Effect of thickness of polyethylene packaging and temperature on quality of solar-dried oyster mushroom (Pleurotus sajor-caju)

Pleurotus sajor-caju is evaluated as an edible fungi with high nutritional and medicinal value, but fresh mushrooms are easily damaged after harvest due to many reasons. Drying methods can be taken to maintain mushroom quality, reduce losses and prolong postharvest storage time. The objective of this study was to evaluate the effects of polyethylene (PE) packaging thickness (91.70 µm; 81.30 µm and 53.50 µm), temperature (28 oC-30 oC and 3 oC-5 oC) (with air humidity of 60-62% and 76-78% respectively), to the quality of oyster mushrooms dried by solar energy, during storage. During the storage period, the total sugar and protein contents of all treatments decreased. Besides, the colour (through the difference in lightness and darkness (?L) value) and firmness of the solar-dried oyster mushrooms also decreased, so, oyster mushrooms were darkened and softened. After 6 months, the lowest protein, total sugar and lipid loss was found in PE packaging of 91.70 µm thickness at storage temperature of 3 oC-5 oC. In addition, the water activity of dried mushrooms was lower (less than 0.7), so it ensures microbiological safety

Oil price shocks against stock return of oil- and gas-related firms in the economic depression: A new evidence from a copula approach

This research examines the influence of world crude oil price shocks on the financial performance of Vietnamese oil- and gas-related firms. Based on copula approach and the sample data of domestic giant oil- and gas firms from 2009 to 2019, in particular in the situation of oil price steadily going up and economic depression of 2011–2012; approximately nine copulas including Gauss, Clayton, Rotated-Clayton, Plackett, Frank, Gumbel, Rotated-Gumbel, Student, Symmetrized-Joe-Clayton have been focused. A new evidence could be found that the oil price shocks have not impacted on the stock return of oil- and gas-related firms in the wave of increasing oil price, but a lagged period of time oil- and gas-related firms could receive more stock returns. The results further demonstrate that world oil price fluctuations have significantly impacted on the financial performance of some firms as PVS, PVG, and PET in the pre-depression period. In respect to the economic depression of 2011–2012, the study reveals no evidence in the relationship between world oil price fluctuations and stock returns of oil- and gas-related firms. In other words, results in the post-depression period suggest that world oil price shocks can affect stock returns of selected giant oil- and gas-related firms