Bundit Jarimopas

Firmness Properties of Mangoes

The purpose of this research was to determine the firmness of mango fruit at different stages of maturity. Immature, mature, and over mature fruit from two Thai mango cultivars (Nam Dokmai and Chok Anan) were subjected to two firmness measuring techniques: a slow compression technique using the Universal Testing Machine and a high-speed impact sensing technique using the low-mass impact tester. The firmness of a mango as determined by the compression test was expressed by the slope of the force-deformation graph, while firmness values derived from the impact test were defined by the ratio between maximum acceleration and the corresponding time (the firmness index). A very good correlation between the two indicators was obtained. Each firmness indicator of the two cultivars remained relatively unchanged from the immature through to the fully mature stage, although firmness rapidly decreased as the fruit ripened. The Chok Anan cultivar was firmer than the Nam Dokmai type throughout the development period. The impact method was able to determine mango firmness rapidly, accurately, and non-destructively.

Instrumentation for measuring the response of apples subjected to impact loading

Abstract Instrumentation and techniques are described for measuring and recording the force-deformation relationship of apples under impact loading. The impact force was generated by a falling pendulum in a curvilinear translation motion with undetectable friction. The device had an impact head that could be released from different positions. giving rise to velocities at the bottom of the swing ranging from 24 to 1300 m/s. Force and deformation were measured, respectively, by a piezoelectric force transducer and an electro-optical displacement follower. The signals from the two sensors were amplified and recorded on a multiple-channel analog tape recorder, connected to an X-Y plotter via a signal analyzer, to produce graphs of force or deformation with respect to time. Two such graphs of a particular sample were fed to a computer using an analog-to-digital converter to provide curves of force vs. deformation. Values of force and deformation required for the first bioyield point were 118 N and 1.52 mm, respectively. The input energy imparting the first bioyielding under impact was, on average, about 1.5 times higher than that under quasi-static loading. The described method is relatively simple, and enables obtaining reproducible unbiased results. Values of impact measured with this system compared favorably with those reported previously in the literature on horticultural products, achieved with more complicated and/or less reproducible techniques.

Postharvest Damage of Mangosteen and Quality Grading Using Mechanical and Optical Properties as Indicators

Postharvest damage in fresh mangosteens at wholesale level in Thailand was investigated from April to October 2004. A total of 37.1% of the production yield was rendered inedible by damage during this period; damages included fruit cracking, hardened rinds, rough surfaces, translucent flesh, gummosis and decay. This study focused on a method of predicting damage based on the color of the skin of the affected mangosteen. As a first step, diameter, height, weight, and volume of large, medium, small, and undersize mangosteens were measured. The term, dimension ratio, was introduced as a sizing parameter identifying conventional trade size. The coefficient of static friction of the glossy- and rough-surface mangosteens on plexiglass, plywood, and galvanized steel sheet varied from 0.31 to 0.46. The color of sound and defective fruits was measured in terms of their tristimulus values X, Y, and Z. The corresponding chromaticity coordinates of a mangosteen, x and z, depended on the maturity stage of the fruit while y depended on the type of fruit surface. A ratio was proposed to test the accuracy of predicting internal defects from the color variation between two spots on the surface of the same fruit. The highest percentage of correct prediction was 67.4% with a color ratio of X1 (pink blush color on yellow ground color) to X2 (pink color) that was greater than 1.25.

Measurement and Analysis of Vibration Levels in Commercial Truck Shipments in Thailand and Its Impact on Packaged Produce

The purpose of this study was to measure and analyze the vibration levels in commercial truck shipments in Thailand. Trucks with leaf spring suspensions are the most common logistics method to move products in South East Asia. This study measured the vibration levels in two of the most commonly used truck types used to ship packaged goods as a function of road condition and vehicle speed. The data presented in this study will assist product and package designers to reduce damage in transit by using the recommended vibration test spectrums to evaluate products and packages prior to shipment. The data can also be used by test development organizations as part of lab-simulated methods to perform preshipment tests on packaged goods. The test shipments in this study consisted of packaged tangerine fruit from orchards to retailers. The results showed that an increase in truck speed resulted in an increase in vibration levels and damage to packaged fruit. The laterite (unpaved gravel surface) road condition produced the highest vibration level for a given truck and traveling speed followed by concrete highway and asphalt road conditions. Fruit damage was found to be greatest in the uppermost container for every combination of road, truck type, and traveling speed, which also corresponded to the highest vibration levels recorded. Results of damage in packaged tangerine fruit as a function of location in the payload is also presented.

Determination of Physical, Acoustical, Mechanical, and Chemical Properties of Fresh Young Coconut Fruit for Maturity Separation

Young coconut is a popular tropical fruit featuring soft white aromatic flesh and sweet white or transparent juice. As most coconut pickers are relatively unskilled, the harvested crop tends to be distinguished by the collection of fruit of varying levels of maturity. This research has sought to improve the accuracy of grading-packaging systems by developing correlations between maturity levels and the physical, acoustical, mechanical, and chemical properties of the fruit. Results show that maturity significantly affects the specific gravity, shell rupture force, shell secant modulus, flesh penetrating force, flesh firmness, total soluble solids, titratable acidity, flesh thickness (FT), and natural frequency of young coconut at p

Mechanical and Light Properties of Mangosteen Fruit as Related to Postharvest Quality

During this study the postharvest damages of fresh mangosteen at wholesale level in Thailand were investigated from April to October 2004. Damages included fruit cracking, hard rind, rough surface, translucent flesh, gummosis, and decay. Total percentage of all damages that made fruit inedible was 43.3 % of production yield. Weight, volume, and dimension of large, medium, small, and undersized mangosteens were measured. The term of dimension ratio was introduced as a sizing parameter compared to the conventional trade parameter. The coefficient of static friction was also determined. This coefficient for gloss and rough surface mangosteens on plexiglass, plywood, and galvanized iron steel varied from 0.31 to 0.46. Color of sound and defective fruits was measured in terms of tristimulus values, X, Y, and Z. It was observed that the corresponding chromaticity coordinates, x and z for mangosteens depend on their maturity stage while y depends on the type of fruit surface. A color ratio term is proposed to be used as a nondestructive technique for detecting internal defects of mangosteens. The highest percentage of correct prediction was found at the color ratio X1/X2> 1.25 at 67.4 %