Wojciech Radzki

Study on vitamin D2 stability in dried mushrooms during drying and storage

The main objective of this work was to determine the stability of vitamin D2 in dried mushrooms Agaricus bisporus, Pleurotus ostreatus and Lentinula edodes during storage, as well as to examine the possibility of inducing vitamin D2 production in dried mushrooms by UVB irradiation. After 1.5 year storage of dried mushrooms, the level of vitamin D2 in button mushrooms was found to be 6.90 μg/g dw, which is a 48.32% of initial level of vitamin D2. In the case of dried oyster and shiitake mushrooms there was a decrease to the level of 66.90% and 68.40%, respectively. It was determined that dried mushrooms can produce ergocalciferol under UVB irradiation. The highest content of vitamin D2 was observed in A. bisporus. Freeze-dried A. bisporus contained from 42.08 to 119.21 μg/g dw and hot-air dried mushrooms contained from 21.51 to 81.17 μg/g dw vitamin D2.

Antioxidant activities and polyphenolics content of Flammulina velutipes mushroom extracts

Abstract A study was conducted in order to determine the content of phenolic compounds and antioxidative activity of extracts from Flammulina velutipes. Water and ethanolic, methanolic, acetone (70% v/v) extracts were prepared from lyophilized fruiting bodies of mushrooms. Different extraction techniques were used: ultrasonication and stirring by a rotary shaker at ambient temperature and at 50oC, and at boiling point for each solvent. Next, total phenolics by Folin-Ciocalteu method, antioxidant capacity (EC) by ferric reducing antioxidant power assay (FRAP) and scavenging ability on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals were analysed in these extracts. It was observed that the extraction method and the kind of solvent influenced the antioxidant activity and concentration of total phenolics in the extracts. The highest concentration of phenolic compounds (7.58±0.17 mg GAE/g extract) were observed for water extract prepared with use of ultrasonification method (at 50oC for 1h). Results showed that water extracts possessed high equivalent capacity (EC) for all applied extraction methods. The highest EC value (9.2±0.18 mM Fe2+/g extract) was observed in water extract prepared by stirring at ambient temperature for 1 h. This extract was characterized by high level of total phenolics. The acetone extracts, prepared by ultrasonic extraction at 50oC for 1 h, at 10 mg/ml showed the highest scavenging activity (57.53±1.18%), although, the value was lower than that of ascorbic acid at 10 mg/ml (60.50±1.32%) Streszczenie Praca miała na celu określenie ogólnej zawartości związków polifenolowych i właściwości przeciwutleniających ekstraktów z grzyba Flammulina velutipes. Z liofilizowanych owocników F. velutipes przygotowano ekstrakty wodne, etanolowe (70% v/v), metanolowe (70% v/v) i acetonowe (70% v/v). Zastosowano różne techniki ekstrakcji: wytrząsanie i ekstrakcję przy użyciu łaźni ultradźwiękowej w temperaturze pokojowej i w 50oC oraz ekstrakcję we wrzącym rozpuszczalniku. W otrzymanych ekstraktach zbadano ogólną zawartość związków polifenolowych metodą Folin-Ciocalteu i ich właściwości przeciwutleniające (EC - equivalent capacity) metodą FRAP (ferric reducing antioxidant power assay) oraz zdolność do neutralizacji wolnych rodników z użyciem DPPH (1,1-diphenyl-2-picrylhydrazyl). Zaobserwowano, że takie czynniki jak warunki ekstrakcji czy rodzaj użytego rozpuszczalnika mają wpływ na właściwości przeciwutleniające i ogólną zawartość związków polifenolowych w otrzymanych ekstraktach. Najwyższą ilość związków polifenolowych uzyskano w wodnych ekstraktach otrzymanych z użyciem łaźni ultradźwiękowej w 50oC (7,58±0,17 mg GAE/g ekstraktu). Wyniki pokazują, że wodne ekstrakty, otrzymane wszystkimi zastosowanymi metodami ekstrakcji, posiadają wysokie właściwości przeciwutleniające. Najwyższą wartość EC (9.2±0.18 mM Fe2+/g ekstraktu) zaobserwowano dla wodnych ekstraktów przygotowanych w pokojowej temperaturze z użyciem wytrząsarki. Te ekstrakty charakteryzowały się również wysoką zawartością związków polifenolowych. Ekstrakty acetonowe otrzymane poprzez zastosowanie łaźni ultradźwiękowej w 50oC przy stężeniu 10 mg/ml wykazywały najwyższą zdolność do redukcji wolego rodnika DPPH (57,53±1,18%) ale niższą niż kwas askorbinowy przy takim samym stężeniu (60,50±1,32%)

Vitamin D 2 Stability During the Refrigerated Storage of Ultraviolet B−Treated Cultivated Culinary-Medicinal Mushrooms

The effects of ultraviolet B (UVB) irradiation on the synthesis of vitamin D2 and its stability during refrigerated storage was determined in fresh cultivated culinary-medicinal mushrooms (Agaricus bisporus, Pleurotus ostreatus, and Lentinus edodes) after harvest. The irradiated mushrooms were stored at 4°C for up to 10 days. The concentrations of vitamin D2 and ergosterol were determined using ultrahigh-performance liquid chromatography/tandem mass spectrometry. The cultivated mushrooms not treated with UVB were devoid of vitamin D2. After UVB irradiation, we obtained mushrooms with a large amount of ergocalciferol. A. bisporus showed the lowest vitamin D2 content (3.55 ± 0.11 μg D2/g dry weight); P. ostreatus contained 58.96 ± 1.15 μg D2/g dry weight, and L. edodes contained 29.46 ± 2.21 μg/g dry weight. During storage at 4°C, the amount of vitamin D2 was gradually decreased in P. ostreatus and L. edodes, whereas in A. bisporus vitamin D2 gradually increased until the sixth day, then decreased. Mushrooms exposed to UVB radiation contain a significant amount of vitamin D2 and are therefore an excellent food source of vitamin D.

Antioxidative properties of milk protein preparations fermented by Polish strains of Lactobacillus helveticus

BACKGROUND The increasing significance of food products containing substances with antioxidative activi- ties is currently being observed. This is mainly due to the fact that pathogenic changes underlying some diseases are related to the carcinogenic effects of free radicals. Antioxidative compounds play an important role in supporting and enhancing the body’s defense mechanisms, which is useful in preventing some civili- zation diseases. Unfortunately, it has been already proved that some synthetic antioxidants pose a potential risk in vivo. Therefore, antioxidant compounds derived from a natural source are extremely valuable. Milk is a source of biologically active precursors, which when enclosed in structural protein sequences are inactive. The hydrolysis process, involving bacterial proteolytic enzymes, might release biopeptides that act in various ways, including having antioxidant properties. The objective of this study was to determine the antioxidant properties of milk protein preparations fermented by Polish strains of L. helveticus. The research also focused on evaluating the dynamics of milk acidification by these strains and analyzing the textural properties of the skim milk fermented products obtained. METHODS The research studied Polish strains of L. helveticus: B734, 141, T80 and T105, which have not yet been used industrially. The antioxidant properties of 1% (w/v) solutions of milk protein preparations (skim milk powder, caseinoglycomacropeptide and α-lactoalbumin) fermented by these strains were determined by neutralizing the free radicals with 2,2-diphenyl-1-picrylhydrazyl (DPPH˙). Moreover, solutions of skim milk powder (SMP) fermented by the microorganisms being tested were analyzed on gel electrophoresis (SDS-PAGE). The dynamics of milk acidification by these microorganisms was also analyzed L. helveticus strains were used to prepare fermented regenerated skim milk products that were subjected to texture profile analysis (TPA) performed using a TA-XT2i (Stable Micro Systems, Godalming, UK). RESULTS The results suggest that the antioxidant activity of fermented milk protein preparations depended on the type of milk protein preparation and was also related to the strain that conducted the fermentation process. The process of caseinoglycomacropeptide (CGMP) fermentation by DSMZ 20075, T105 and 141 signifi- cantly (p < 0.05) influenced the increase in the antioxidant activities of the protein preparation, the highest values of parameter were obtained in samples fermented by L. helveticus T105 (64.82 ±0.013%), while in the case of α-lactoalbumin (α-la), the strongest free radical scavenging activity (66.67 ±0.020%) was noted for unfermented samples (control). CONCLUSIONS The greatest increase in DPPH scavenging activity (% of inhibition) was noted for fermented SMP solutions. The highest values of the parameter measured were recorded for SMP fermented by the reference strain (85.98 ±0.009%) and T80 (81.66 ±0.013%). Strain T105 demonstrated the most desirable properties with respect to milk acidifying dynamic and texture properties of fermented skim milk products, while the reference strain (L. helveticus DSMZ 20075) and L. helveticus T80 seem to be more desirable in terms of the possibility of obtaining fermented protein preparations with the best antioxidant properties. The Polish strains analyzed here might find application in dairy products and also in developing functional food products. Furthermore, the preparations of milk protein that were fermented by the strains being tested may be a natural source dietary antioxidants.

Evaluation of the potential use of probiotic strain Lactobacillus plantarum 299v in lactic fermentation of button mushroom fruiting bodies

BACKGROUND The available literature does not provide data on the application of probiotic strains in mushroom processing. The aim of the study was to evaluate the potential to use the L. plantarum 299v strain with documented probiotic properties in the process of lactic fermentation of button mushroom fruiting bodies (Agaricus bisporus). METHODS Fresh button mushroom fruiting bodies and cultures of lactic acid bacteria L. plantarum Ib and a probiotic strain L. plantarum 299v were the material analysed. Sensory evaluation was performed with a 5-point scale, an instrumental method of colour measurement based on the CIA L*a*b* scale, total phenolic compounds were determined with the Folin method, antioxidant properties were assayed with the DPPH radical test, and reducing power was determined using the FRAP method. RESULTS After a week-long lactic fermentation, the pH value in the samples declined to a level of 3.6 (L. plantarum Ib) and 3.75 (L. plantarum 299v); these values persisted or decreased slightly during the period of maturation of the fermented samples under refrigeration. Fermented mushrooms were assigned high grades in the organoleptic evaluation. The colour analysis revealed significant changes in the values of the L*a*b* parameters in the fermented product, in comparison with fresh mushrooms. Blanching contributed to a significant decrease in the content of total phenolic compounds in the mushroom fruiting bodies and to a decline in antioxidant activity. Mushrooms fermented with the probiotic strain were characterised by higher phenolic compound content and higher antioxidant activity. CONCLUSIONS L. plantarum 299v strain with documented probiotic properties can be applied in fermentation of button mushroom fruiting bodies. Products obtained with the use of both strains were characterised by good sensory properties. The type of strain used in the lactic fermentation of mushroom fruiting bodies had an effect on the phenolic compound content and antioxidant properties of the final product.

THE EFFECT OF ADDITION OF SELECTED MILK PROTEIN PREPARATIONS ON THE GROWTH OF LACTOBACILLUS ACIDOPHILUS AND PHYSICOCHEMICAL PROPERTIES OF FERMENTED MILK

BACKGROUND The intake of fermented milk products, especially yoghurts, has been systematically increasing for a few decades. The purpose of this work was to obtain milk products fermented with a mix of bacterial cultures (yoghurt bacteria and Lactobacillus acidophillus LA-5) and enriched with selected milk protein preparations. Secondly, the aim of the work was to determine physiochemical and rheological properties of the obtained products. METHODS The following additives were applied in the experiment: whey protein concentrate (WPC 65), whey protein isolate (WPI), demineralised whey powder (SPD), caseinoglycomacropeptide (CGMP), α-lactalbumin (α-la), sodium caseinate (KNa) and calcium caseinate (KCa). Milk was fermented using probiotic strain Lactobacillus acidophillus LA-5 and a typical yoghurt culture. The products were analysed in terms of the survivability of bacterial cells during refrigerated storage, rheological properties and syneresis. Fermented milk products were obtained using blends of bacterial strains: ST-B01:Lb-12 (1:1), ST-B01:Lb-12:LA-5 (1:1:2). RESULTS Milk beverages fermented with typical yoghurt bacteria and LA-5 strain showed intensive syneresis. The addition of LA-5 strain caused formation of harder acid gels, comparing to typical yoghurts. Milk products which were prepared from skimmed milk possessed higher values of hardness and consistency coefficient. The increase of concentrations of milk preparations (except of WPI) did not cause significant differences in the hardness of acidic gels obtained by fermentation of mixed culture with a probiotic strain. CONCLUSIONS The applied preparations improved physiochemical properties of the milk beverages which were prepared with a probiotic strain. The increase of protein milk preparations concentration resulted in a gradual decrease of the secreted whey. Among the products that were made of full milk powder and were subjected to three weeks of refrigerated storage the highest survivability of Lb. acidophilus LA-5 was noticed in the samples fortified with 1% WPC.