Hydrolytic degree and antioxidant activity of purified casein characterised by different haplotypes (αs1-, β- and k-casein) after enzymatic hydrolysis with pepsin and enzymatic extract from Pleurotus eryngii

The aim of this study was to estimate the hydrolytic degree and antioxidant activity of purified casein characterised by different haplotypes (α_s1-, β- and k-casein) after in vitro digestion with two different enzymatic systems: pepsin from porcine gastric mucosa (EP) and a crude enzymatic extract from the edible mushroom Pleurotus eryngii. The used enzymes showed a different mode of casein catalysis with a consequent production of peptides of different antioxidant activity. The CN haplotype significantly influenced peptides production; in fact, the amino acid substitutions caused by genetic polymorphisms at the α_s1-, β- and k-CN loci influenced the sites of enzymatic cleavage and therefore the produced peptides. The above is evidenced by the different antioxidant activity found in the hydrolysates depending on the used enzymatic system, the CN haplotype, and the CN haplotype × enzymatic treatment interaction. The findings of this study are a perspective for the production of specific foods that exert a biological effect in addition to the nutritional one.     

Use of coffee by‐products for the cultivation of Pleurotus citrinopileatus and Pleurotus salmoneo‐stramineus and its impact on biological properties of extracts thereof

Incorporating spent coffee grounds (SCGs), a by‐product from coffee brewing, in growth substrate of beneficial edible mushrooms is an approach that has to be further studied due to its potential positive outcomes: environmental impact mitigation, production costs reduction and beneficial impact on consumer health. Hence, cultivation of Pleurotus citrinopileatus and Pleurotus salmoneo‐stramineus was tested using SCG which enabled maximum production yield of P. citrinopileatus which was of 25.1% (w/w). Variable antidiabetic potential was observed between aqueous and enzymatic extracts (3.8%–29% inhibition) regardless species and substrates, whereas aqueous extract of P. citrinopileatus grown in substrate without SCG stood out presenting the highest antioxidant activity and inhibition activity of angiotensin I‐converting enzyme (IC₅₀ = 123 μg mL^?1). Ethanolic and aqueous extracts of both Pleurotus species grown in the presence or absence of SGC proved to be an interesting prebiotic source for growth of Bifidobacterium animalis Bo in comparison with fructooligosaccharides (FOS).     

Effects of Phosphoryl Oligosaccharides of Calcium (POs-Ca) on Mycelial Growth and Fruiting Body Development of the Edible Mushroom,Pleurotus ostreatus

Phosphoryl oligosaccharides of calcium (POs-Ca) is a calcium salt of phosphoryl maltooligosaccharides made from potato starch. POs-Ca is highly water-soluble and can supply both the calcium ion and acidic oligosaccharides in an aqueous solution. In this study, we investigated the effects of POs-Ca on the mycelial growth and fruiting body yield of Pleurotus ostreatus , which is one of the most widely cultivated edible mushrooms in the world. We cultivated the mushroom using both potato dextrose agar (PDA) medium and sawdust-based medium, with added calcium salts. The addition of POs-Ca into the PDA medium with a calcium concentration of 10 mg increased mycelial growth significantly ( p < 0.05, vs . control). POs-Ca addition to the sawdust-based medium at concentrations of 1.0 to 3.0 g/100 g medium increased the amount of calcium in the fruiting bodies but did not affect the length of the cultivation period or the weight of the fruiting body. The calcium content in the fruiting body increased 12-fold when compared to the control. On the other hand, neither the CaHPO ₄ ･2H ₂ O group nor the CaHPO ₄ ･2H ₂ O with oligosaccharides group showed changes in the calcium content of the fruiting bodies. Our results indicate that the use of POs-Ca in mushroom cultivation allows for the possibility of developing new functional foods like calcium-enriched edible mushrooms. This is the first report describing the effects of POs-Ca on mushroom cultivation.     

Pleurotusostreatus and Agaricus subrufescens: investigation of chemical composition and antioxidant properties of these mushrooms cultivated with different handmade and commercial supplements

In this study, the chemical composition, total phenolic content and antioxidant activity (DPPH, ORAC and FRAP assays) of A. subrufescens and P. ostreatus, cultivated with handmade and commercials supplements, were compared. Additionally, the compounds ergosterol, saccharopine, and hexitol were identified in A. subrufescens by HPLC-MS/MS. The antioxidant compound p-coumaric acid and dihexoses was found in both mushroom species. A. subrufescens presented higher total phenolic content (73.8 ± 0.6 mg GAE 100 g⁻¹) and antioxidant activity than P. ostreatus (16.6 ± 0.5 mg GAE 100 g⁻¹). The handmade supplement based on the waste of noble grains presented statistically similar phenolic content to the mushrooms cultivated with commercial ones Spawn Mate II SE (86.1 ± 1.4 and 92.9 ± 0.3 mg GAE 100 g⁻¹, respectively). Therefore, the results support the use of handmade supplements based on agro-wastes as a viable alternative to the use of high-cost commercial ones.     

杏鲍菇富硒蛋白的营养结构特性及对铅毒性的缓解作用

铅主要通过饮食进入人体并在体内积累，对人体免疫和代谢等系统造成损伤，补充硒可以显著改善铅暴露对机体的危害。本研究以杏鲍菇富硒蛋白（selenium-enriched protein from Pleurotus eryngii，SePEP）为原料，通过高效液相色谱-电感耦合等离子体质谱联用技术、傅里叶变换红外光谱等测定蛋白硒形态及结构。通过细胞实验探究蛋白体外模拟消化产物对Pb2＋引起的RAW264.7细胞毒性的缓解作用。结果表明，SePEP硒含量为（360.64±3.11）mg/kg，硒形态主要包括硒代蛋氨酸（SeMet，（48.04±0.64）%（相对含量，下同））、硒代胱氨酸（SeCys2，（31.91±0.51）%）和甲基硒代半胱氨酸（MeSeCys，（14.65±0.36）%）。硒的添加显著促进了氨基酸的生成，改变了蛋白质的结构，α-螺旋结构相对含量由（20.30±0.87）%增加至（25.00±1.60）%，无规卷曲结构相对含量由（20.38±0.84）%减少至（13.85±1.66）%，总巯基与二硫键含量及表面疏水性均显著增加（P＜0.05）。添加75 μg/mL SePEP消化产物后，Pb2＋处理的RAW264.7细胞存活率由接近50%显著升高至（76.95±6.95）%，细胞培养液中乳酸脱氢酶释放量降低57.45%，并且3 种促炎细胞因子白细胞介素（interleukin，IL）-6、IL-8和肿瘤坏死因子α的释放受到显著抑制（P＜0.05），说明SePEP消化产物对Pb2＋暴露引起的RAW264.7细胞损伤有缓解作用。本实验研究成果可为研发安全、有效的改善铅毒性的功能富硒蛋白食品提供参考。     

Effects of different agro-industrial waste as substrates on proximate composition,metals, and mineral contents of oyster mushroom (Pleurotus ostreatus)

The use of agro-industrial waste as substrates for mushroom cultivation is considered a promising management strategy for reducing and valorising these wastes, simultaneously reducing the cost of mushroom cultivation. In this study, oyster mushroom Pleurotus ostreatus were cultivated on twelve substrates composed of either tea waste, lime sawdust, alder sawdust, hornbeam sawdust/shaving, wheat stalk-straw, wheat bran or their composite to determine the proximate composition and accumulation of thirteen elements in their fruiting bodies. The proximate composition of P. ostreatus did not show a significant difference, regardless of the employed substrate. (one-way manova ; F_{(66, 107)} = 1.329, Wilk’s λ = 0.041, P > 0.05). However, their chemical element contents show a statistically significant difference (one-way manova ; F_{(132, 418)} = 32.163, Wilk’s λ = 0.000, P < 0.05). These results were supported by discriminant function and principal component analyses. The highest mean concentrations of six of twelve elements (i.e., Ca, Mg, Na, Zn, Cd and Cr) were recorded in P. ostreatus cultivated on the lime-sawdust substrate. Three health indices viz., estimated daily intake, target hazard quotient (THQ) and total THQ were applied to determine the risk to human health via the consumption of P. ostreatus, suggesting that they are safe for human consumption.     

Effects of different carbon sources and C/N values on nonvolatile taste components of Pleurotus eryngii

Pleurotus eryngii, the second largest industrial cultivation mushroom in China, is usually cultivated on substrates mainly consisting of sawdust and corncob. In this study, experiments were performed to determine the effects of different carbon sources and C/N values on nonvolatile taste components of P. eryngii. The effects of different carbon sources on nonvolatile taste components levels revealed that sawdust was beneficial to high levels of crude protein, amino acids, 5′‐nucleotides and equivalent umami concentration, while corncob was beneficial to high contents of carbohydrate, polysaccharides and trehalose. At the similar C/N values, relatively higher sawdust content was beneficial to umami amino acid production, while relatively higher corncob content was beneficial to high contents of carbohydrate, polysaccharides and mannitol. Higher C/N value was beneficial to high levels of crude protein, amino acids, 5′‐nucleotides and equivalent umami concentration, while lower C/N value was beneficial to high contents of carbohydrate, polysaccharides and trehalose. These results provided information for P. eryngii fruit body industrial cultivation to obtain specific nonvolatile taste components with high levels.     

阿魏菇多糖高产菌株筛选的离子束诱变和复合诱变对比研究

为筛选出阿魏菇菌丝体多糖高产菌株，本文进行了阿魏菇多糖高产菌株筛选的离子束诱变和复合诱变对比研究。尝试用打散的阿魏菇菌丝体为靶材，以离子束注入为诱变手段，通过营养缺陷型初筛和摇瓶发酵复筛，获得了2株阿魏菇多糖高产菌株PFPH-1和PFPH-2。其菌丝体多糖产量分别达到551．80mg，L和659．46mg／L，比出发菌株分别提高了46．55％和75．14％。再分别以PFPH．1和PFPH．2为出发菌株，用紫外线和氯化锂进行复合诱变处理，通过高通量初筛和摇瓶发酵复筛，结果发现，菌株1、9和10号比其出发菌株PFPH-1的多糖产量分别减少了27％、38％和37％；菌株17号比其出发菌株PFPH-2的多糖产量减少了28％。在本研究中，紫外线和氯化锂的复合诱变表现出了一定的负效应。