ACTA Scientiarum Polonorum - Technologia Alimentaria News en (c) Wydawnictwo Uniwersytetu przyrodniczego w Poznaniu Exopolysaccharides from yeast: insight into optimal conditions for biosynthesis, chemical composition and functional properties – review

The yeast exopolysaccharides (EPS) are not a well-established group of metabolites. An industrial scale    of this EPS production is limited mainly by low yield biosynthesis. Until now, enzymes and biosynthesis pathways, as well as the role of regulatory genes, have not been described. Some of yeast EPS show anti- tumor, immunostimulatory and antioxidant activity. Others, absorb heavy metals and can function as bioac- tive components of food. Also, the potential of yeast EPS as thickeners or stabilizers can be found. Optimal conditions for the biosynthesis of yeast exopolysaccharides require strong oxygenation and low temperature of the culture, due to the physiology of the producer strains. The medium should contain sucrose as a carbon source and ammonium sulfate as inorganic nitrogen source, wherein the C:N ratio in the substrate should be 15:1. The cultures are long and the largest accumulation of polymers is observed after 4 or 5 days of culturing. The structure of yeast EPS is complex which affects the strain and culture condition. The EPS from yeast are linear mannans, pullulan, glucooligosaccharides, galactooligosaccharides and other heteropolysaccharides containing α-1,2; α-1,3; α-1,6; β;-1,3; β;-1,4 bonds. Mannose and glucose have the largest participation of carbohydrates forming EPS.

Application of acid whey and set milk to marinate beef with reference to quality parameters and product safety

Background. The aim of the study was to evaluate the potential of acid whey and set milk as a marinade in the traditional production of fermented eye round.
Material and methods. Studies involved assaying pH value, water activity (aw), oxidation-reduction po- tential and TBARS value, colour parameters in CIE system (L*, a*, b*), assaying the number of lactic acid bacteria and certain pathogenic bacteria after ripening process and after 60-day storing in cold storage. Sen- sory analysis and analysis of the fatty acids profile were performed after completion of the ripening process.
Results. Analysis of pH value in the products revealed that application of acid whey to marinate beef resulted in increased acidity of ripening eye round (5.14). The highest value of the colour parameter a* after ripening process and during storage was observed in sample AW (12.76 and 10.07 respectively), the lowest on the other hand was observed in sample SM (10.06 and 7.88 respectively). The content of polyunsaturated fatty acids (PUFA) was higher in eye round marinated in acid whey by approx. 4% in comparison to other samples.
Conclusion. Application of acid whey to marinade beef resulted in increased share of red colour in gen-  eral colour tone as well as increased oxidative stability of the product during storage. It also increased the content of polyunsaturated fatty acids (PUFA) in the product. All model products had high content of lactic acid bacteria and there were no pathogenic bacteria such as: L. monocytogenes, Y. enterocolitica, S. aureus, Clostridium sp.

Variable effect of steam injection level on beef muscles: semitendinosus and biceps femoris cooked in convection-steam oven

Background. Combi ovens are used very often in restaurants to heat up food. According to the producers the equipment allows to cook meat portions which are more tender and flavoursome comparing to conventional cooking techniques.
Materials and methods. Beef steaks from muscles semitendinosus and biceps femoris were cooked in convection-steam oven at three humidity levels: 10, 60 and 100%. Chemical composition, including total and insoluble collagen content and cook losses were analysed along with the texture and colour parameters.
Results. M. biceps femoris was the hardest and the most chewy at 100% steam saturation level and hardness measured for m. semitendinosus was the lowest at 10% of vapour injection. Changing the steam conditions in the oven chamber did not affect the detectable colour differences of m. biceps femoris, but it was significant for m. semitendinosus. Applying 100% steam saturation caused higher cook losses and the increase of insolu- ble collagen fractions in both analysed muscles.
Conclusions. The results are beneficial for caterers using steam-convection ovens in terms of providing evidence that the heating conditions should be applied individually depending on the muscle used. The ten- derness of m. semitendinosus muscle cooked at 10% steam saturation level was comparable to the tender- ness obtained for the same muscle aged for 10 days and cooked with 100% steam saturation. Steaks from m. biceps femoris muscle should be cooked with maximum 60% saturation level to obtain higher tenderness.

Effect of extraction solvents on the biomolecules and antioxidant properties of Scorzonera undulata (Asteraceae): Application of factorial design optimization phenolic extraction

Background. Phenolic compounds were extracted and isolated from S. undulata roots.
Methods. Sample of roots from E. hirta was tested for phenolic compounds, and in vitro antioxidant activity by diphenyl-1-picrylhydrazyl (DPPH) assay, ABTS, FRAP and reducing power was measured using cyano- ferrate method.
Results. The methanolic fraction exhibited the highest total phenol content (6.12 ±0.11 mg AGE/g DW). On the other hand, the highest flavonoids concentration was observed in ethyl acetate fraction (2.90 ±0.05 mg CE/g DW) in addition to anthocyanins (28.56 ±3.96 mg/l). Besides, the highest level of tannins content was measured in the polar aprotic solvent ethyl acetate extract (3.25 ±0.06 mg CE/g DW). The different extracts of S. undulata were evaluated for their radical scavenging activities by means of the DPPH assay. The strongest scavenging activity was observed in methanolic fraction scavenged radicals effectively with IC   values of 0.14 ±0.02 mg/ml. Similarly, the potassium ferricyanide reduction (FRAP) and ABTS•+ of methanol extract. On the other hand, the total reducing power of ethyl acetate extract was found higher than of other extracts. This paper presents the application of the design-of experiment method for optimizing the extraction of phe- nolic content using methanol solvent. The resulting regression model has shown that the effect of temperature is not statistically significant (with >95% certainty), while that of agitation speed is. The two main effects are contributed by the solvent concentration and the maceration period.
Conclusion. Our results clearly showed that the extraction of phenolic compounds and their antioxidant ca- pacity is significantly affected by solvent combinations. S. undulata presented the highest total phenolic con- tent, total flavonoids content and antioxidant capacity values. The resulting regression model has shown that the effect of temperature is not statistically significant (with >95% certainty), while that of agitation speed is.

PCL assay application in superoxide anion-radical scavenging capacity of tea Camellia sinensis extracts

Background. Plant polyphenols are known for their limiting of adverse effects on reactive oxygen species (ROS) in biological systems. The photochemiluminescence (PCL) assay allows to evaluate the antiradical activity of a compound in the presence of a superoxide anion-radical (O •-), which is one of the ROS directly associated with the human body. In this work, determination of the superoxide anion radical scavenging ac- tivity of different tea extracts using the PCL assay was performed.
Material and methods. Investigations were conducted on different tea leaves extracts. The study included five kinds of tea leaves subjected to aqueous and ethanol extraction procedure. Catechins content was evalu- ated using HPLC. Antiradical activity of the samples was conducted with use of Photochem assay.
Results. Analysis of total catechins content in tea aqueous extracts enabled them to be arranged as follows: yellow > green > white > red > black, while for ethanol extracts it was: yellow = green > white > red > black. The examined tea extracts were ranked from highest to lowest water-soluble antioxidative capacity (ACW) values as follows: yellow > green > white > red > black. The results of lipid-soluble antioxidative capacity (ACL) values for aqueous extracts were similar; however, were approximately 50% lower than those pre- sented as ACW. The second examined group were ethanol extracts, which ranked for ACW values: yellow > green = red = white > black, while ACL values ranked as follows: yellow > white = black = red > green. PCL assay results were correlated with total catechin content in aqueous extracts.
Conclusions. Antiradical activity of different tea leaves extracts in PCL assay, showed that the highest activ- ity was found in extracts of yellow tea; the lowest, however, was identified in black tea extracts.

Antioxidant effcacy of unripe banana (Musa acuminata Colla) peel extracts in sunflower oil during accelerated storage

Background. Sunflower oil is prone to oxidation during storage time, leading to production of toxic com- pounds that might affect human health. Synthetic antioxidants are used to prevent lipid oxidation. Spreading interest in the replacement of synthetic food antioxidants by natural ones has fostered research on fruit and vegetables for new antioxidants.
Material and methods. In this study, the efficacy of unripe banana peel extracts (100, 200 and 300 ppm)  in stabilizing sunflower oil was tested under accelerated storage (65°C) for a period of 24 days. BHA and α-tocopherol served as comparative standards besides the control. Established parameters such as peroxide value (PV), iodine value (IV), p-anisidine value (p-AnV), total oxidation value (TOTOX), thiobarbituric acid reactive substances (TBARS) and free fatty acid (FFA) content were used to assess the extent of oil deterioration.
Results. After 24 days storage at 65°C, sunflower oil containing 200 and 300 ppm extract of unripe banana peel showed significantly lower PV and TOTOX compared to BHA and α-tocopherol. TBARS, p-AnV and FFA values of sunflower oil containing 200 and 300 ppm of unripe banana peel extract exhibited comparable inhibitory effects with BHA. Unripe banana peel extract at 200 and 300 ppm demonstrated inhibitory effect against both primary and secondary oxidation up to 24 days under accelerated storage conditions.
Conclusions. Unripe banana peel extract may be used as a potential source of natural antioxidants in the ap- plication of food industry to suppress lipid oxidation.

Antioxidant activity of selected wild Canadian prairie fruits

Background. Canadian prairies are a habitat for unique wild plants. The main object of the present study was to investigate phytochemicals content and antioxidant activity in seven wild Canadian prairie fruits.
Material and methods. The presence of total phenolics, flavonoids, anthocyanins and antioxidant activity were identified in the extracts according to standard procedure.
Results. Wild rose had the highest amounts of total phenolics and total flavonoids, whereas elderberry ex- hibited the highest amount of anthocyanins. All extracts showed good scavenging activities towards DPPH radicals. The results showed a good linear relationship between oxygen radical absorbance capacity and total phenolics indicating that radicals are scavenged at a greater rate as the total phenolics content increases. Addi- tionally, all extracts when applied at concentration of 800 ppm, showed ability to inhibit oxidation of canola oil. In SOT test the best results were obtained when extract of American mountain ash was used. In general, wild rose followed by American mountain ash demonstrated the highest antioxidant activity among assessed Canadian prairie fruits.
Conclusion. From the results it can be concluded that prairie fruit extracts are a rich source of phenolic compounds and poses a high antioxidant activity, confirmed by assessment with different type of radicals employed.

Antioxidant activity of insect gall extracts of Pistacia integerrima

Background. Pistacia integerrima (P. integerrina) insect galls are widely used in ayurveda and siddha sys- tem of medicine as karkatasringi. The use of leaf galls as a rejuvenator may be attributed to antioxidant prop- erty, however there is less scientific evidence. Therefore, the aim of this study was to evaluate the chemical composition and the antioxidant potential of leaf gall extracts (aqueous and ethanol) of P. integerrina, which is extensively used in the preparation of traditional medications.
Material and methods. The antioxidant activities of aqueous and ethanolic leaf gall extracts were examined using diphenylpicrylhydrazyl (DPPH), hydroxyl scavenging and ferric reducing power (FRAP) methods.
Results. The presences of phenolics, tannins, phytosterols, triterpenoids, saponins, flavonoids and reducing sugars were identified in both the extracts. In comparison to the aqueous extract, the ethanolic extract had the highest total phenolic and flavonoid content at 234 ±2.4 mg of GAE/g d.w. and 95.5 ±3.2 mg of QUE/g d.w., respectively. This higher content of total phenolics and flavonoids found in the ethanolic extract was directly associated with higher antioxidant activity.
Conclusion. This study demonstrates the poetnet antioxidant activities of P. integerrima leaf gall extracts. Further, there was a strong association between the higher antioxidant activities with that of higher total phe- nolic and flavonoid content in the ethanolic leaf gall extracts of P. integerrima. The results encourage the use of P. integerrima leaf gall extracts for medicinal health, functional food and nutraceuticals applications, due to their antioxidant properties. Future work will be interesting to learn the chemical composition and better understand the mechanism of action of the antioxidants present in the extract for development as a drug for therapeutic application.


Background. Cereal products constitute the basis of the diet pyramid. While the consumption of such prod- ucts as bread decreases, the group of food which popularity increase is cereal snacks. Unfortunately, the dietary value of this group of foodstuffs is limited. Thus, different types of cereal bran may be added to the produced snacks to enhance their nutritive value. However, an addition of bran may have an adverse effect on quality attributes of products.
Material and methods. Corn grits enriched with 20 and 40% oat, wheat and rye bran was extruded. Basic parameters determining the nutritive value, physical characteristics and sensory attributes of the six produced types of extrudates were measured and compared. Moreover, the effect of additives applied on viscosity of aqueous suspensions of the raw materials and extrudates under controlled conditions was measured using RVA.
Results. The dietary value of snacks containing bran depends on the type and quantitative shares of the additives. The content of dietary fibre in produced extrudates ranged from 6.5 to 15.8%, including soluble dietary fibre at 2.1 to 3.7%. With an increase of bran content in extrudates, their expansion decreased, density increased and the colour of extrudates changed (reduced brightness, increased a*, decreased b*). In sensory evaluation the highest acceptability was given to extrudates with a 20% addition of oat bran, while the lowest was given for those with 40% wheat bran. Based on PCA results positive correlations were found between overall desirability and crispiness, porosity, taste, colour and expansion. Negative correlations between desir- ability and hardness and density of extrudates were observed. The additives and their level also had an effect on changes in viscosity of aqueous suspensions measured using RVA. However, no correlation was found between quality features of extrudates and values of attributes measured in the analysis of viscosity.
Conclusion. In the production of corn extruded snacks an addition of oat, wheat and rye bran may be applied up to 20%. Such products have adequate sensory and dietary quality. The Critical Paste Test (Whalen et al., 1996) is not applicable in the evaluation of suitability of the corn raw material with an addition of oat, wheat and rye bran to produce extrudates.

Estimation of the antioxidant activity of the commercially available fermented milks

Background. Free radicals are connected with the increased risk of certain diseases, especially cancers. There is some scientific evidence that antioxidant-rich diet may inhibit the negative impact of free radicals. The aim of the present study was to analyse the antioxidant capacity of the selected commercial natural and flavoured fermented milks offered in Poland, derived from different producers.
Material and methods. The following commercially available natural fermented milks: 12 yoghurts, 12 kefirs, 2 butter milks, 2 cultured milks, Turkish yoghurt drink (ayran) and the following flavoured fermented milks: 22 yoghurts, 2 acidophillus milks, 2 kefirs, butter milk and vegetable flavoured fermented milk were analysed for their antioxidant potential. The antioxidant capacity was assessed, in two replicates and twice for each product, by means of ferric reducing antioxidant power (FRAP) and DPPH radical scavenging ability (expressed as ARP – anti radical power) methods.
Results. Among all analysed plain products, yoghurts and kefirs were characterised by the highest antioxi- dant activity. The presence of probiotic Lactobacillus casei strains in the product positively affected both FRAP and ARP values. Antioxidant capacity of the flavoured fermented milks was primarily affected by the type and quality (e.g. fruit concentration) of the added flavouring preparation. The most valuable regarding the estimated parameters were chocolate, coffee, grapefruit with green tea extract as well as bilberry, forest fruits, strawberry and cherry with blackcurrant fillings.
Conclusions. Protein content, inclusion of probiotic microflora as well as type and quality of flavouring preparations are the main factors affecting antioxidant properties of fermented milks.

Fermented probiotic beverages based on acid whey

Background. Production of fermented probiotic beverages can be a good method for acid whey usage. The obtained products combine a high nutritional value of whey with health benefits claimed for probiotic bac- teria. The aim of the study was to define quality properties of beverages based on fresh acid whey and milk with addition of buttermilk powder or sweet whey powder.
Material and methods. Samples were inoculated with two strains of commercial probiotic cultures: Lac- tobacillus acidophilus La-5 or Bifidobacterium animalis Bb-12. After fermentation, samples were stored at refrigerated conditions. After 1, 4, 7, 14 and 21 days sensory characteristics, hardness, acetaldehyde content, titratable acidity, pH acidity and count of bacteria cells were evaluated.
Results. Throughout all storage period, the number of bacteria was higher than 8 log cfu/ml in the all sam- ples. Beverages with La-5 strain had higher hardness and acidity, whilst samples with Bb-12 contained more acetaldehyde. Samples with buttermilk powder had better sensory properties than with sweet whey powder.
Conclusions. Obtained products made of acid whey combined with milk and fortified with buttermilk pow- der or sweet whey powder, are good medium for growth and survival of examined probiotic bacteria strains. The level of bacteria was sufficient to provide health benefits to consumers.

Effect of bacteria proportion on the fermentation of goat yoghurt with probiotic culture

Background. Goat milk production in Shaanxi province is dominant in China, but the product is mainly in- fant formula and adult milk powder; product homogeneity is serious and has no goat yoghurt with probiotic culture.
Methods. The effect of bacteria proportion (1:3:1, 1:2:1, 1:1:1, 2:1:1, 3:1:1) on pH, acidity, and viable counts and sensory evaluation of goat milk fermented by probiotics including L. acidophilus, B. bifidum  or L. casei besides, S. thermophilus and L. bulgaricus for developing AB-goat yoghurt and BC-goat yoghurt was investigated.
Results. The optimum bacteria proportion of L. acidophilus : B. bifidum : S. thermophilus and L. bulgaricus for AB-goat yoghurt and B. bifidum : L. casei : S. thermophilus and L. bulgaricus for BC-goat yoghurt were both 2:1:1. The pH, acidity, the viable counts of L. acidophilus and B. bifidum, the total viable counts were respectively 4.60, 7.73 (g/L), 3.50×107 cfu/mL, 3.40×107 cfu/mL and 2.30×109 cfu/mL in AB-goat yoghurt. The pH, acidity, the viable counts of B. bifidum and L. casei, the total viable counts were respectively  4.61, 8.16 (g/L), 7.60×107 cfu/mL, 5.60×107 cfu/mL and 2.04×109 cfu/mL in BC-goat yoghurt.
Conclusion. The bacteria proportion had a significant effect on fermentation of AB- and BC-goat yoghurt, the results are beneficial for developing AB-goat yoghurt and BC-goat yoghurt.