EMULSION COATING TO EXTEND POSTHARVEST LIFE OF MANGO (MANGIFERA INDICA CV. MANILA)

A coating emulsion was prepared using maltodextrins, carboxymethylcellulose, propileneglycol and a mixture of s orbit an fatty acid esters with an HLB of 6. The emulsion was sprayed on fully mature, unripened manila mangoes, which were the stored at 15 and 25C and 80–85% R.H. At 25C it was observed that rate CO² production increased and lost in control fruits after 12 days of storage. Coated mangoes kept their rate CO² production and suffered only 8% weight loss after 21 days of storage. After storage, the coating was washed out and fruits were allowed to ripen naturally, which occurred in 3–4 days. The results obtained from this study indicate that application of the hydrophobic coating extended the postharvest storage of mangoes for at least 20 days more than uncoated fruits.     

A UNIFIED COLLOCATION ALGORITHM FOR PACKED-BED CHEMICAL REACTOR SIMULATION

Mathematical models of packed-bed catalytic reactors are aimed to predict the conversions and temperature profiles in both fluid and solid phases within the reactor. Although very general models can be mathematically formulated, usually several simplifying hypothesis are introduced for the fluid phase and/or the solid phase, in order to overcome computational difficulties

We describe in this paper a computational algorithm based on Orthogonal Collocation Method on finite elements, with elimination of the knot unknown functions, coupled with an integration method for stiff ordinary differential equations. This has been used in the development of a computer code, which allows us to find the transient behavior of the reactor by solving the equation relative to the external field, coupled with those describing the transient behavior in the catalyst particles, for a wide class of reactor models. The most general examined model includes axial dispersion in the external fluid phase, interphase mass and heat transfer resistances, intraphase mass resistance and any given kinetic scheme with complex reaction rate expressions.     

EXTRACTION OF PROTEINS FROM BUCKWHEAT BRAN

ABSTRACT Proteins from buckwheat bran were extracted by a wet alkaline extraction process, giving a yield of 37.0%of the total nitrogen in the liquid extract, at pH of 6.5. However, the yield could be improved, given a pretreatment of the bran with carbohydrases, thus producing a yield of 56% with cellulase, 58%with pectinase, whereas the increase was minimal with hemicellulase. The maximum yield of 67.5%was obtained by synergistic action of pectinase and hemicellulase, in a pretreatment lasting for 7 h at pH of 3.7.     

Ascorbic, Dehydroascorbic and Isoascorbic Acid Simultaneous Determinations by Reverse Phase Ion Interaction HPLC

Detection was by UV absorbance (after pre-column derivatization of dehydroascorbic acid with 1,2-phenylenediamine). When absent, isoascorbic acid could be used as internal standard. Isocratic separation was accomplished in 11 min using the eluent, methanol-water (5:95, v/v) containing potassium dihydrogen phosphate (50 mM) and the counterion hexadecyltrimethylammonium bromide (5 mM). Sample preparation steps using Sep-pak C18 cartridge were minimal. Ten ppm could be detected for each compound with good reproducibility (c.v. <2%). The method was used to determine vitamin C content in selected foods and beverages.     

Discrete-time linear periodic systems: gramian and modal criteria for reachability and controllability†

This paper deals with the reachability and controllability of periodic discrete-time systems. First, we supply two necessary and sufficient complete reachability conditions, which apply to reversible and non-reversible systems, respectively. Then, a necessary and sufficient complete controllability condition is provided. This condition, as well as the complete reachability criteria, is given in terms of the reachability gramian matrix. Equivalent modal criteria for reachability and controllability are established in the second part of the paper.     

Rheology Aspects of Leather Finishing Formulations

The rheological properties of leather finishing formulations were investigated. The rheological analysis was performed in a Ford cup number 4, a Brookfield viscometer, and a rheometer. The effects of the formulation parameters on the viscosity behavior showed similar trends for each technique. The tests in the rheometer showed that soft acrylic resins produced shear thinning formulations, similar to the effect of the finishing pigments. Furthermore, samples containing soft resins and polymeric pigments produced formulations with elastic properties. Finally, the Ford viscosity does not change significantly with the formulation parameters as the Brookfield viscosity does (type of pigment, resin, or resin-pigment ratio). Thus, the non-Newtonian behavior shown by the finishing samples analyzed suggests avoiding the use of the Ford cup when assessing leather finishing formulations. The Brookfield viscometer, however, would provide more reliable viscosity values when a rheometer is not at hand.     

A MODIFICATION OF THE HELIOSAT METHOD TO IMPROVE ITS PERFORMANCE

The article presents a modification of the Heliosat Method which has been proven to give a better estimation of solar radiation. In the modified algorithm, the absence of a cloud above each pixel is checked from its cloud cover index value, and if no cloud is detected, the global radiation incident on the pixel is computed using a clear sky model. Otherwise, the quantity is calculated following the original algorithm. The improvement obtained from the modification has been evaluated at a Heliosat Secondary User Station in Italy. The evaluation was done by comparing the hourly global irradiation estimated by the original method and that determined by the modified method with the values measured directly at 13 ground stations. The improvements of the global root mean square error and mean bias error computed from the combined data of all the 13 stations are 5.17% and 8.03% of the mean ground measured hourly irradiation, respectively. The improvements for the individual stations are as reported in Table 1.

Based on the results of the evaluation, it has been concluded that the proposed modification gives a better estimation of the energy than the original algorithm. The improvement is more pronounced especially when the method is used in countries or regions where cloudless atmospheric conditions prevail for relatively longer periods of the year.