Magdalena Martínez-Tomé

Antioxidant Properties of Mediterranean Spices Compared with Common Food Additives

In this study, the antioxidant properties of Mediterranean food spices (annatto, cumin, oregano, sweet and hot paprika, rosemary, and saffron) at 5% concentration and of common food additives (butylated hydroxyanisole [BHA], butylated hydroxytoluene [BHT], and propyl gallate) at 100 microg/g are compared. The ability of these compounds to inhibit lipid peroxidation was, in decreasing order, rosemary > oregano > propyl gallate > annatto > BHA > sweet paprika > cumin > hot paprika > saffron > BHT. Deoxyribose damage is partially inhibited in the presence of cumin extract that exhibits the strongest protective action. The rest of the spices also protect deoxyribose better than the BHA and BHT used in the assay. Finally, the results obtained in the assay point to the prooxidant effect of propyl gallate. Hydrogen peroxide scavenging activity is measured by using peroxidase-based assay systems. In aqueous medium, the spice extracts show lower antioxidant activity than propyl gallate, the decreasing order being cumin > oregano > annatto > rosemary > hot paprika > sweet paprika. BHA and BHT did not scavenge H2O2 Spices are able to scavenge HOCl and protect alpha1-antiproteinase. The results indicate that rosemary and oregano are more effective HOCl scavengers than the other substances analyzed, which, in decreasing order, were propyl gallate, annatto, sweet and hot paprika, saffron, and cumin. The effect of Mediterranean food spices on the oxidative stability of refined olive oil tested by the Rancimat method was compared with common food additives during storage (72 h, 2, 4, and 6 months) at room temperature. The results showed that the spice extracts analyzed have significant stabilizing effects (P < 0.05).

Influence of Cooking Methods on Antioxidant Activity of Vegetables

The influence of home cooking methods (boiling, microwaving, pressure-cooking, griddling, frying, and baking) on the antioxidant activity of vegetables has been evaluated in 20 vegetables, using different antioxidant activity assays (lipoperoxyl and hydroxyl radicals scavenging and TEAC). Artichoke was the only vegetable that kept its very high scavenging-lipoperoxyl radical capacity in all the cooking methods. The highest losses of LOO. scavenging capacity were observed in cauliflower after boiling and microwaving, pea after boiling, and zucchini after boiling and frying. Beetroot, green bean, and garlic kept their antioxidant activity after most cooking treatments. Swiss chard and pepper lost OH. scavenging capacity in all the processes. Celery increased its antioxidant capacity in all the cooking methods, except boiling when it lost 14%. Analysis of the ABTS radical scavenging capacity of the different vegetables showed that the highest losses occurred in garlic with all the methods, except microwaving. Among the vegetables that increased their TEAC values were green bean, celery, and carrot after all cooking methods (except green bean after boiling). These 3 types of vegetables showed a low ABTS radical scavenging capacity. According to the method of analysis chosen, griddling, microwave cooking, and baking alternately produce the lowest losses, while pressure-cooking and boiling lead to the greatest losses; frying occupies an intermediate position. In short, water is not the cooks best friend when it comes to preparing vegetables.

Antioxidant Activity of Edible Fungi (Truffles and Mushrooms): Losses during Industrial Processing

The antioxidant properties of two raw truffles (Terfezia claveryi Chatin and Picoa juniperi Vittadini) and five raw mushrooms (Lepista nuda, Lentinus edodes, Agrocybe cylindracea, Cantharellus lutescens, and Hydnum repandum) were tested by subjecting these truffles and mushrooms to different industrial processes (freezing and canning) and comparing them with common food antioxidants (alpha-tocopherol [E-307], BHA [E-320], BHT [E-321], and propyl gallate [E-310]) with regard to their ability to inhibit lipid oxidation. All of the truffles and mushrooms analyzed exhibited higher percentages of oxidation inhibition than did the food antioxidants according to assays based on lipid peroxidation (LOO*), deoxyribose (OH*), and peroxidase (H2O2). Frozen samples exhibited a small reduction in free radical scavenger activity, but the results did not show a significant difference (P < 0.05) with respect to the raw samples, while canned truffles and mushrooms lost some antioxidant activity as a consequence of industrial processing. All of the raw and frozen truffles and mushrooms except frozen Cantharellus improved the stability of oil against oxidation (100 degrees C Rancimat), while canned samples accelerated oil degradation. Antioxidant activity during 30 days of storage was measured by the linoleic acid assay, and all of the samples except canned Terfezia, Picoa, and Hydnum showed high or medium antioxidant activity. The Trolox equivalent antioxidant capacity assay was used to provide a ranking order of antioxidant activity as measured against that of Trolox (a standard solution used to evaluate equivalent antioxidant capacity). The order of raw samples with regard to antioxidant capacity was as follows (in decreasing order): Cantharellus, Agrocybe, Lentinus, Terfezia, Picoa, Lepista, and Hydnum. Losses of antioxidant activity were detected in the processed samples of these truffles and mushrooms.

Evaluation of the Antioxidant Properties of Mediterranean and Tropical Fruits Compared with Common Food Additives

Several Mediterranean and tropical fruits have been analyzed in order to assess their antioxidant activity compared with that of common food additives (butylated hydroxyanisole [BHA], butylated hydroxytoluene [BHT] and propyl gallate). Among Mediterranean fruits, red grape and plum were more effective (P < 0.05) scavengers of peroxyl radicals than BHA, BHT, and propyl gallate. Of the tropical fruits, banana was the most effective scavenger of peroxyl radicals. Mediterranean and tropical fruits showed very good scavenger activity against hydroxy radicals (OH*), protecting deoxyribose better than BHA and BHT. The HOCI scavenging ability of Mediterranean fruits tested was, in decreasing order, lemon > plum > apricot > white grape > melon > red grape > mandarin > watermelon > peach > medlar > apple > orange > cherry > strawberry. However, the four varieties of pear were poor scavengers (P < 0.05). Among tropical fruits, the order of efficiency as HOCI scavengers was passion fruit > lime > passiflora > kumquat > avocado > pineapple > physalis > papaya fruit > carambola > mango > banana. All Mediterranean fruits showed an effect on hydrogen peroxide except peach. Tropical fruits also had a strong effect on hydrogen peroxide except avocado, which had no effect. The effect of Mediterranean and tropical fruits on the protection factor of refined olive oil, analyzed by the Rancimat method and compared with common food additives, was clear. Watermelon conferred a significantly (P < 0.05) greater protection than the other Mediterranean fruits. Among tropical fruits, physalis had the most stabilizing effect.

Improving the control of food production in catering establishments with particular reference to the safety of salads

Abstract Food production in four school kitchens was checked in order to improve food safety by establishing a self-regulated control system based on good manufacturing practices (GMPs) and as an introduction to hazard analysis and critical control points (HACCP). A form, which referred to different aspects such as the cleanliness of the installations, personnel hygiene and the prevention of cross-contamination, was used to obtain the necessary data. Furthermore, foods thought to be of high risk were periodically collected for microbiological analysis. Samples for microbiological examination were taken from cutting boards, tables, machines, knives and ingredients (on-line sampling). We used the results as a basis to train foodhandlers to improve the safety of salad preparation, in accordance with GMPs, observing that hygiene improvement depended on chlorine levels in the rinsing water. We also designed several controls for raw materials, cold storage, freezers and available chlorine levels in water. At the end of the study period, we observed a decrease in microbial populations of examined samples, which indicated that the knowledge of hygiene practices on the part of foodhandlers represents a critical control point, as defined by the EC Directive 93/43/EEC on Hygiene of Food Stuffs.

Evolution of ascorbic acid and peroxidase during industrial processing of broccoli

The ascorbic acid content and peroxidase activity of raw, canned and frozen (after blanching times of 60, 90, 120 and 150 s) broccoli florets and stems were determined. The ascorbic acid content represented 1.12 and 0.78 g kg−1 fresh weight in raw florets and stems respectively. After blanching (for different times) and freezing, the ascorbic acid content decreased to values of 0.55–0.56 g kg−1 fresh weight in florets and 0.35–0.36 g kg−1 fresh weight in stems. The industrial processing involved in canning decreased the ascorbic acid content to 0.18 g kg−1 fresh weight in florets. The peroxidase activity observed in the florets and stems of raw broccoli was 308.8 and 278.6 µmol min−1 per 100 g fresh weight respectively. The peroxidase activity remaining in frozen florets varied from 0.9 to 0.2%, while that in stems showed values of between 7.5 and 8.4%. These values for stems were within the range recommended for residual activity after blanching and freezing. The peroxidase activity of canned broccoli florets was practically undetectable. © 2000 Society of Chemical Industry

Simple phenolic composition, flavonoid contents and antioxidant capacities in water-methanol extracts of Tunisian common date cultivars (Phoenixdactylifera L.)

The purpose of this study was to determine and compare the phenolic acid composition, flavonoid content and antioxidant activity of fruits from common date cultivars. The simple phenolic content ranged from 15.73 (Mermella variety) to 54.66 mg/100 g fresh weight (Korkobbi variety). Korkobbi had also the highest content of total flavonoids (54.46 quercetin equivalents/100 g fresh weight). The percentage of inhibition can reach 83% in the lipoperoxyl radical of the Korkobbi variety, while it was about 95% with the Rotbi variety for OH·. The Trolox equivalent antioxidant capacity value provided a ranking in decreasing order at 6 min: Korkobbi > Bouhattam > Baht = Smiti > Bekreri = Garn ghzal > Mermilla = Kenta > Nefzaoui = Rotbi. It seems that the highest level of flavonoids in the Korkobbi variety was principally responsible for the highest antiradical efficiency of this cultivar.

Extending the shelf-life and proximate composition stability of ready to eat foods in vacuum or modified atmosphere packaging

Abstract The stability of the proximate composition (moisture, proteins, lipids and ash) and the microbiological state of cooked ‘ready to eat’ foods in vacuum or modified atmosphere packaging were examined and compared with conventionally packaged (in air) foods. The study was carried out for 7 and 29 days, during which time the food products were stored at 3°C. Vacuum or modified atmosphere packaging were effective for prolonging the shelf-life of the studied products up to 29 days with minimal changes in the proximate composition. Aerobic mesophilic, psychrotrophic microrganisms, and yeasts and moulds increased with time regardless of packaging type but more rapidly under conventional packaging.

Proximate composition and vitamin E levels in egg yolk: losses by cooking in a microwave oven

The proximate composition, fatty acid and tocopherol levels of egg yolk were determined in raw eggs and after different cooking processes: boiling for 3 and 10 min, heating in a microwave oven, and frying. Of the protein, lipid, ash and moisture contents, only the last decreased with microwave cooking. The predominant fatty acid was oleic (18:1) (36.10–42.6%), followed in decreasing amounts by palmitic (16:0), linoleic (18:2), linolenic (18:3) = arachidonic(20:4) = docosanoic (22:0), docosahexanoic (22:6) and myristic acid (14:0). Of the polyunsaturated fatty acids, 18:2, 18:3, 20:4 and 22:6 decreased in the samples subjected to microwaves. α-Tocopherol (6.1–2.9 mg per 100g) was the predominant isomer in all the samples followed by (β + γ)-tocopherol and δ-tocopherol, while α-tocotrienol was detected in trace amounts. All these tocopherols were reduced during cooking by up to 50% in omelettes and microwave treatments. © 1999 Society of Chemical Industry

Effect of industrial processing on chlorophyll content of broccoli

Chlorophylls a and b and pheophytins a and b were quantitaty determined in raw, frozen (after blanching for 60, 120 or 150 s) and canned florets and stems of broccoli. The chlorophyll a and b contents were 0.11 and 0.043 g kg−1 fresh weight respectively in raw florets and 0.036 and 0.018 g kg−1 respectively in stems. About 37.8% and 61.1% losses were incurred during the freezing process in florets and stems respectively, and 98.5% after canning as a consequence of industrial processing. After different blanching times the losses of chlorophyll a in frozen florets varied between 17.7 and 66.4%, while the losses of chlorophyll b varied between 23.2 and 48.8%. In the losses ranged from 55.5 to 75% and from 50 to 88.9% for chlorophylls a and b respectively. These losses resulted in an increase in pheophytin a and b levels in both florets and stems. © 2000 Society of Chemical Industry