STABILIZATION OF MEAT LIPIDS WITH GROUND SPICES

FEREIDOON SHAHIDI, RONALD B. PEGG and ZAN 0. SALEEMI

Department of Biochemistry Memorial University of Newfoundland

St. John’s, Newfoundland, Canada, A l B 3x9

Received for Publication May 31, 1995 Accepted for Publication July 3, 1995

ABSTRACT

f i e antioxidant ejjicacy of ground clove, ginger, oregano, rosemary, sage, and thyme was investigated in comminutedpork systems. Spices at 200-2000ppm levels of addition inhibited the formution of the 2-thiobarbituric acid (TBA) reac- tive substances (TBARS) by 12-96% over 21-days of storage at 4C. The anti- oxidative effect of spices was concentration-dependent; but close followed by sage and then rosemary was most effective. Ginger and thyme exerted the least effect in prevention of oxidation of meat lipids.

INTRODUCTION

Lipid oxidation in food leads to flavor deterioration, formation of possible tox- ic products, discoloration of pigments, and loss of nutritional value arising from the destruction of fat-soluble vitamins and essential fatty acids. Addition of an- tioxidants to meat and meat products results in their quality preservation by retar- ding autoxidation and rancidity development, as well as discoloration and loss of nutrients. The inhibitory effect of antioxidants has been attributed to the dona- tion of a hydrogen atom or an electron to a lipid free radical as well as possible formation of a complex between the antioxidant and the lipid chain (Dziezak 1986). The most commonly used synthetic antioxidants in foods are butylated hydrox- yanisole (BHA), butylated hydroxytoluene (BHT), propyl gallate (PG), and tert- butylhydroquinone (TBHQ). However, the present trend in food processing is to use natural ingredients due to increasing sensitivity of consumers to synthetic additives (Bailey 1988), and especially since BHA and BHT are suspected to have

Journal of Food Lipids 2 (1995) 145-153. All Rights Reserved. 0 Copyrighr 1995 by Food & Nutrition Press, Inc., Trumbull, Connecticut. 145

146 F. SHAHIDI, R.B. P E W and Z.O. SALEEMI

carcinogenic activity (Nakatani 1992). Thus, use of naturally-occurring anti- oxidants for retarding meat flavor deterioration (MFD) and development of warmed-over flavor (WOF) is desirable.

Spices are aromatic and pungent materials used as condiments for the coloring and seasoning of many foods. Important fractions of spices are their volatile oils and oleoresins. Volatiles of essential oils are responsible for the characteristic aroma of the spice. Their content can range anywhere from less than 1 to as much as 20% (Clark 1970). The oleoresin, which is the nonvolatile extract, is respon- sible for the typical taste and pungency of the spice. Oleoresins generally ac- count for less than 10% of the total weight of spice, and are extracted from spices by organic solvents such as acetone or ethanol which are then later removed (Clark 1970). Oleoresins may also be recovered by the use of the supercritical fluid ex- traction technique. Because spices and their extracts are used in a wide variety of foodstuffs, it is important to evaluate their individual effects on the control of lipid oxidation and rancidity development.

It has been reported that spices and herbs enhance the keeping quality of fatty foods. Thus, there has been an interest in examining the antioxidant properties of a number of spices and condiments (Chipault et al. 1956; Bishov ef al. 1977; Chang et uZ 1977; Bracco et ul. 1981; Barbut et al. 1986; Al-Jalay et ul. 1987; Mendiolea et al. 1990; Schuler 1990; Stoick et ul. 1991; Nakatani 1992). The objective of this study was to investigate the antioxidative properties of ground clove, ginger, oregano, rosemary, sage, and thyme in thermally processed com- minuted pork.

MATERIALS AND METHODS

Spices (clove, ginger, oregano, rosemary, sage, and thyme) were obtained from Griffith Laboratories (Scarborough, ON). Antifoam A, 1,1,3,3-tetramethy- oxypropane (TMP), BHT, and TBHQ were purchased from Sigma Chemical Com- pany (St. Louis, MO). 2-Thiobarbituric acid and hydrochloric acid were acquired from BDH Chemicals Inc. (Toronto, ON).

Fresh pork loins were purchased from a local supermarket and were ground twice using a Braun meat mincer (Model KGZ 3, Braun Canada Ltd., Missisauga, ON). The comminuted pork was thoroughly mixed with 20% (w/w) distilled water and 150 g portions were transferred to Mason jars. Jars were subdivided into different groups. To four sets each consisting of six jars, a single ground spice, namely clove, ginger, oregano, rosemary, sage, or thyme, at concentrations rang- ing between 200 and 2000 ppm, was added. To a seventh jar, lo00 ppm of ground sage was added but only after the pork had been thermally processed. The same batch of meat was used in all experiments. Meat samples were cooked in a ther-

STABILIZATION OF MEAT LIPIDS WITH SPICES 147

mostated water bath at 85 f 1C for 40 min. Samples were stirred by a glass rod every 5 min. After cooling to room temperature, cooked meat samples were homogenized and stored in Nasco Whirl-Pak bags (Systems Plus, New Hamburg, ON) in a refrigerator at 4C until used. Samples were withdrawn weekly over a period of 3 weeks for testing their oxidative state.

Lipid Autoxidation of the Cooked Meat

The oxidative state of thermally processed pork samples was monitored by the 2-thiobarbituric acid (TBA) test of Tarladgis et al. (1960) with slight modifica- tions as described below. Each meat sample (10 g) was transferred to a 500 ml round bottom flask to which 97.5 ml distilled HzO, 2.5 ml4N HCI, 4 glass beads, and 5 drops of the antifoam A emulsion were added. Samples were fractionally distilled until 50 ml of distillate were collected. A 5 ml portion of each distillate was combined with 5 ml of 0.02 M aqueous TBA reagent in a clean 50 ml tube. Two sets of each sample were prepared as well as a blank containing 5 ml of distilled H,O in place of the distillate.

Vials were capped and heated in a boiling water bath for 45 min. After cooling to room temperature, absorbance of the complex of TBA with TBA reactive substances (TBARS) was measured at 532 nm (Tarladgis et al. 1960) using a Hewlett Packard 8452A diode array UV-VIS spectrophotometer (Hewlett Packard Canada, Ltd., Mississauga, ON). The content of malonaldehyde equivalents, re- ferred to as TBARS, (in kg/g sample) was calculated by multiplying the mean absorbance values by a factor of 8.1. This factor was obtained using TMP as a standard. Contrary to a report by Spanier et al. (1991), only one molecule of malonaldehyde is liberated from each molecule of TMP.

Inhibition of lipid oxidation (%) was calculated from the content of TBARS of meat samples according to the following equation.

TBARS content in the presence of spice) TBARS conent in the absence of spice

% Inhibition = (1 -

RESULTS AND DISCUSSION

Table 1 presents the variation of TBARS with storage time for thermally pro- cessed pork systems containing clove, ginger, oregano, rosemary, sage, or thyme at concentrations ranging from 200 to 2000 ppm. Also included are results for the control sample and samples treated with 30 and 200 ppm of BHT and TBHQ. While BHT at 200 ppm and TBHQ at both 30 and 200 ppm were quite effective

148 F. SHAHIDI, R.B. PEGG and Z.O. SALEEMI

TABLE 1. EFFECT OF GROUND SPICES ON THE CONTENTS OF TBARS hg/g) OF THERMALLY

PROCESSED COMMINUTED PORK OVER A 3-WEEK STORAGE PERIOD AT 4C

BHT 30 1.60k0.12 3.1220.18 5.02k0.12 200 0.50k0.05 0.76k0.10 0.91k0.05 30 0.13k0.02 0.30k0.03 0.34k0.03

200 0.13f0.02 0.18*0.02 0.26k0.03

YJ 14

11.27k0.28

6.51k.O. 12 4.04k0.10 1.71f0.68

4.87k0.13 0.44*0.05 0.39k0.02 0.38k0.03

8.30k0.21 5.38k0.25 2.43k0.10 0.58k0.03

9.48k0.30 7.85k0.12 6.10kO. 15

9.58k0.27 8.45k0.13 6.88k0.12 3.76k0.18

8.47k0.20 7.76i0.29 4.50k0.12 1.32k0.05

4.73k0.10 0.98k0.10

0.38k0.02 O.JOk0.03

8.n*0.40

, 10.04~0.20

21

10.64k0.22

9.99k0.35 7.31i0.18 4.29k0.12 1.62f0.05

4.73f0.10 0.48k0.05 0.39k0.03 0.45k0.05

9.12k0.20 5.48k0.18 2.73k0.10 0.71&0.05

8.51i0.38 8.22k0.15 7.29k0.28 5.76k0.13

9.37k0.12 8.01&0.15 6.80k0.21 3.85f0.10

8.80k0.18 6.46k0.31 4.99k0.12 1.59k0.09

4.33k0.20 0.95k0.09

0.44k0.05 0.45k0.03 -

TBARS. 2-thiobarbituric acid reactive substances. Results an mean values of three replications f standard deviation.

in controlling autoxidation, some of the spices examined also possessed adequate potency in inhibiting MFD. The concentration of TBARS for spice-containing samples was considerably lower (P < 0.05) than the control, thus indicating pro- tection of meat by these spices against oxidation. Furthermore, this protection was concentrationdependent. Sage, rosemary, oregano and especially close ap- peared to be most effective in retarding lipid autoxidation as reflected in their

STABILIZATION OF MEAT LIPIDS WITH SPICES 149

TBA numbers over a 3-week storage period (see Table 1). The excellent antioxi- dant activity of clove originates from its high content of gallic acid and eugenol constituents. Ginger and thyme showed the weakest antioxidative effects. The present data on relative effectiveness of spices tested are in good agreement with those reported by Cort (1974), Chipault et al. (1956), Al-Jalay et al. (1987) and Mendiolea et af. (1990). Chipault et al. (1956), reported that factors such as the physical state of the fat-water system, type of lipid, pH of aqueous system, and presence of catalysts and/or synergists, affect the stability of lipids and may in- fluence the antioxidant efficacy of spices in different foods. Chipault et al. (1956) found that sage and rosemary were more effective in lard than other spices tested, while close proved to be a powerful antioxidant in grougd pork. In mayonnaise and salad dressing, oregano had a very pronounced antioxidative effect.

The superior antioxidant activity of clove, as compared to other spices in- vestigated in this study, may arise from its high content of eugenol (3.03%) and gallic acid (1.26%), both of which are known to possess strong antioxygenic ef- fects at relatively low concentrations (Kramer 1985; Al-Jalay et al. 1987; Shahidi et al. 1992). The activity of rosemary is due to a number of potent compounds, namely carnosol, rosmanol, epirosmanol, isorosmanol, rosmaridiphenol, rosmari- quinone as well as carnosic and rosmaric acids (Chang et al. 1977; Houlihan et al. 1984; Schuler 1990). Presence of carnosol and carnosic acid in sage has also been reported (Brieskorn et al. 1964; Wenker et al. 1965). Oregano, on the other hand, contains caffeic, rosmaric, and protocatechuic acids, as well as a phenyl glucoside, and a newly recognized antioxidant, 2-caffeoyloxy-3-[2-(4-hydroxy- benzoyl)-4,5-dihydroxy]phenylpropionic acid (Kikuzaki and Nakatani 1989), as its active antioxidant components. Curcumin was found to be the active antioxidant of thyme (Al-Jalay et af. 1987), but recently a number of other phenolic com- pounds have been identified as natural antioxidants in thyme (Nakatani 1992). While ginger rhizome has been known to possess an antioxidant action, its active components were not known (Lee et al. 1986). However, a recent study by Nakatani (1992) has identified a number of components having the general chemical structure related to curcumin itself, or without the second ring with keto, hydroxy and related substitutes in ginger. The chemical structure of some active components of the spices examined are presented in Fig. 1.

Sage added to meat after cooking had a much lower (=30-40% less) anti- oxidative effect than when it was incorporated into meat prior to thermal pro- cessing. This is perhaps due to partial oxidation of meat lipids during cooking. According to Pruthi (1980), numerous investigators have shown that addition of many biological systems to a fat followed by heat treatment produce fat-stabilizing substances. If, in fact, these fat-stabilizing substances were formed during ther- mal processing, lower TBA values of the meat sample treated with sage before cooking could be justified.

150 F. SHAHIDI, R.B. PEGG and Z.O. SALEEMI

HO

H o a c m H

Protocatechuic Acid

H o H b C o o H

HO

Gallic Acid

CdeicAcid

Eugenol

COOH

\ OH Roemaric acid

OH

Carnosic acid Rosddiphenol

FIG. 1 . CHEMICAL STRUCTURE OF ANTIOXIDANT COMPONENTS OF SELECTED SPICES

Three dimensional graphs shown in Fig. 2 exhibit the relative inhibition of TBARS formation of thermally processed comminuted pork over a 3-week storage period at 4C for different application levels of each ground spice. A close scrutiny of the results presented in Table 1 and Fig. 2 shows that spices tested inhibited oxidation of meat lipids in the following order:

STABILIZATION OF MEAT LIPIDS WITH SPICES

‘‘B p f - L \

\

151

152 F. SHAHIDI, R.B. P E W and 2.0. SALEEMI

clove > sage > rosemary = oregano > thyme = ginger

Thus, in addition to their usual flavoring effects in foods, spices may have prac- tical significance for inhibiting oxidative deterioration and enhancing the keep- ing quality of meat products.

ACKNOWLEDGMENTS

We are grateful to the Natural Sciences and Engineering Research Council (NSERC) of Canada for financial support.

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