ACOUSTIC IMPULSE RESPONSE FOR MEASURING THE FIRMNESS OF MANDARIN DURING STORAGE

The objective of this research was to evaluate the ability of acoustic impulse response for monitoring the mandarin firmness change during storage. The dominant resonant frequency, stiffness coefficient (SC) and elasticity coefficient (EC) decrease with storage time. A good correlation was established between the acoustic parameters (SC and EC) and fruit compression force, and the correlation coefficients were 0.88 and 0.92, respectively. Acoustic impulse response gives a good indication of firmness change for mandarin during storage. The change of EC was more prominent (greatest), and hence it can be a better index of mandarin firmness. The nondestructive acoustic test might replace conventional destructive test for mandarin to determine fruit firmness and expected shelf life.     

GROWTH OF EUROTIUM CHEVALIERI IN MILK JAM: INFLUENCE OF PH, POTASSIUM SORBATE AND WATER ACTIVITY

Milk jam (dulce de leche) is a typical Argentine sweet spread prepared by milk evaporation to about 70% w/w total solids at atmospheric pressure with added sucrose, glucose and vanillin. Growth of xerophilic molds represents a severe problem in this type of intermediate moisture product. This study evaluated the growth response of Eurotium chevalieri in milk jam with different potassium sorbate (KS) concentrations (0, 500, 1,000, 1,500 and 2,000 ppm) at selected water activity (a_w) values (?0.80 and 0.85) and two pH levels (?5.5 and 6.0) stored at room temperature (25C) for 90 days. Growth curves were characterized by the modified Gompertz model, and the effect of the independent variables on the estimated parameters (maximum specific growth rate, v_m, and lag time, λ) was analyzed through polynomial equations. Growth of E. chevalieri was prevented for at least 90 days when the addition of 1,000 ppm KS was combined with a decrease in a_w to 0.80 and ph 5.5. The boundary between growth and nongrowth of E. chevalieri as a function of a_w, pH, KS and storage time was also predicted by means of the probabilistic model using logistic regression, which provided a wide range of formulation possibilities depending on the targeted shelf life.     

Laboratory and Pilot Scale Recovery of Protein from Mechanically Separated Chicken Residue

Bone residue resulting from mechanical deboning of chicken backs and necks was subjected to alkali extraction followed by acid precipstation to recover food grade protein. A laboratory study of effects of varying die size in the grinding of the starting material, of extraction temperature, and of g-force during centrifugation on composition of process fractions was conducted. Grinding increased ash content, higher temperature reduced fat content, and increasing centrifugal force decreased ash content, of the final products. Effects of grinding, extraction temperature, and centrifugal type were also studied on a pilot scale. Final protein product yield was higher at a 22°C than at a 3–7°C extraction temperature, and less fat was incorporated using a basket centrifuge than with a horizontal decanter centrifuge.     

Microcomputer-Aided Evaluation of Earthquake-Induced Permanent Slope Displacements

Ageotechnical engineering microcomputer program has been developed for the determination of permanent slope displacements resulting from earthquake shaking. The Newmark procedure, in which accelerations in excess of yield accelerations are double integrated to obtain displacements, has been incorporated into the program DISPLMT. Several user options are available for describing the yield acceleration function, including variation with time and variation with displacement. Screen graphics are available which allow the user to observe the down slope movements of the Newmark sliding block as they increase with time during the simulated earthquake. DISPLMT has been used to calculate the permanent movements of an earth dam using acceleration-time histories and soil shear stresses determined from a separate analysis. Modification to the conventional Newmark procedure, by introduction of a "slip layer," has been made in the analysis of a dam. Permanent slope displacements can be analyzed using the recommended procedure, which involves fairly simple computations that can be performed in a reasonable period of time with the exclusive use of microcomputers.     

Analysis of shearing stress in the limited durability of bovine pericardium used as a biomaterial

The objective of the study was to determine the shearing stress exerted by the suture thread under conditions of normal working stress. Thirty-six samples of calf pericardium, similar to that employed in the manufacture of bioprosthetic cardiac valve leaflets, were subjected to tensile testing. Prior to the trial, a continuous suture was sewn in the central zone of each sample, at a 45° angle to the longest axis of the sample, using commercially-available threads (silk, Gore-Tex, Surgilene and nylon). Application of the Mohr circle for combined wear revealed that the shearing stress ranged between 2.68-fold greater (for samples sewn with silk) and 5.48-fold greater (for samples sewn with nylon) than the working tensile stress in the region of the suture. It is concluded that the shearing stress is responsible for the limited durability of sutured samples of calf pericardium prepared to simulate bioprosthetic cardiac valve leaflets. © 1998 Chapman & Hall     

EFFECT OF PROTEIN SYNTHESIS INHIBITORS ON THE CLIMACTERIC OF BANANA (Musa acuminata)

Protein synthesis inhibitors (Actinomycin D and cycloheximide) were infiltrated into banana slices by contact or under vacuum. Drastic reduction of the climacteric period was observed in both types of infiltration when cycloheximide was infiltrated into slices, compared to the Actinomycin D group and to a control group infiltrated with water. Ethylene production was stimulated when both protein synthesis inhibitors were used, in comparison to the water control group irrespective of the type of infiltration adopted. Ethylene production was higher in the vacuum infiltrated groups. It is suggested that cycloheximide and Actinomycin D affect the equilibrium of ripening differently, giving rise to the distinct responses observed.     

EFFECT OF PROTEOLYTIC ENZYMES ON COLOR CHANGES IN BANANA CHIPS DURING OSMOTIC DEHYDRATION

ABSTRACT

The effect of papain and microbial Multifect P -- 3000 on color parameter changes: L, hue and chroma in banana slices (border and central part) during four hours of osmotic dehydration were studied. These enzymes did not control color changes in banana slices and were not found on the surface of dehydrated chips. Neither papain nor Multifect P -- 3000 should be used during osmotic dehydration to control browning in banana chips.     

Electronic implementation of the discrete Walsh transform with a variable number of data

We present an electronic system that calculates the discrete Walsh transform of a function of which any number of samples has been previously taken. In previous publications, one finds systems designed for a fixed number of samples, normally a power of two. This restriction is too great bearing in mind that no physical function is really periodical, especially in the field of biophysics, where -many important applications of this type of device are found. This makes it impossible to obtain a preset number of samples and makes the selection of sampling frequency difficult.