No abstract

The beta regression is a widely known statistical model when the response (or the dependent) variable has the form of fractions or percentages. In most of the situations in beta regression, the explanatory variables are related to each other which is commonly known as the multicollinearity problem. It is well-known that the multicollinearity problem affects severely the variance of maximum likelihood (ML) estimates. In this article, we developed a new biased estimator (called a two-parameter estimator) for the beta regression model to handle this problem and decrease the variance of the estimation. The properties of the proposed estimator are derived. Furthermore, the performance of the proposed estimator is compared with the ML estimator and other common biased (ridge, Liu, and Liu-type) estimators depending on the mean squared error criterion by making a Monte Carlo simulation study and through two real data applications. The results of the simulation and applications indicated that the proposed estimator outperformed ML, ridge, Liu, and Liu-type estimators.

The strawberry has a very short postharvest life due to its fast softening and decomposition. The goal of this research is to see how well a starch-silver nanoparticle (St-AgNPs) coating affects the physical, chemical, and microbiological qualities of strawberries during postharvest life. Additionally, the effect of washing with running water on silver concentration in coated strawberry fruit was studied by an inductively coupled plasma-optical emission spectrometer (ICP-OES). Furthermore, the shelf-life period was calculated in relation to the temperature of storage. Fourier transform infrared-attenuated total reflectance (FTIR-ATR), UV-Visible, and Transmission Electron Microscopic (TEM) were used to investigate the structure of starch-silver materials, the size and shape of AgNPs, respectively. The AgNPs were spherical, with an average size range of 12.7 nm. The coated samples had the lowest weight loss, decay, and microbial counts as compared to the uncoated sample. They had higher total acidity and anthocyanin contents as well. The washing process led to the almost complete removal of silver particles by rates ranging from 98.86 to 99.10%. Finally, the coating maintained strawberry qualities and lengthened their shelf-life from 2 to 6 days at room storage and from 8 to 16 days in cold storage.

Apricots are a fragile fruit that rots quickly after harvest. Therefore, they have a short shelf-life. The purpose of this work is to determine the effect of coatings containing chitosan (CH) as well as its nanoparticles (CHNPs) as thin films on the quality and shelf-life of apricots stored at room (25 ± 3 °C) and cold (5 ± 1 °C) temperatures. The physical, chemical, and sensorial changes that occurred during storage were assessed, and the shelf-life was estimated. Transmission electron microscopy was used to examine the size and shape of the nanoparticle. The nanoparticles had a spherical shape with an average diameter of 16.4 nm. During the storage of the apricots, those treated with CHNPs showed an obvious decrease in weight loss, decay percent, total soluble solids, and lipid peroxidation, whereas total acidity, ascorbic acid, and carotenoid content were higher than those in the fruits treated with CH and the untreated fruits (control). The findings of the sensory evaluation revealed a significant difference in the overall acceptability scores between the samples treated with CHNPs and the other samples. Finally, it was found that CHNP coatings improved the qualitative features of the apricots and extended their shelf-life for up to 9 days at room temperature storage and for 30 days in cold storage.

Strawberry is a non-climacteric fruit but exhibits very limited postharvest life due to its rapid softening and decay. Therefore, the current study was carried out to evaluate the effect of edible coatings using chitosan (CH) and chitosan nanoparticles (CHNPs) to improve the quality and extending the shelf life of strawberries during storage. Chitosan nanoparticles (CHNPs) were prepared by an ionic gelation method. The size and shape of the synthesized CHNPs were observed by transmission electron microscopy (TEM) technique. The strawberry samples were stored (after coating) at ambient temperature (25±3°C) and cold temperature (6±2°C) then, we evaluated the effectiveness of edible coating for physicochemical and microbiological properties, as well as the shelf-life during storage. The results of the TEM showed that the average particle size was 18.8-21.8 nm. At the different temperatures of storage, the samples coated with CHNPs had lower values of weight loss, decay, total soluble solids, and malondialdehyde concentrations. The same treatment had higher levels of total acidity and anthocyanin compared to the CH and uncoated treatments, that lead to preserving their quality properties and extending the shelf-life. Also, counts of total aerobic, mold, and yeast for strawberry samples treated by CHNPs were lower than those for CH and control treatment during the storage. In conclusion, the antimicrobial edible coating by CHNPs improved the qualitative characteristics and increased the shelf-life from 2 to 6 days for fruits stored at 25±3°C and from 8 to 16 days for samples stored at 6±2°C.