ACTA Scientiarum Polonorum - Technologia Alimentaria News en (c) Wydawnictwo Uniwersytetu przyrodniczego w Poznaniu Role of peroxidation and heme catalysis in coloration of raw meat

It is known, that lipid peroxidation is one of the main factors limiting the ąuality and acceptability of meat and other animal tissues. The current data conceming connection of heme and peroxidation were summarized and analysed here. The muscle food compounds that are most influenced by oxidative processes include unsaturated fatty acids of lipids, amino acids of proteins and heme groups of pigments. Heme proteins and particularly myoglobin are abundant in muscle tissues. Meat colour is primarily influenced by the concentration and chemical State of heme pigments, myoglobin and hemoglobin. Oxygenated myoglobin oxidized to the brown metmyoglobin form and its accumulation is highly correlated with progress of lipid peroxidation. Heme proteins such as hemoglobin or myoglobin accelerate the decomposition of hydroperoxides to free radicals. Metmyoglobin possesses «pseudoperoxidase» activity and catalyzes the oxidation of various compounds following the reaction with hydrogen peroxide. The reaction between hydrogen peroxide and metmyoglobin results in the formation of two active hypervalent myoglobin species, perferrylmyoglobin (*MbFelv=0) and ferrylmyoglobin (MbFelv=0), which participate in lipid oxidation catalysis. Both MbFeIV=0 and *MbFelv=0 are deactivated in the presence of reducing agents, whose naturę determines the overall effect of the pseudoperoxidase cycle. Hypothesis can be put forward that loss of cellular antioxidants might precede the rise of peroxidase-like activity, thus being a sign of incipient discoloration of meats and muscle components of foods.


Drying method effects on the antioxidant activity of quince (Cydonia oblonga Miller) tea

Background. Quince has many health benefits. Dried quince has been used as a tea for centuries. The aim of this study was to investigate the influences of two drying methods on the antioxidant activity of the quince.
Materiał and methods. Fifty two fresh Iranian ąuinces (Cydonia oblonga) were obtained from different parts of Shiraz. Half of the ąuinces were peeled and both peel and flesh immediately frozen at -20°C individually. The remainder was divided in two groups, and dried with sun and oven drying methods. Proximate analysis, caloric, minerał and vitamin C contents were determined in the fresh ąuinces. The total phenolic, DPPH radical scavenging activity and reducing power analysis were done on flesh, peel, sun-dried and ovendried ąuinces.
Results. The proximate and nutritional composition of the fresh ąuinces was similar to those reported by other researchers. Oven-dried and ąuince peel contained higher amounts of phenolics than the sun-dried and flesh ąuinces, respectively. Sun-dried and flesh samples showed lower radical scavenging effect and reducing antioxidant capacity than oven-dried and ąuince peel, respectively.
Conclusion. Overall, oven drying can better preserve the antioxidative activity of the ąuince.

Effect of ethanolic fl ax (Linum usitatissimum L.) extracts on lipid oxidation and changes in nutritive value of frozen-stored meat products

Background. Flaxseed (Linum usitatissimum L.) is an important source of phenolic compounds, mainly lignans. Antioxidant capacities of flaxseed extracts that contain the compounds have been reported earlier. However, there is a lack of accessible information about their activity against lipid oxidation in meat products. Therefore, the effect of ethanolic flaxseed extracts (EFEs) on lipid stability and changes in nutritive value of frozen-stored meat products (pork meatballs and burgers) was determined.
Material and methods. EFEs from three Polish flax varieties (Szafir, Oliwin, Jantarol) were applied in the study. During 150-day storage of meat products, the lipid oxidation (peroxide and TBARS value) and thiamine retention were periodically monitored, alongside with methionine and lysine availability and protein digestibility.
Results. The addition of EFEs significantly limited lipid oxidation in stored meatballs and burgers. EFE from brown seeds of Szafir var. was superior to the others from golden seeds of Jantarol and Oliwin. Moreover, the extracts reduced changes in thiamine and available lysine content, as well as protein digestibility, during storage time. The effect of EFE addition on available methionine retention was limited.
Conclusion. The ethanolic flaxseed extracts exhibit antioxidant activity during frozen storage of meat products. They can be utilized to prolong shelf-life of the products by protecting them against lipid oxidation and deterioration of their nutritional quality. However, antioxidant efficiency of the extracts seems to depend on chemical composition of raw material (flax variety). Further investigations should be carried on to explain the issue.


Optimization of extraction conditions of some polyphenolic compounds from parsley leaves (Petroselinum crispum)

Background. Parsley leaf is a rich source of natural antioxidants, which serve a lot of functions in human body and prevent food from oxidation processes. The aim of the study was to investigate the influence of different extraction solvents and times of extraction on natural antioxidants content. Owing to the knowledge of the properties of extracted components and solvents, as well as their interactions, it is possible to achieve a high effectiveness of active compounds recovery.
Material and methods.
Three different extraction solvents (acetone 70% in water, methanol 80% in water and distilled water) and different times of extraction (30 and 60 minutes) were used to determine the efficiency of extraction of polyphenols and catechins, antioxidant activity against free radicals DPPH and ABTS and the ability to chelate ion Fe2+ in dried parsley leaves. Other natural antioxidants contents in parsley leaves were also determined.
Results and discussion.
In this study the best extraction solvent for polyphenols was acetone 70% and for catechins was distilled water. All extracts examined displayed the antioxidative activity, but water was the best solvent in the method of assaying the activity against ABTS'+ and Fe2+ions chelating capability, whereas methanol turned out to be the least effective in this respect. Opposite results were observed in the case of determining the activity against DPPH*. The prolongation of the extraction time enhanced or decreased antiradical activity in some cases. Additionally, important biologically active compounds in parsley leaves, such as vitamin C (248.31 mg/100 g dry matter), carotenoids (31.28 mg/100 g dry matter), chlorophyll (0.185 mg/g dry matter) were also analysed.

Optimized microwave-assisted extraction of 6-gingerol from Zingiber officinale Roscoeand evaluation of antioxidant activity in vitro

Background. 6-Gingerol is one of the most pharmacologically active and abundant components in ginger, which has a wide array of biochemical and pharmacologic activities. In recent years, the application of microwave-assisted extraction (MAE) for obtaining bioactive compounds from plant materials has shown tremendous research interest and potential. In this study, an efficient microwave-assisted extraction (MAE) technique was developed to extract 6-gingerol from ginger. The extraction efficiency of MAE was also compared with conventional extraction techniques.
Material and methods. Fresh gingers (Zingiber officinale Rose.) were harvested at commercial maturity (originally from Shandong, laiwu, China). In single-factor experiments for the recovery of 6-gingerol, proper ranges of ratio of liquid to solid, ethanol proportion, microwave power, extraction time were determined. Based on the values obtained in single-factor experiments, a Box-Behnken design (BBD) was applied to determine the best combination of extraction variables on the yield of 6-gingerol.
Results. The optimum extraction conditions were as follows: microwave power 528 W, ratio of liquid to solid 26 mL g1, extraction time 31s and ethanol proportion 78%. Furthermore, more 6-gingerol and total polyphenols contents were extracted by MAE than conventional methods including Maceration (MAC), Stirring Extraction (SE), Heat reflux extraction (HRE), Ultrasound-assisted extraction (UAE), as well as the antioxidant capacity.
Conclusion. Microwave-assisted extraction showed obvious advantages in terms of high extraction efficiency and antioxidant activity of extract within shortest extraction time. Scanning electron microscopy (SEM) images of ginger powder materials after different extractions were obtained to provide visual evidence of the disruption effect. To our best knowledge, this is the first report about usage of MAE of 6-gingerol extraction from ginger, which could be referenced for the extraction of other active compounds from herbal plants.


Biochemical and nutritional components of selected honey samples

Background. The purpose of this study was to investigate the relationship of biochemical (enzymes) and nutritional components in the selected honey samples from Malaysia. The relationship is important to estimate the quality of honey based on the concentration of these nutritious components. Such a study is limited for honey samples from tropical countries with heavy rainfall throughout the year.
A number of six honey samples that commonly consumed by local people were collected for the study. Both the biochemical and nutritional components were analysed by using standard methods from Association of Official Analytical Chemists (AOAC). Individual monosaccharides, disaccharides and 17 amino acids in honey were determined by using liquid chromatographic method.
The results showed that the peroxide activity was positively correlated with moisture content (r = 0.8264), but negatively correlated with carbohydrate content (r = 0.7755) in honey. The chromatographic sugar and free amino acid profiles showed that the honey samples could be clustered based on the type and maturity of honey. Proline explained for 64.9% of the total variance in principle component analysis (PCA).
The correlation between honey components and honey quality has been established for the selected honey samples based on their biochemical and nutritional concentrations. PCA results revealed that the ratio of sucrose to maltose could be used to measure honey maturity, whereas proline was the marker compound used to distinguish honey either as floral or honeydew.

Proteomic analysis of albumin and globulin fractions of pea (Pisum sativum L.) seeds

Background. Proteomic analysis is emerging as a highly useful tool in food research, including studies of food allergies. Two-dimensional gel electrophoresis involving isoelectric focusing and sodium dodecyl sulfate polyacrylamide gel electrophoresis is the most effective method of separating hundreds or even thousands of proteins. In this study, albumin and globulin tractions of pea seeds cv. Ramrod were subjected to proteomic analysis. Selected potentially alergenic proteins were identified based on their molecular weights and isoelectric points.
Material and methods. Pea seeds (Pisum sativum L.) cv. Ramrod harvested over a period of two years (Plant Breeding Station in Piaski-Szelejewo) were used in the experiment. The isolated albumins, globulins and legumin and vicilin fractions of globulins were separated by two-dimensional gel electrophoresis. Proteomic images were analysed in the ImageMaster 2D Platinum program with the use of algorithms from the Melanie application. The relative content, isoelectric points and molecular weights were computed for
all identified proteins. Electrophoregrams were analysed by matching spot positions from three independent replications.

Results. The proteomes of albumins, globulins and legumin and vicilin fractions of globulins produced up to several hundred spots (proteins). Spots most characteristic of a given fraction were identified by computer analysis and spot matching. The albumin proteome accumulated spots of relatively high intensity over a broad range of pi values of -4.2-8.1 in 3 molecular weight (MW) ranges: I - high molecular-weight albumins with MW of -50-110 kDa, II - average molecular-weight albumins with MW of -20-35 kDa, and III - low molecular-weight albumins with MW of -13-17 kDa. 2D gel electrophoregrams revealed the presence of 81 characteristic spots, including 24 characteristic of legumin and 14 - of vicilin.
Conclusions. Two-dimensional gel electrophoresis proved to be a useful tool for identifying pea proteins. Patterns of spots with similar isoelectric points and different molecular weights or spots with different isoelectric points and similar molecular weights play an important role in proteome analysis. The regions characteristic of albumin, globulin and legumin and vicilin fractions of globulin with typical MW and pi values were identified as the results of performed 2D electrophoretic separations of pea proteins. 2D gel electrophoresis of albumins and the vicilin fraction of globulins revealed the presence of 4 and 2 spots, respectively, representing potentially allergenic proteins. They probably corresponded to vicilin fragments synthesized during post-translational modification of the analysed protein.

Health effects of dietary fi ber

Dietary fi bre is a group of food components which is resistant to digestive enzymes and found mainly in cereals, fruits and vegetables. Dietary fi ber and whole grains contain a unique blend of bioactive components including resistant starches, vitamins, minerals, phytochemicals and antioxidants. Dietary fi ber which indigestible in human small intestinal, on the other hand digested completely or partially fermented in the large intestine, is examined in two groups: water-soluble and water insoluble organic compounds. Dietary fi ber can be separated into many different fractions. These fractions include arabinoxylan, inulin, pectin, bran, cellulose, β;-glucan and resistant starch. Dietary fi bres compose the major component of products with low energy value that have had an increasing importance in recent years. Dietary fi bres also have technological and functional properties that can be used in the formulation of foods, as well as numerous benefi cial effects on human health. Dietary fi bre components organise functions of large intestine and have important physiological effects on glucose, lipid metabolism and mineral bioavailability. Today, dietary fi bers are known to be protective effect against certain gastrointestinal diseases, constipation, hemorrhoids, colon cancer, gastroesophageal refl ux disease, duodenal ulcer, diverticulitis, obesity, diabetes, stroke, hypertension and cardiovascular diseases. In this review the physicochemical and biological properties of dietary fi bers and their important implications on human health will be investigated.

Effects of physical activity during pregnancy and gestational weight gain on newborn weight and length at birth in Warmińsko-Mazurskie province

Background. Epidemiological research has identifi ed a relationship between maternal physical activity, early nutrition and infant birth weight with likelihood of developing future diseases. The aim of the study was to determine a relationship between gestational weight gain and physical activity during pregnancy to the nutritional status of newborns.
Material and methods. The presented study was conducted in the period from February 2010 until November 2012 in the gynecological and obstetric clinics in Warmińsko-Mazurskie voivodeship with various levels of reference. The research subjects included 510 women in the puerperal period aged 18-36. The scope of the research included an assessment of the selected anthropometric parameters of both pregnant women (body mass, height, BMI, gestational weight gain) and newborns (infant birth weight, infant length, Ponderal Index), as well as an analysis of the connections between the gestational weight gain, physical activity during pregnancy and anthropometric parameters of newborns.
Results and conclusions. In the study group there was a signifi cant percentage of women characterised by an inactive lifestyle and excessive gestational weight gain. There were signifi cantly higher neonatal birth anthropometric parameters in women with abnormal excessive gestational weight gain than in women with normal and inappropriate – low gestational weight gain. The highest percentage of women with appropriate weight gain was observed in the group of women who are physically active, although this requires confi rmation in larger population. Our studies have not shown statistically signifi cant differences between the gestational weight gain and nutritional status of newborns in relation to the level of physical activity of pregnant women.

Assessment of the risk of exposure to cadmium and lead as a result of the consumption of low-fat dairy products by expectant and lactating women

Background. The study aimed to assess the risk related to consumption of low-fat dairy products by expectant and lactating women.
Material and methods. A survey was used to verify the popularity of such products among expectant and lactating women and then the content of Cd and Pb in low-fat dairy products was determined.
Results. In the group of expectant women consuming dairy products, nearly 93% of the respondents consumed low-fat dairy products, while among lactating women the result was 90%. Both the expectant and lactating women mostly preferred milk and fruit yoghurt. It was found that the studied low-fat products did not contain more Cd and Pb than their standard counterparts.
Conclusion. Taking into account the intake of low-fat milk and dairy products declared by respondents, such products must be regarded safe in terms of Cd and Pb content. The maximum supply of Cd and Pb for both groups of women did not exceed 3% TWI and 2% BMDL10.