Transcriptional response of genes involved in cell defense system in human cells stressed by H2O2 and pre-treated with (Tunisian) Rhamnus alaternus extracts: Combination with polyphenolic compounds and classic in vitro assays

The ability of three Rhamnus alaternus leaves extracts on antigenotoxic and gene expression level effects was respectively investigated in a bacterial assay system, i.e. the SOS chromotest with Escherichia coli PQ37 and in human K562 lymphoblast cell line. Total oligomers flavonoids (TOF) enriched, methanol and ethyl acetate extracts were prepared from powdered R. alaternus leaves and characterized quantitatively for the presence of polyphenolic compounds. We explored the response to oxidative stress using the transcriptional profile of genes in K562 cells stressed with H2O2 after incubation with plant extracts. For this purpose, we used a cDNA microarrays containing 82 genes related to cell defense, essentially represented by antioxidant and DNA repair genes. Analysis revealed that SOD1, AOE 372, TXN genes involved in the antioxidant defense system and XPC, LIG4, POLD2, PCNA genes implied in the DNA repair system were among the most expressed ones in the presence of the tested extracts. These results were in accordance with those obtained when we tested the antigenotoxic and antioxidant effects of the same extracts with, respectively the SOS chromotest and the xanthine/xanthine oxidase enzymatic assay system. The effect of the tested extracts on SOS response induced by both Aflatoxin B1 (AFB1: 10 microg/assay) and nifuroxazide (20 microg/assay) showed that the TOF extract exhibited the highest antimutagenic level towards the indirect mutagen AFB1. Whereas ethyl acetate extract showed the highest antimutagenic effect towards the direct mutagen, nifuroxazide. None of the tested extracts induced mutagenic activity. However all the tested extracts exhibited xanthine oxidase inhibiting and superoxide anions scavenging effects. R. alaternus extracts contain compounds with significant antioxidant and antigenotoxic activities. These compounds modulate gene expression as detected by using cDNA arrays.

Anthocyanin fraction from potato extracts is cytotoxic to prostate cancer cells through activation of caspase-dependent and caspase-independent pathways

Polyphenols from fruits and vegetables exhibit anticancer properties both in vitro and in vivo and specialty potatoes are an excellent source of dietary polyphenols, including phenolic acids and anthocyanins. This study investigated the effects of specialty potato phenolics and their fractions on LNCaP (androgen dependent) and PC-3 (androgen independent) prostate cancer cells. Phenolic extracts from four specialty potato cultivars CO112F2-2, PATX99P32-2, ATTX98462-3 and ATTX98491-3 and organic acid, phenolic acid and anthocyanin fractions (AF) were used in this study. CO112F2-2 cultivar extracts and their AF at 5 mug chlorogenic acid eq/ml were more active and inhibited cell proliferation and increased the cyclin-dependent kinase inhibitor p27 levels in both LNCaP and PC-3 cells. Potato extract and AF induced apoptosis in both the cells and, however, the effects were cell context dependent. Cell death pathways induced by potato extract and AF were associated with mitogen-activated protein kinase and c-jun N-terminal kinase activation and these kinases activated caspase-independent apoptosis through nuclear translocation of endonuclease G (Endo G) and apoptosis-inducing factor in both cell lines. Induction of caspase-dependent apoptosis was also kinase dependent but was observed only in LNCaP cells. Kinase inhibitors reversed this nuclear translocation of endonuclease G and apoptosis-inducing factor. This is the first report showing that the cytotoxic activities of potato extract/AF in cancer cells were due to activation of caspase-independent apoptosis. Current studies are focused on identifying individual components of the AF responsible for the induction of cell death pathways in prostate and other cancer cell lines and developing potato cultivars that overexpress these active compounds.

Microbial load, acidity, lipid oxidation and volatile basic nitrogen of irradiated fish and meat-bone meals

Experiments were carried out to study the effect of different doses of gamma irradiation (0, 5, 10, 15 and 20 kilo gray; kGy) on some nutritive components and chemical aspects pertaining to quality of fish meal and meat-bone meal. The radiation doses required to reduce the total microbial load and Salmonella sp. one log cycle (D(10)) in fish meal and meat-bone meal were determined. Results indicated that gamma irradiation of fish meal and meat-bone meal with 5-20 kGy doses had no effects on the total acidity values but increased the values of lipid oxidation and total volatile basic nitrogen. D(10) of total microbial load and Salmonella sp. were 833 and 313 Gy for fish meal and 526 Gy and 278 Gy for meat-bone meal, respectively. It can be concluded that radiation processing could be employed in the recycling of fish and meat-bone meals by using them as feedstuffs in poultry diets with no fear of losing their nutritive components.

Microbial population, physicochemical quality, and allergenicity of molluscs and shrimp treated with cobalt-60 gamma radiation

Frozen molluscs (squid, octopuses, and cuttlefish) and crustaceans (shrimp) were irradiated using a cobalt-60 gamma source, at different doses, in order to investigate the effects of gamma radiation on their microbial population, organoleptic characteristics, lipid profile, and tropomyosin content. Irradiation of shrimp and squid with either 2.5 or 4.7 kGy reduced mesophilic bacteria contamination to low or nondetectable levels, respectively, whereas irradiation of octopus and cuttlefish with the same doses reduced the bacterial population. Irradiation treatment had no significant (P > 0.05) effect on the total lipid content and the major detected classes of polar and neutral lipids, whereas it significantly (P < 0.05) increased the contents of neutral lipids in octopus mantle and in shrimp muscle and cephalothorax samples. The total fatty acid content and the omega-3: omega-6 fatty acid ration was not affected. A dose-dependent significant (P < 0.05) decrease in the ratio of polyunsaturated fatty acids:saturated fatty acids was observed. With the increase in radiation dose, redness (a) and yellowness (b) values showed a variation, whereas the lightness (L) value was significantly (P < 0.05) decreased in mollusc mantles and shrimp muscle and increased in shrimp cephalothorax. The total of color changes ( delta E) increased (P < 0.05) as the dose increased. Significant (P < 0.05) changes in textural properties were observed with radiation treatment in octopus tentacles and in squid and cuttlefish mantle. The amount of tropomyosin, which is the major mollusc and crustacean allergen in the irradiated organisms, was reduced by gamma radiation, depending on the dose.

Feasibility of gamma irradiation as a stabilisation technique in the preparation of tissue reference materials for a range of shellfish toxins

The effect of gamma-irradiation on concentrations of hydrophilic and lipophilic phycotoxins has been investigated by use of HPLC-UV and LC-MS. Pure toxins in organic solvents and toxins in mussel (Mytilus edulis) tissues were irradiated at three different doses. In solution all toxin concentrations were reduced to some extent. Most severe decreases were observed for domoic acid and yessotoxin, for which the smallest dose of irradiation led to almost complete destruction. For pectenotoxin-2 the decrease in concentration was less severe but still continuous with increasing dose. Azaspiracid-1 and okadaic acid were the least affected in solution. In shellfish tissue the decrease in toxin concentrations was much reduced compared with the effect in solution. After irradiation at the highest dose reductions in concentrations were between ca. 5 and 20% for the lipophilic toxins and there was no statistical difference between control and irradiated samples for azaspiracids in tissue. Irradiation of shellfish tissues contaminated with domoic acid led to a more continuous decrease in the amount of the toxin with increasing dose. The effect of irradiation on the viability of microbial activity in shellfish tissues was assessed by using total viable counting techniques. Microbial activity depended on the type of shellfish and on the pretreatment of the shellfish tissues (with or without heat treatment). As far as we are aware this is the first investigation of the effectiveness of irradiation as a technique for stabilising tissue reference materials for determination of phycotoxins. Our results suggest that this technique is not effective for materials containing domoic acid. It does, however, merit further investigation as a stabilisation procedure for preparation of shellfish tissue materials for some lipophilic toxins, in particular azaspiracids. Chemical structures of the toxins investigated in the study.

Use of γ-irradiation to reduce high levels of Staphylococcus aureus on casein–whey protein coated moist beef biltong

Moist beef biltong strips (mean moisture content = 53.6%, NaCl content = 1.91% and a(w) = 0.979) was inoculated with Staphylococcus aureus ATCC 9441 (10(6)-10(7) cfu/g), or sprayed with distilled water (non-inoculated controls). Both non-inoculated and inoculated biltong strips were coated with a casein-whey protein (1:1) edible coating followed by irradiation to a target dose of 4 kGy. S. aureus, aerobic plate, yeast and mould counts were performed to determine the effect of gamma-irradiation and the edible coating on inoculated S. aureus and the spoilage flora of the biltong. Moisture and NaCl content, a(w) and pH measurements were also performed. None of the intrinsic properties were affected to a practically significant extent. Irradiation reduced all microbial counts (P < 0.05), i.e. inoculated S. aureus (6 log cycles), aerobic plate count (5-6 log cycles) and yeast and mould counts (1-2 log cycles). Irradiation at 4 kGy is thus effective to ensure safety of moist beef biltong, and provided that initial fungal counts are not excessive, may extend the shelf-life. The edible coating had no significant effect (P > 0.05) on microbial counts, possibly because the high moisture content of the biltong diminished its oxygen barrier properties.

Antioxidative activity of bound-form phenolics in potato peel

Free and bound-form phenolics were isolated from potato (cv. Toyoshiro) flesh and peel. The free and bound-form phenolics in the peel showed high DPPH radical scavenging activity, while those in the flesh showed low activity. The total amount of chlorogenic acid and caffeic acid in the free-form phenolics from the peel was highly correlated with the DPPH radical scavenging activity. Ferulic acid was identified as the active radical scavenging compound in the bound-form phenolics from the peel. The potato peel may therefore offer an effective source of an antioxidative.

Effect of low-dose radiation on microbiological, chemical, and sensory characteristics of chicken meat stored aerobically at 4 degrees C

The effect of gamma-radiation (0.5, 1, and 2 kGy) on the shelf life of fresh skinless chicken breast fillets stored aerobically at 4 degrees C was evaluated. Microbiological, chemical, and sensorial changes occurring in chicken samples were monitored for 21 days. Irradiation reduced populations of bacteria, i.e., total viable bacteria, Brochothrix thermosphacta, lactic acid bacteria (LAB), and the effect was more pronounced at the highest dose (2 kGy). Pseudomonads, yeasts and molds, and Enterobacteriaceae were highly sensitive to gamma-radiation and were completely eliminated at all doses. Of the chemical indicators of spoilage, thiobarbituric values for nonirradiated and irradiated aerobically packaged chicken samples were in general low (<1 mg of malonaldehyde per kg of muscle) during refrigerated storage for 21 days. With regard to volatile amines, both trimethylamine nitrogen (TMA-N) and total volatile basic nitrogen (TVB-N) values for nonirradiated aerobically packaged chicken increased steeply, with final values of ca. 20.3 and 58.5 mg N/100 g of muscle, respectively. Irradiated aerobically packaged chicken samples had significantly lower TMA-N and TVB-N values (P < 0.05) of ca. 2.2 to 3.6 and 30.5 to 37.1 mg N/100 g of muscle, respectively, during refrigerated storage for 21 days. Of the biogenic amines monitored, only putrescine and cadaverine were detected in significant concentrations in both nonirradiated and irradiated chicken samples, whereas histamine formation was noted only in nonirradiated samples throughout storage. On the basis of sensorial evaluation, low-dose irradiation (0.5 and 1.0 kGy) in combination with aerobic packaging extended the shelf life of fresh chicken fillets by ca. 4 to 5 days, whereas irradiation at 2.0 kGy extended the shelf life by more than 15 days compared with that of nonirradiated chicken.

Amine degradation by 4,5-epoxy-2-decenal in model systems

The reactions of 4,5-epoxy-2-decenal with octylamine, benzylamine, and 2-phenylglycine methyl ester were studied to investigate if amines may suffer a Strecker type degradation by epoxyalkenals analogously to amino acids. In addition to other reactions, the studied amines were converted into their corresponding Strecker aldehydes (octanal, benzaldehyde, and methyl 2-oxo-2-phenylacetate, respectively) to an extent that depended on the pH, the temperature, the amount of epoxyalkenal, and the amine involved. Each amine exhibited an optimum pH for the reaction, but the corresponding Strecker aldehydes were produced to a significant extent within a broad pH range. In addition, the temperature mostly influenced the reaction rate, which was increased between 6.5 and 9.5 times when the reaction was carried out at 60 degrees C than when it took place at 37 degrees C. Furthermore, Strecker aldehyde formation was linearly correlated with the amount of the epoxyalkenal present in the reaction mixture. Nevertheless, the reaction yield mostly depended on the amine involved. Thus, octylamine only produced trace amounts of octanal, benzylamine was converted into benzaldehyde with a yield of 4.3%, and 2-phenylglycine methyl ester was converted into methyl 2-oxo-2-phenylacetate with a reaction yield of 49%. All of these results suggest that suitable amines can be degraded by epoxyalkenals to their corresponding Strecker aldehydes to a significant extent.

Effect of plant phenolics on protein and lipid oxidation in cooked pork meat patties

Rapeseed and pine bark are rich sources of phenolic compounds that have in previous studies been shown to exhibit antioxidant and anti-inflammatory properties. In this study, the antioxidant effect of rapeseed and pine bark phenolics in inhibiting the oxidation of lipids and proteins in meat was tested as a possible functional food application. The cooked pork meat with added plant material was oxidized for 9 days at 5 degrees C under light. The suitable level of plant material addition was first screened by following lipid oxidation only. For further investigations plant materials were added at a level preventing lipid oxidation by >80%. The oxidation was followed by measuring the formation of hexanal by headspace gas chromatography and the formation of protein carbonyls by converting them to 2,4-dinitrophenylhydrazones and measured by spectrophotometer. It was shown that rapeseed and pine bark were excellent antioxidants toward protein oxidation (inhibitions between 42 and 64%). These results indicate that rapeseed and pine bark could be potential sources of antioxidants in meat products.

Development of a new colorimetric method determining the yield of microencapsulation of alpha-tocopherol

Microencapsulation of alpha-tocopherol effectively protects alpha-tocopherol from oxidation and produces high-value-added and long-shelf-stable foods. High-performance liquid chromatography (HPLC) has been applied to measure the yield of microencapsulated alpha-tocopherol with high accuracy; however, it takes long analysis time. An alternative method is required to determine the yield of microencapsulated alpha-tocopherol in food industry. A new, easy, and sensitive colorimetric method using 5% cupric acetate pyridine and oleic acid was developed. Correlation coefficient (r) of colorimetric method on alpha-tocopherol in microencapsulation system and of results between colorimetric method and HPLC were +0.996 and +0.989, respectively, which indicates that this novel colorimetric method can be successfully applied to evaluate the yield of microencapsulated alpha-tocopherol instead of HPLC. The optimum storage temperature and pH of microencapsulated alpha-tocopherol for 7-day storage were 25 degrees C and pH 9, respectively, determined by this new colorimetric method.

Effect of gamma irradiation on the survival of pathogens in kwamegi, a traditional Korean semidried seafood

Kwamegi (semidried raw Pacific saury) is traditional seafood available in Korea. It has water activity in the range of 0.90 to 0.95. Spoilage and the growth of most pathogenic bacteria is retarded because of low water activity, low temperature, and packaging. However, it is contaminated with bacteria of public health significance and poses a hazard to the consumer because it is consumed raw without any cooking. The effectiveness of these hurdles in preventing the growth of Staphylococcus aureus, Bacillus cereus, Salmonella Typhimurium, and Escherichia coli and the efficacy of irradiation treatment in eliminating these bacteria from kwamegi using inoculated pack studies was examined. Radiation sensitivity of S. aureus, B. cereus, Salmonella Typhimurium, and E. coli in kwamegi was investigated. D10-values of these organisms in kwamegi were 590 +/- 13.6, 640 +/- 14.9, 560 +/- 45.4, and 550 +/- 8.6 Gy, respectively. The growth of all four test organisms inoculated into these foods during 4 weeks of storage at an ambient winter temperature (ranging from -5 degrees C to +5 degrees C) was recorded. All four pathogens (inoculated at 10(6) CFU/g) were eliminated by irradiation at 4 kGy. These studies unequivocally demonstrate that irradiation, with a combination of low water activity and low temperature, results in microbiologically safe kwamegi.

Antioxidant power, lipid oxidation, color, and viability of Listeria monocytogenes in beef bologna treated with gamma radiation and containing various levels of glucose

Ionizing radiation can be used to pasteurize ready-to-eat (RTE) meat products. Thermal processing of RTE meats that contain dextrose results in the production of antioxidants that may interfere with ionizing radiation pasteurization of RTE meat products. Beef bologna was manufactured with dextrose concentrations of 0, 2, 4, 6, and 8%. Antioxidant activity, as measured by the Ferric Reducing Antioxidant Power assay, increased with dextrose concentration but was unaffected by ionizing radiation. Lipid oxidation increased significantly in irradiated bologna (4 kGy) that contained dextrose. Hunter color analysis indicated that the addition of dextrose reduced the ionizing radiation-induced loss of redness (a-value) but promoted the loss of brightness (L-value). The radiation resistance, D10-value, of Listeria monocytogenes that was surface-inoculated onto bologna slices was not affected by dextrose concentration. L. monocytogenes strains isolated from RTE meats after listeriosis outbreaks were utilized. Increased antioxidant activity generated by thermal processing of dextrose in fine emulsion sausages does not present a barrier to radiation pasteurization of RTE meats. However, a high dextrose concentration in combination with gamma irradiation increases lipid oxidation significantly.

Shelf-stable and safe intermediate-moisture meat products using hurdle technology

A number of ready-to-use shelf-stable intermediate-moisture (IM) spiced mutton and spiced chicken products were developed with a combination of hurdles (reduced moisture, vacuum packing, and irradiation). The water activity of the products was reduced to about 0.80 either by grilling or by hot-air drying. These IM products were vacuum packed and subjected to gamma radiation processing at 0 to 10 kGy. Microbiological analyses revealed a radiation dose-dependent reduction in total viable counts and in numbers of Staphylococcus species. IM meat products that did not undergo radiation treatment showed visible mold growth within 2 months. The products subjected to irradiation at 10 kGy showed an absence of viable microorganisms and also retained high sensory acceptability for up to 9 months at ambient temperatures.

Combined effect of antimicrobial coating and gamma irradiation on shelf life extension of pre-cooked shrimp (Penaeus spp.)

The present study was conducted to evaluate the combined effect of low-dose gamma irradiation and antimicrobial coating on the shelf life of pre-cooked shrimp (Penaeus spp.). Antimicrobial coatings were obtained by incorporating various concentrations of thyme oil and trans-cinnamaldehyde in coating formulations prepared from soy or whey protein isolates. Coated shrimps were stored at 4 +/- 1 degrees C under aerobic conditions and were periodically evaluated for aerobic plate counts (APCs) and Pseudomonas putida. Sensory evaluations were performed for appearance, odor, and taste using a hedonic test. Results showed that gamma irradiation and coating treatments had synergistic effects (p < or = 0.05) in reducing the APCs and P. putida with at least a 12-day extension of shelf life. Without irradiation, the inhibitory effects of the coating solutions were closely related to the concentration of thyme oil and trans-cinnamaldehyde. No detrimental effects of gamma irradiation on organoleptic parameters (appearance, odor, and taste) were observed. However, incorporation of thyme oil and trans-cinnamaldehyde reduced the acceptability scores for taste and odor.

Reduction of normal flora by irradiation and its effect on the ability of Listeria monocytogenes to multiply on ground turkey stored at 7 degrees C when packaged under a modified atmosphere

Listeria monocytogenes did not multiply faster during storage at 7 degrees C on irradiated than on nonirradiated raw ground turkey, and there was a concentration-dependent inhibition of its multiplication by CO2. Ground turkey was gamma irradiated at 5 degrees C to 0, 1.5, and 2.5 kGy and inoculated (approximately 100 CFU/g) after irradiation with a cocktail of L. monocytogenes ATCC 7644, 15313, 49594, and 43256. The meat was then packaged in air-permeable pouches or under atmospheres containing 30 or 53% CO2, 19% O2, and 51 or 24% N2 and stored at 7 degrees C for up to 28 days. A dose of 2.5 kGy extended the time for the total plate count (TPC) to reach 10(7) CFU/g from 4 to 19 days compared to that for nonirradiated turkey in air-permeable pouches. Following a dose of 2.5 kGy at the end of the 28-day study, the TPCs were 10(6.42) and 10(4.98) under 25% and 50% CO2 atmospheres, respectively. Under air, 30% CO2, and 53% CO2 atmospheres, the populations of L. monocytogenes after 19 days incubation were 10(4.89), 10(3.60), and 10(2.67) CFU/g. The populations of lactic acid bacteria and anaerobic or facultative bacteria were also reduced by irradiation. Irradiating ground turkey did not decrease its safety when it was contaminated following processing with L. monocytogenes.