Enzymatic hydrolysis combined with high‐pressure homogenisation for the preparation of polysaccharide‐based nanoparticles from the by‐product of Flammulina velutipes

In this study, protease, α‐amylase and 5‰ β‐glucanase enzymolysis in combination with high‐pressure homogenisation were used for the preparation of polysaccharide‐based nanoparticles from Flammulina velutipes stipes, respectively, named FNP‐1, FNP‐2 and FNP‐3, and the nanoparticles were subsequently characterised. The FNP size distribution ranged from 50 nm to 300 nm, among which FNP‐2 and FNP‐3 were smaller than FNP‐1, based on the SEM images. GC‐MS results showed that these particles were mainly composed of glucose and glucosamine. The FNP dispersions at 1 wt% behaved as non‐Newtonian, shear‐thinning fluids, and the FNP‐3 dispersion presented superior viscoelasticity. With an increasing degree of enzymolysis, the thermal stability of the FNPs decreased. In addition, these particles presented various cation‐exchange properties. Therefore, the Flammulina velutipes polysaccharide‐based nanoparticles obtained from this study can be potentially used as a promising functional food ingredient in the food industry.     

Comparative study on antioxidant activity of four varieties of Flammulina velutipes with different colour

Flammulina velutipes is one of the most popular edible mushrooms consumed all around the world. This study evaluates the antioxidant potential of four varieties of F. velutipes with different colour (snowy white, off‐white, yellow, snuff colour) in terms of DPPH scavenging activity, reducing power, hydroxyl radical scavenging activity and metal chelating activity. The total phenols, phenolic acid and l ‐ergothioneine contents in the four varieties of F. velutipes were also determined. Extracts from yellow F. velutipes demonstrated better antioxidant activities in DPPH, hydroxyl radical and metal chelating activity and extracts from snowy white F. velutipes showed higher activity in reducing power. However, snuff colour F. velutipes exhibited the lowest antioxidant activity in all the tested assays. The antioxidant activities may be attributed to the higher phenolic acid and l ‐ergothioneine contents as a linear relation was observed between the two components and the antioxidant parameters.     

Effects of extraction solvents,cooking procedures and storage conditions on the contents of ergothioneine and phenolic compounds and antioxidative capacity of the cultivated mushroom Flammulina velutipes

Edible mushrooms contain considerable amounts of the potent natural antioxidant 2‐thiol‐l ‐histidine‐betaine (l ‐ergothioneine, ESH). The objective of this study was to evaluate the effects of extraction solvents, common cooking methods and storage conditions on the ESH content, total phenols (TPs) and antioxidant capacity of the edible mushroom Flammulina velutipes fruiting body and its hot water extract that had been stored at different temperatures. Regarding cooking procedures, boiling in water resulted in the highest losses of antioxidant activity of both ESH and TPs. Most of the losses of ESH and TPs were detected in the cooking water. The ESH contents in the raw mushroom fruiting bodies significantly decreased after 8 days of refrigerated storage under both dark and fluorescent lighting conditions. However, the TP content in the raw mushroom stored under fluorescent lighting significantly increased during 10 days of refrigeration. In contrast, the ESH and TP contents as well as DPPH radical scavenging ability of the fruiting bodies remained unchanged for up to 15 days of frozen storage at ?18 °C. The same behaviour was obtained with the mushroom extract packed in plastic tubes. The correlation between DPPH radical scavenging activity and ESH contents was higher than that for TP compounds.     

Value‐added use of mushroom ergothioneine as a colour stabilizer in processed fish meats

BACKGROUND: Ergothioneine (ESH), a potent antioxidant, has been found in certain edible mushrooms. Our previous research showed that ESH extracted from the edible mushroom Flammulina velutipes has a positive effect on the colour stability of beef and tuna meat. The purpose of the present study was to compare the efficacy and applicability of ESH extracts prepared from different mushroom species as a colour stabilizer in fish meats. RESULTS: Levels of ESH higher than 2.8 mg mL^?1 were found in extracts prepared from the fruiting bodies of F. velutipes, Lentinula edodes, Pleurotus cornucopiae and Pleurotus eryngii and the processing waste of F. velutipes. When 1 mL of each of the extracts was added to 100 g of minced bigeye tuna and yellowtail meats, the bright‐red colour remained after 5 and 2 days, respectively, of ice storage. The anti‐discoloration efficacy of 1 mL of the extracts prepared from 10 g of the fresh waste portion of F. velutipes was similar to that of its fruiting body or 0.5 g kg^?1 of sodium ascorbate when added to 100 g of minced bigeye tuna meat under ice storage. CONCLUSION: The results of this study clearly showed that ESH prepared from different mushroom species stabilized the colour of fish meats, and the extract from the F. velutipes was the most effective. Copyright © 2010 Society of Chemical Industry     

Effect of nanocomposite-based packaging on storage stability of mushrooms (Flammulina velutipes)

In this study, a polyethylene (PE) packaging material that contained nano-Ag, nano-TiO₂, nano-SiO₂, and attapulgite was prepared and its effect on storage stability of mushrooms (Flammulina velutipes) was investigated. The results showed that the nanocomposite-based packaging material (Nano-PM) regulated oxygen and carbon dioxide level, eliminated ethylene and inhibited the growth of microbes, which is a benefit on preservation quality of mushrooms, compared to the normal PE material (Normal-PM). After 14 days of storage, mushroom weight loss, mushroom cap opening, stipe elongation and respiration of Nano-PM stored mushroom were significantly (P < 0.05) inhibited. Furthermore, treatment with the Nano-PM improved the retention of vitamin C, soluble protein, and total soluble solids contents of F. velutipes. The results therefore are promising for the preservation of F. velutipes in order to expand its shelf life and improve its preservation quality by use of this Nano-PM.Industrial relevanceFlammulina velutipes, also named as golden needle mushroom, is one of the most popular edible mushrooms worldwide. Its production and consumption ranked the fourth place among all edible mushrooms in the world. However, fresh golden needle mushrooms are highly perishable. Therefore, preserving freshness of the mushrooms is the main objective of postharvest technology. In the present study, we developed a new type of effective and economic nanoparticle packaging materials and applied it to mushroom preservation. A local company (Jiangsu Tianfeng Biological Technology Co., Ltd) producing mushrooms has started to use this nano-preservation technology during the postharvest transportation and sales. In conjunction with the results of present research, we suggests that nano-composite based packaging materials is a good way for preserving fresh mushrooms and has the potential to be commercialized.     

Physicochemical characteristics and gelation properties of collagen superfine powder from swine skin: the effects of preheating treatment

Following different preheating treatments (60 °C for 20 min; 80 °C for 20 min; or 120 °C for 10 min, referred as T₁, T₂ and T₃), edible collagen superfine powder (CSP) from swine skin was prepared by superfine grinding method. The CSPs showed a preheating‐dependent decrease in the D₅₀, with different degrees of hydrolysis (9.51–31.05%). A significant effect of preheating on rheological properties of the CSP aqueous dispersions at pH 4–9 was observed, wherein T₂ had the biggest viscosity and water holding capacity. All the 5% CSP dispersions were transformed into stable cold‐set gels after heating at 50–90 °C for 20 min, with insignificant differences in strength. These attributes were consistent with microstructures of the CSP gels detected by scanning electron microscope.     

Optimization of ultrasonic extraction of Flammulina velutipes polysaccharides and evaluation of its acetylcholinesterase inhibitory activity

Polysaccharide was testified to be the main component of Flammulina velutipes for inhibiting AChE activity in our preliminary study. Therefore, response surface methodology, based on Box-Behnken design, was used to optimize the ultrasonic extraction conditions of F. velutipes polysaccharides (FVP). Four independent variables (ratio of water to raw material, ultrasonic power, ultrasonic time, and ultrasonic temperature) were taken into consideration. A quadratic model, adequate for reasonably predicting the yield of FVP, was constructed between ultrasonic conditions and yield of FVP. A yield of FVP of 8.33% was obtained under a modified condition (ratio of water to material of 25 ml/g, ultrasonic power of 620 W, ultrasonic time of 20 min, and ultrasonic temperature of 45 °C). Subsequently, acetylcholinesterase (AChE) inhibitory activity and 1,1-diphenyl-2-picryl hydrazine (DPPH) scavenging activity of FVP were determined. AChE inhibitory rate of 18.51% and DPPH scavenging rate of 61.24% were obtained at 0.6 mg/ml of FVP, indicating a good potential of FVP to enhance learning and cognitive ability.     

Koji fermentation based on extracellular peptidases of <Emphasis Type="Italic">Flammulina velutipes</Emphasis>

A total of 28 basidiomycetes and 16 substrates were investigated to detect extracellular peptidases for the hydrolysis of wheat gluten as a complex Koji substrate. In a first screening, basidiomycetes were grown in submerged cultures containing gluten as only carbon and nitrogen source. Growth rate, protein concentration and peptidase activity were monitored. Flammulina velutipes, Armillaria mellea, Trametes versicolor, Meripilus giganteus, Fomitopsis pinicola, Phanerochaete chrysosporium and Hericium erinaceus showed high peptidase activity. To evaluate the effects of complex substrates on peptidase generation, a set of experiments was performed using surface cultures of Flammulina velutipes. This fungus grew well on many of the substrates and yielded a maximum of over 160.000 arbitrary U mL⁻¹ on the surface liquid released from gluten pellets. Gelatin zymography visualized a complex mixture of secreted peptidases. Highest peptidase yield was obtained from a koji-type culture: A maximum of 63% of the gluten was converted to free amino acids in 14 days by peptidase activities in the range of 80,000–90,000 aU mL⁻¹. The dark brown hydrolysate smelled and tasted like meat broth with no detectable bitterness.     

Chemical Properties of a Polysaccharide Purified From Solid‐State Fermentation of Auricularia Auricular and its Biological Activity as a Hypolipidemic Agent

A water‐soluble crude polysaccharide was extracted by hot water from Auricularia auricular mycelium grown under solid‐state fermentation (SSF). The crude polysaccharide was purified by DEAE Sephadex A‐50 and Sephadex G‐200 chromatography. Fourier transform infrared spectroscopy and nuclear magnetic resonance (¹H NMR) spectroscopy were used to investigate the structure of the purified A. auricular polysaccharide (AAP‐I) and revealed that it is α‐glycosidically linked. After 14 and 28 days of AAP‐I orally administered, the AAP‐I significantly decreased the levels of total cholesterol, triglyceride, and low‐density lipoprotein cholesterol in mice in which hyperlipidemia had been induced by a high fat diet (P < 0.05). The results revealed that AAP‐I from SSF of A. auricular mycelium possesses potent hypolipidemic properties. The polysaccharide may be useful as a functional food additive and a hypolipidemic agent.     

Antioxidative Activities of Mushroom (Flammulina velutipes) Extract Added to Bigeye Tuna Meat: Dose‐Dependent Efficacy and Comparison with Other Biological Antioxidants

ABSTRACT: The ability of a hydrophilic extract prepared from edible mushroom (Flammulina velutipes) to stabilize fresh color of bigeye tuna (Thunnus obesus) meat was evaluated to compare it with certain other antioxidants. The fresh color shelf life of bigeye tuna meats, to which were added as 1, 3, or 5 mL of mushroom extract to 100 g of minced bigeye tuna meat, prolonged duration of ice storage by more than 2, 4, and 6 d, respectively, in comparison with the control tuna meat without mushroom extract. The addition of 5 mL of mushroom extract to 100 g of minced bigeye tuna meat was more effective than adding ascorbic acid sodium salt (500 ppm) or α‐tocopherol (500 ppm) with regard to oxidation of lipid in the tuna meat. The color changes significantly correlated with lipid oxidation as well as metmyoglobin formation in the tuna meat. These results clearly show that the mushroom extract is a potential antioxidant, which has the ability to stabilize fresh color of tuna meat during ice storage.     

The Applications of Polysaccharides from Various Mushroom Wastes as Prebiotics in Different Systems

The bases or stipes of mushrooms are normally discarded as low‐economic value animal feed and compost. There are no known reports on deriving polysaccharides from these mushroom wastes for use as prebiotics. This study showed that the relatively low concentration (0.1% to 0.5%) of polysaccharides from Lentinula edodes stipe, Pleurotus eryngii base, and Flammulina velutipes base can enhance the survival rate of Lactobacillus acidophilus, Lactobacillus casei, and Bifidobacterium longum subsp. longum during cold storage. The polysaccharides had synergistic effects with the peptides and amino acids from a yogurt culture to maintain probiotics above 10⁷ CFU/mL during cold storage, and they also had significant protective effects on these probiotics in simulated gastric and bile juice conditions to achieve beneficial effects in the host. These results showed that mushroom wastes, which are cheaper than other sources, could be an important, new, alternative source of prebiotics.     

Antimicrobial activity of Zataria multiflora Boiss. essential oil incorporated with whey protein based films on pathogenic and probiotic bacteria

The antimicrobial potential of whey protein isolate (WPI) edible films containing 1–4% (v/v) Zataria multiflora Boiss. essential oil (EO) on food‐borne pathogenic bacteria (Escherichia coli, Salmonella enteritidis, Staphylococcus aureus and Bacillus cereus) and probiotic bacteria (Lactobacillus acidophilus, Lactobacillus rhamnosus, Lactobacillus plantarum and Lactobacillus casei subsp. casei) was evaluated. WPI films incorporated with 2% (v/v) of this EO inhibited the growth of all tested pathogenic bacteria and gram‐negative bacteria were more sensitive than gram‐positive bacteria. Incorporation of the EO at higher than 2% (v/v) showed significant antimicrobial effects (P < 0.05) for S. enteritidis and L. acidophilus. The growth of all probiotic lactic acid‐producing bacteria also inhibited when 2% of the EO was added. Comparison of an image processing‐based method with conventional method for measuring of inhibitory effects of edible films exhibited high correlations (R² ≥ 0.876) between the two methods. These results revealed that Z. multiflora Boiss. EO is a good antimicrobial additive for some food applications when included into WPI edible films.     

Characterisation of microemulsion nanofilms based on Tilapia fish skin gelatine and ZnO nanoparticles incorporated with ginger essential oil: meat packaging application

Microemulsion nanofilms based on fish skin gelatine (FSG) and 3% (w/w, gelatine) ZnO nanoparticles (ZnONP) incorporated with ginger essential oil (GEO) at different concentration (10%, 20%, 40%, 80%, w/w, gelatine) were developed and characterised. Film thickness and elongation increased, while film tensile strength and gel strength decreased as GEO level increased (P < 0.05). The water vapour permeability was reduced (P < 0.05) by GEO. Microstructural study revealed a dispersion system with GEO lipid droplet embedded into FSG matrix and some aggregation. The developed films showed strong antibacterial activity against food spoilage bacterial of psychrotrophs, mesophiles and lactobacillus spp. (LAB) in situ, and food pathogenic bacteria of Escherichia coli and Listeria monocytogenes in vitro. Together with the antioxidant activity towards lipid oxidation, the release of total volatile bases nitrogen (TVB‐N) was subsequently reduced during fresh meat storage. In conclusion, the incorporation of GEO provided the potential to make FSG‐ZnONP films more available for meat storage.     

Inhibitory Effects of ‘Enokitake’ Mushroom Extracts on Polyphenol Oxidase and Prevention of Apple Browning

‘Enokitake’ mushroom (Flammulina velutipes) extracts were prepared by three different solvents: 70 mL/100 mL acetone, 70 mL/100 mL ethanol as well as hot water. Effects of the extracts on mushroom tyrosinase activity and browning of apple were investigated. Mushroom tyrosinase activities assayed spectrophotometrically and by oxygen uptake were found to be inhibited significantly by all three extracts. Lyophilized ‘enokitake’ fruit body powder inhibited the browning of fresh apple. Immersing sliced apple into the acetone extract was found to prevent effectively the browning development. Freshly squeezed apple juice with added hot-water extract showed the concentration-dependent inhibition of browning. No browning was observed on the apple juice when mixed with the extract containing 1.0 g wet ‘enokitake’/mL in a mixture. Under the same conditions, no significant changes in color in terms of a* and b* values of the mixture were observed for up to 6 h. These observations suggested that ‘enokitake’ mushroom contained certain compounds which inhibited mushroom tyrosinase activity and the development of browning induced by the catalytic oxidation due to polyphenol oxidase.     

QUALITY PRESERVATION OF COMMERCIAL FISH BALLS WITH ANTIMICROBIAL ZEIN COATINGS

ABSTRACT

To enhance the practical application of active edible coatings in the food industry, edible zein coatings incorporated with nisin (54.4 AU/cm²) or nisin/ethylenediaminetetraacetic acid (EDTA; 568 µg/cm²) were used to preserve the quality of commercially manufactured fish balls. The microbial load, total basic volatile nitrogen (TVB‐N) content and weight loss were served as quality indicators. The increase of microbial load of fish balls coated with antimicrobial zein during a 15‐day refrigeration storage period was less than 1 log cfu/g, while the microbial load increased about 3 log cfu/g for the control group without the coating treatment. The formation of TVB‐N was significantly (P < 0.05) reduced when fish balls were coated with antimicrobial zein. With or without antimicrobial agent, coated fish balls exerted significantly (P < 0.05) less weight loss than uncoated fish balls.

PRACTICAL APPLICATIONS

Although edible coatings or films containing bioactive substance have been intensively studied over the last few decades, most of these, still, have not had widespread commercial applications because the majority of studies were conducted with food‐simulated systems or food samples produced in laboratory. The fish balls commercially manufactured in a fishery product factory was used to demonstrate the efficacy of antimicrobial edible coating will enhance the confidence of food manufactures to apply the technology in their products.     

Factors affecting the uptake of lead and copper in five wild mushroom species from Chengdu,China

A comparison was made of the lead and copper content of five wild-growing mushroom species. A significant variation in lead levels was found between caps and stalks in Lepista sordida. A clear difference between old and young fruiting bodies was found for copper contents in Coprinus atramentarius. Both lead and copper content were found to increase initially and then decrease with increasing fungal size of Coprinus atramentarius and Flammulina velutipes with asynchronous turning points. In Cortinarius cinnamomeus, the lead and copper content was significantly correlated with the NH₄OAc/EDTA extractable fractions (Pb: r = 0.98; Cu: r = 0.96) in the topsoil rather than pH values, organic matter content, cation exchange capacity or even the total metal (except copper) levels (Cu: r = 0.99, p < 0.05). Additionally, soil-growing mushroom species seemed to accumulate copper similarly (BCF > 1.0), while variously excluding lead (BCF < 1.0), but both the metal concentrations are relatively low compared with relevant statutory levels or other reported values.     

Influence of temperature,calcium and sucrose concentration on viscoelastic properties of Prosopis chilensis seed gum and nopal mucilage dispersions

Viscoelastic properties of two nontraditional hydrocolloid dispersions were evaluated. Prosopis chilensis seed gum was evaluated based on temperature (5–80 °C) and added CaCl₂ (0.07%), whereas nopal mucilage was evaluated based on temperature (5–80 °C) and sucrose concentration (0–20%). Viscoelasticity was tested by the small strain oscillatory shear test; storage modulus (G′), loss modulus (G″) and tan δ were reported. Prosopis chilensis and nopal dispersions behaved as weak gels (G’ > G’’) regardless of experimental condition. Raising temperature from 20 to 80 °C significantly increased G’. The gel structure was strengthened by adding CaCl₂ and G’ increased at 40 °C. The sucrose effect depended on concentration and temperature; at low sucrose concentrations, G’ modulus increased regardless of temperature level, but at high concentrations, it decreased at temperatures >40 °C. In conclusion, nopal and Prosopis chilensis dispersions show weak gel structure regardless of experimental condition. G′ increases as temperature increases, and these dispersions could be suitable for food applications requiring heat tolerance.     

黑木耳多糖研究进展

黑木耳是一种营养价值极高的药食两用真菌.综述了国内外黑木耳多糖研究情况,对其热水浸提法、碱浸提法、酶解提取法、超声波法、微波辅助法、超微粉碎法以及复合法几种提取制备方法进行比较,并对黑木耳的深加工及功能食品开发作了介绍.     

添加血耳发酵液的鲜湿热干面研制

为提高鲜热干面的食用品质并实现血耳发酵液的有效利用,本研究以感官评价、蒸煮品质和质构为评价指标,探究了血耳发酵液的浓度,血耳发酵液、食盐、食用碱和谷朊粉添加量对鲜湿热干面食用品质的影响,并利用综合评分法对添加血耳发酵液的鲜湿热干面配方进行优化。结果表明:各因素对鲜湿热干面食用品质的影响顺序依次为食用碱食盐谷朊粉血耳发酵液,最优的鲜湿热干配方为在100 g面粉中,添加浓度为100%血耳发酵液34 mL、食盐1 g、食用碱0.3 g、谷朊粉2 g,该条件下制得的鲜湿热干面的食用品质最佳,综合评分为81.05,感官评分为86.67分,断条率为0,蒸煮损失率仅为5.13%,蒸煮吸水率为68.31%,且优化后鲜湿热干面的货架期延长1倍。本研究为食用菌功能性主食开发提供了思路和依据。     

Inactivation of Salmonella in Shell Eggs by Hot Water Immersion and Its Effect on Quality

Thermal inactivation kinetics of heat resistant strains of Salmonella Enteritidis in shell eggs processed by hot water immersion were determined and the effects of the processing on egg quality were evaluated. Shell eggs were inoculated with a composite of heat resistant Salmonella Enteritidis (SE) strains PT8 C405, 2 (FSIS #OB030832), and 6 (FSIS #OB040159). Eggs were immersed in a circulating hot water bath for various times and temperatures. Come‐up time of the coldest location within the egg was 21 min. SE was reduced by 4.5 log at both hot water immersion treatments of 56.7 C for 60 min and 55.6 °C for 100 min. Decimal reduction times (D‐values) at 54.4, 55.6, and 56.7 °C were 51.8, 14.6, and 9.33 min, respectively. The z‐value was 3.07 °C. Following treatments that resulted in a 4.5 log reduction (56.7 °C/60 min and 55.6 °C/100 min), the surviving population of SE remained static during 4 wk of refrigerated storage. After processing under conditions resulting in 4.5 log reductions, the Haugh unit and albumen height significantly increased (P < 0.01) and yolk index significantly decreased (P < 0.05). The shell dynamic stiffness significantly increased (P < 0.05), while static compression shell strength showed no significant difference (P < 0.05). Vitelline membrane strength significantly increased (P < 0.05); although, no significant difference (P < 0.05) was observed in vitelline membrane elasticity. In summary, the hot water immersion process inactivated heat resistant SE in shell eggs by 4.5 log, but also significantly affected several egg quality characteristics.