THE EFFECT OF POLYPHENOLS ON MARKERS OF OXIDATIVE DAMAGE AND DMBA-INDUCED CARCINOGENESIS IN RATS

The correlation between diets supplemented with resveratrol, genistein or quercetin on oxidative damage to proteins, lipids and nucleic acids was examined. Moreover, the rate of formation of changes resulting from carcinogenesis induced by 7,8-dimethylbenz[a]anthracene (DMBA) was assessed. The results for the impact of selected polyphenolic compounds on the intensity of DMBA-induced carcinogenesis were also presented. The polyphenols used, namely resveratrol, genistein and quercetin measured by the concentration of selected biomarkers related to their antioxidant properties and the impact of DMBA and fatty acids in rapeseed oil as well as of progression stage of the cancer process, were also significant.

PRACTICAL APPLICATIONS

The estimation of the impact of selected polyphenolic compounds on the intensity of 7,8-dimethylbenz[a]anthracene-induced carcinogenesis and oxidative damage to proteins, lipids and nucleic acids in rats was examined. Identifying the results of polyphenol activity in selected doses and different suspensions may allow application of these dietary compounds in human cancer prevention or for improvement of pharmacological treatment.     

EFFECT OF VARIOUS ANTIOXIDANTS ON THE OXIDATIVE STABILITY OF ACID AND ALKALI SOLUBILIZED MUSCLE PROTEIN ISOLATES

Protein isolates prepared from cod ( Gadus morhua ) myofibrillar proteins using acid or alkali solubilization are susceptible to oxidative rancidity. Oxidation could be delayed by the exogenous addition of antioxidants. The objective of this research was to compare the efficacy of antioxidants such as δ-tocopherol, butylated hydroxyanisole (BHA) and propyl gallate, to inhibit oxidation in acid- and alkali- solubilized cod protein isolates. Oxidation was catalyzed using cod hemolysate. Oxidation of lipids was monitored by the measurement of thiobarbituric acid reactive substances and painty odor. Results showed that protein isolates prepared using the acid process was significantly ( P <  0.05) more susceptible to lipid oxidation than alkali-solubilized protein isolates. Regardless of pH treatments, the efficacy of various antioxidants decreased in the order propyl gallate  >  BHA  >  δ-tocopherol.

PRACTICAL APPLICATIONS

Research has shown that seafood available for human consumption is rapidly getting depleted and that many fish species may become extinct in the next half-century or so. Acid and alkali solubilization methods are recent but well-known techniques used for preparing protein isolates from under-utilized aquatic species and the by-products of seafood industry. Although numerous researchers have studied the use of acid and alkali processes on several sources of seafood, almost no research has been done on the use of antioxidants to protect protein isolates from lipid oxidation. In our research, we have studied the effect of various antioxidants on the oxidative stability of acid- and alkali-solubilized fish myofibrillar proteins. The results from this work will enable the seafood industry to properly identify the process and the type of antioxidants required for making muscle food products with increased oxidative stability.     

EFFECT OF PROCESSING ON CONSTITUENTS AND OXIDATIVE STABILITY OF MARINE OILS

Changes in the contents of neutral and polar lipids, α-tocopherol, free fatty acids and color of seal blubber oil (SBO) and cod liver oil (CLO) during different processing steps of alkali-refining, bleaching, and deodorization were monitored. Refined, bleached and deodorized (RBD) SBO and CLO contained approximately 39 and 71% less polar lipids than their crude counterparts, respectively. There was also a reduction of 98.5 and 97.4% in the corresponding free fatty acids content of RBD-SBO and RBD-CLO. The content of α-tocopherol in both oils decreased during processing, especially at the bleaching and deodorization steps. The oxidative stability of SBO and CLO following each processing step was determined by measuring peroxide and 2-thiobarbituric acid reactive substances values. Results so obtained indicated that crude oils were most stable while their refined-bleached counterparts were least stable, perhaps due to the removal of endogenous natural antioxidants such as α-tocopherol during processing of oils.     

EFFECT OF CHOCOLATE COATING ON OXIDATIVE STABILITY OF NORMAL AND HIGH OLEIC PEANUTS

Oxidative stability studies were performed on roasted high-oleic acid peanuts (HOP-SunOleic 95) and normal oleic acid peanuts (NOP-Florunner). Peanuts were dry-roasted to a Hunter Lab value of approximately 50. Chocolate-coated peanut bars (6"x4"×1/2") were prepared using milk chocolate, white chocolate, and reduced-fat chocolate (containing salatrim). Chocolate bars were stored at 25C and 0.60 water activity (a_w). Uncoated peanuts were stored at 0.60 and 0.19 a_w at 25C. Samples were removed from storage at 4-week intervals for peroxide value measurement. Oxidation of peanuts with chocolate coatings were higher than the peanuts that were stored uncoated at the same a_w. The peroxide values of NOP were similar for chocolate coated treatments and 0.60 a_w control but the 0.19 a_w control was 2–4 times higher than the others. Chocolate-coated peanuts had higher oxidation rates compared to uncoated peanuts.     

咨询活动效益综合评价模型研究

建立了综合评价指标体系；运用直接和间接量化方法，对难以客观评价的在社会上产生的经济效益和社会效益进行了量化；使用层次分析法，确定了各指标和各分指标的权重；采用区间值抽样调查方法，给出了各指标和各分指标的参考值；利用Ｆｕｚｙ综合评判思想，对评价总得分的计算和咨询机构的定级给出一种较理想的方法．     

丁香提取物对三种果实致腐真菌的抑制作用研究

以丁香等为试材,测定其对3种常见水果致腐真菌的抑制活性.结果表明,丁香乙醇提取物对桔青霉菌、葡萄灰霉菌、苹果褐腐菌均有很好的抑制作用,其抑菌能力在100℃下比较稳定,适宜pH范围较广.     

THE ANTIBACTERIAL EFFECT OF CINNAMALDEHYDE, THYMOL, CARVACROL AND THEIR COMBINATIONS AGAINST THE FOODBORNE PATHOGEN SALMONELLA TYPHIMURIUM

The aim of this study was to investigate the antimicrobial activity of cinnamaldehyde, thymol and carvacrol alone or their combinations against Salmonella Typhimurium. The results showed that the lowest concentrations of cinnamaldehyde, thymol and carvacrol inhibiting the growth of S. Typhimurium significantly were 200, 400 and 400 mg/L, respectively. In a system combining different antimicrobials, treatments with cinnamaldehyde/thymol, cinnamaldehyde/carvacrol and thymol/carvacrol revealed significantly less population of S. Typhimurium and had synergy effect compared with samples treated with cinnamaldehyde, thymol or carvacrol alone. By means of their paired combinations, the lowest addition of cinnamaldehyde, thymol and carvacrol could be decreased from 200, 400 and 400 mg/L to 100, 100 and 100 mg/L, respectively.     

EFFECT OF SPICES ON CAMPYLOBACTER jejuni AT THREE TEMPERATURES

A study was conducted on the effects of oregano, sage and ground cloves on the growth of Campylobacter jejuni. Each spice was added individually to a liquid growth medium at levels of 0.1–1%. C. jejuni was added to the spice-broth mixture and incubated at 4°C, 25°C or 42°C. Colony forming units were determined at 0, 2, 4, 8, 16, 24 and 48 h. At 42°C and a level of 0.5% spice, cloves inhibited the growth of this organism at 16h. However, in the presence of either oregano or sage, an apparent reduction in colony forming units was noted. The presence of sage caused a greater reduction in colony forming units than did oregano. However, incubation beyond 16 h at 42°C, cell growth was noted in all three spice-broth mixtures. In the presence of either sage or oregano, a > 3-log decrease in colony forming units of C. jeiuni was observed when the spice-broth mixture was incubated at 25°C.A < 1-log reduction in colony forming units of C. jejuni in the presence of any of the three spices was revealed at 4°C.     

EFFECT OF FREEZE DAMAGE ON SOYBEAN QUALITY AND STORAGE STABILITY

In order to study the whole bean quality and storage stability of free-zedamaged soybeans, immature soybeans were frozen in their pods at -5.5°C for 6 hr. When compared to undamaged soybeans, freeze-damaged soybeans were found to have similar oil and protein contents and trypsin inhibitor activities, but lower lipoxygenase activity and greener oil color. The oil from freeze-damaged soybeans averaged 0.26% free fatty acid and increased to 1.63% during 14 months of whole bean storage; oil from undamaged soybeans averaged only 0.14% and increased to 0.48% during storage. Sensory evaluation of cooked soybeans showed that freeze damage increased off-flavors and resulted in poorer color.     

APPLICATION OF THE OXIDATIVE STABILITY INDEX FOR ASSESSING THE ANTIOXIDANT PROPERTIES OF FLAVONOIDS1

The antioxidant activities of representative flavonoid classes (flavonols, flavones, flavanones, isoflavones and flavanols) relative to dl‐α‐tocopherol were evaluated using the Oxidative Stability Index (OSI) value. At 5 mM concentrations in tocopherol stripped corn oil (TSCO), antioxidant activity was determined as follows: (+) catechin > quercetin > (+,?) taxifolin > dl‐α‐tocopherol > THI (3′, 4′, 7‐trihydroxyisoflavone) > luteolin. Intra‐assay and inter‐assay coefficients of variation were 1.43% and 2.73%. Peroxide Induction (PI) values were utilizéd as a comparison method using compounds and conditions identical to those in OSI experiments. Relative values for OSI and PI of the flavonoids tested showed a 0.98 correlation. This method also revealed differences in antioxidant activity of catechins due to stereochemistry. The OSI offers a simple, reproducible method for the evaluation of flavonoid antioxidant activities in a lipid environment.