after 14 d refrigerated storage, compared to 1% MM for ground turkey.TBA values of cooked ground beef
were lower (p < 0.05) when MM was added in water suspension, rather than as a dry powder. Among MM components
(phosphate, calcium, and citrate), polyphosphates most effectively maintained low TBA levels during storage. MM
probably chelates soluble iron to colloidal calcium phosphate particles, thus removing iron as a catalyst for lipid
oxidation.
Keywords: antioxidant, TBA, milk, phosphate, meat
Materials and Methods
Introduction
N COOKED MEATS, OFF-FLAVOR DEVELOPMENT ASSOCIATED WITH
lipid oxidation is one of the major limitations to extended
Experimental design and statistics
I
Dried milk mineral (MM) was added to raw ground beef,
pork, or turkey at 0% (control), 0.25%, 0.50%, 1.0%, and 2.0%
of meat weight. After cooking, lipid stability was measured
using the thiobarbituric acid (TBA) test described by Buege
and Aust (1978). TBA measurements were taken after 1, 4, 7,
and 14 d of storage at 2 °C. Three replications were done on
separate days for each meat. All measurements were per-
formed in duplicate. A second experiment was done to com-
pare TBA values of cooked ground beef as affected by the
method of MM addition (dry powder or a 10% suspension in
water). A third experiment was done to compare antioxidant
activity of MM components (phosphate, calcium, and cit-
rate) when added to ground beef at levels equivalent to those
found in 1% MM. Experiments 2 and 3 were replicated twice
on separate days, and TBA values were measured in dupli-
cate after 1, 5, 9, and 14 d of storage.
Treatment means were calculated by analysis of variance
(ANOVA), using StatisticaTM (Statsoft Inc., Tulsa, Okla.,
U.S.A.). Significant differences between means were deter-
mined by calculation of Fisher’s least significant difference
(LSD) values, when appropriate. Significance was defined at
p < 0.05. Figures were prepared using the curve-smoothing
feature of the CricketTM 1.01 graphics program (Computer
Associates International, Islandia, N.Y., U.S.A.).
shelf life. Warmed-over flavor (WOF) is the term used to de-
scribe the stale or rancid flavor and odor that develops in
cooked meats during storage and reheating (Tims and Watts
1958; Younathan 1985). Unsaturated fatty acids in the mem-
brane phospholipid fraction are particularly susceptible to
oxidation (Igene and Pearson 1979). Thus, even lean meats or
poultry will develop off-flavors during storage after cooking.
A major pro-oxidant factor is soluble ionic iron (Igene and
others 1979; Miller and Aust 1989), derived from the heat
degradation of heme pigments (Igene and others 1979; Bu-
chowski and others 1988). Metal chelating agents, sodium ni-
trite, and various reductants inhibit lipid oxidation when
added to cooked ground beef (Sato and Hegarty 1971; Igene
and others 1979).
Barley flour and wild rice have been shown to reduce
oxidation and extend shelf life of cooked ground beef pat-
ties (Katsanidis and others 1997). The active antioxidant
fraction in barley flour is vitamin E and related tocot-
rienols, which can reduce lipid peroxy radicals and inter-
rupt the propagation step of lipid oxidation. Wild rice con-
tains phytate (Wu and others 1994), a type II antioxidant
capable of chelating metal ions and thus inhibiting metal
catalysis of lipid oxidation (Katsanidis and others 1997).
Phytate has strong antioxidant activity in cooked chicken
(Empson and others 1991) or beef (Lee and others 1998),
but it is too expensive in its purified form for commercial
use at present.
Sample preparation
Raw ground beef, pork, and turkey (7%, 23%, and 20% fat,
Whey is another natural food ingredient with antioxidant respectively, as indicated on the label) were purchased local-
activity (Colbert and Decker 1991; Browdy and Harris 1997), ly and cooked the same day. Dried milk mineral (Lactoval
due to the presence of protein sulfhydryl groups with reduc- QTM and TruCalTM) were obtained from DMV Intl. (Fraser,
ing abilities, and also due to iron chelation by whey proteins N.Y., U.S.A.) and Glanbia Foods (Twin Falls, Ida., U.S.A.) re-
(Tong and others 2000). Interestingly, calcium ions reduce spectively. Dried MM was a white, free-flowing powder that
WOF in cooked chicken, apparently by displacing iron from was 92.1% mineral, 5.5% water, 1.0% lactose, 1% protein, and
phospholipid binding sites (Graf and Panter 1991). Thus, this 0.4% fat (DMV International, Fraser, N.Y., U.S.A.). The anhy-
study was done to investigate the possible antioxidant effects drous mineral complex consisted of phosphate (36.2%), cal-
of dried milk mineral (MM), a natural calcium source de- cium (24.5%), and citrate (18.6%). The MM was commercially
rived from whey, when added at various levels to ground prepared by drying the permeate obtained from ultrafiltra-
beef, pork, and turkey.
tion of whey.
© 2002 Institute of Food Technologists
Vol. 67, Nr. 2, 2002—JOURNAL OF FOOD SCIENCE 615