Chemical composition and non-volatile components of Croatian wild edible mushrooms

The chemical composition (dry matter, crude protein, crude fat, total carbohydrates, and ash) and non-volatile components content (soluble sugars, free amino acids, and 5′-nucleotides) of 10 popular Croatian wild edible mushroom species (Agaricus campestris, Boletus edulis, Calocybe gambosa, Cantharellus cibarius, Craterellus cornucopioides, Entoloma clypeatum, Flammulina velutipes, Macroleptiota procera, Morchella elata, and Pleurotus ostreatus) were determined. All investigated mushrooms were found to be good sources of proteins and total carbohydrates, with contents varying in the ranges of 27.95–38.89, and 42.62–66.78 g/100 g, respectively. In addition, the fat contents were very low 1.34–6.45 g/100 g. B. edulis (19.87 mg/g) showed the highest concentration of essential amino acids and M. elata (14.25 mg/g) the lowest concentration. Monosodium glutamate-like components and total flavour 5′-nucleotides were the highest in C. cornucopioides (45.85 and 13.88 mg/g, respectively), and lowest in F. velutipes (7.63 and 1.05 mg/g, respectively). Equivalent umami concentration values in 10 Croatian wild edible mushrooms ranged from 73.78 to 1186.45 g MSG/100 g dry weight, and overall, all these mushrooms possessed highly umami taste.     

Antioxidant properties of commercial wild rice and analysis of soluble and insoluble phenolic acids

To investigate the antioxidant properties of commercial wild rice, identify and quantify soluble and insoluble phenolic acids in wild rice whole grain, the alkaline hydrolysates from crude methanol extracts (soluble fraction) and residues (insoluble fraction) were separately analysed by high performance liquid chromatography (HPLC) coupled with photodiode array detection (PAD) and quadrupole-time of flight (Q-TOF) mass spectrometry (LC–MS). The antioxidant activity of wild rice methanol extract was found to be up to 10 times greater than that of white rice (control sample) according to their 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and oxygen radical absorbance capacity (ORAC). Ferulic acid was found as the most abundant phenolic acid (up to 355 mg/kg) followed by sinapic acid in wild rice. They both occurred mainly in the insoluble form. Other monomeric phenolic acids present in wild rice consisted of p-coumaric, vanillic, syringic, and p-hydroxybenzoic acids, along with two phenolic acid aldehydes (p-OH-benzaldehyde and vanillin). They were present in both soluble and insoluble forms. Phenolic acid dehydrodimers are cell wall bound and only appeared in the insoluble fractions featured by diferulic acids (DiFA) and disinapic acids (DiSA). The chemical structures of DiFA included 8-8′, 5-5′, 8-O-4′, and 8-5′ (benzofuran form) coupled dimers, with 8-O-4′ as the predominant form (up to 34 mg/kg). DiSA only appeared as 8-8′-coupled products with the linear isomers in the most quantities (up to 19 mg/kg). The DPPH free radical scavenging activities of soluble and insoluble fractions suggest that the antioxidant activity of wild rice is partially attributed to its phenolic acid profile.     

HPLC-MS/MS法测定酸枣汁中VC含量

建立HPLC-MS/MS法检测酸枣汁中维生素C的含量。该方法应用超声提取和Agilent G6410B Triple Quad LC/MS检测。Waters YMCTMODS-AQ S-5 120A(2.0×100 mm)分析柱,流动相为甲醇-水(0.1%甲酸)=50∶50;流速0.3 mL/min;柱温30℃,进样量为20μL。以液相色谱分离、电喷雾离子化串联质谱进行检测。VC在50 ng/mL~800 ng/mL范围内线性关系良好,酸枣汁中VC平均加标回收率为98.61%。该方法快速简便、精密度好、灵敏度高,可用于酸枣汁中VC的含量测定。     

Optimization of an active package for wild strawberries based on the release of 2-nonanone

Active packaging is becoming in an emerging food technology to improve quality and safety of food products, commonly based on the retention or release of compounds which are beneficial for the product. In this work, an active packaging system based on the release of 2-nonanone has been optimized to increase the postharvest shelf life of fresh wild strawberries during the marketing stage. To avoid that excessive levels of this volatile could affect the berries' taste and cause consumer rejection of the product, a preliminary sensory analysis was carried out to determine the threshold value of 2-nonanone, 7.16 mg/kg fresh wild strawberries. Taking this threshold value into account, diverse quantities of 2-nonanone were tested to optimize the packaging parameters. Wild strawberry fruits were packaged in the active packages developed and their quality monitored during storage at 10 °C with exposure to light to simulate real-life conditions on supermarket shelves. The analyses of weight loss, SSC, gas composition and aroma volatiles provide evidences that exposure to the highest-tested 2-nonanone concentrations are an effective way of maintaining the quality of wild strawberries during distribution and sale without modifying their typical taste.