Development and Evaluation of an Audio System Trainer

Guided by the desire to contribute a little in the development of an innovative instructional technology for the teaching of electronics, this researcher constructed a prototype audio system trainer. Electronics teachers will find the instructional tool convenient and practical to use for visual instruction, laboratory activities and troubleshooting works in electronics. To support the functionality of the audio system trainer, the researcher developed a supplementary laboratory manual. The project whose production costs totaled fourteen thousand two hundred seventy two pesos and fifty centavos (Php 14,272.50) was finished in two weeks’ time. However, this amount is small if compared to the prices of commercially available instructional device developed for the same purpose. The completed project and the supplementary laboratory exercises were evaluated by selected technical faculty members of the College of Industrial Technology of the Bulacan State University, Bulacan Polytechnic College, University of Rizal System, and Lyceum of the Philippines University. Sampling technique as used in the study is both purposive and incidental. The prototype audio system trainer received an over-all mean rating of 4.62 which means that the project is highly acceptable on a set of criteria which includes – physical features, cost, function / operations, and durability. Furthermore, the supplementary laboratory exercises obtained a mean of 4.70 which could be interpreted that the respondents strongly agree on the validity of the manual.

Storage Performance and Amelioration of Chilling Injury in Mango Fruit

A series of experiments was conducted to evaluate the storage performance and chilling sensitivity of mango cv. “Langra” fruit and various remedial measures were investigated to extend the storage life of mango fruit by enhancing chilling tolerance. Mango fruits were stored at 5, 10 or 15 ± 1 °C for 0, 5, 10, 15, 20, 25 or 30 days and evaluated for various physico-chemical attributes and chilling injury. Fruit firmness, titratable acidity, non-reducing sugars and ascorbic acid decreased with the increase in storage temperature and duration. Chilling injury was the highest at the lowest temperature (5 ± 1 °C) and maximum storage duration (30 days). The ion leakage was the least in fruits stored at 10 ± 1 °C and the highest at 15 ± 1 °C and increased with the increase in storage duration. Evaluation of fruits stored for 5, 10, 15, 20, 25 or 30 days at 5, 10 or 15 ± 1 °C after 3 days simulated markting revealed that weight loss, fruit firmness, chilling injury score, titratable acidity, ascorbic acid and non-reducing sugars were the highest in fruits exposed to 5 ± 1 °C before simulation. After simulated marketing, weight loss was initially lower in fruits exposed to 5 ± 1°C but with the increase in storage duration it got higher than the remaining temperatures. The mean ascorbic acid was the highest at 5 ± 1°C after 3 days simulated marketing however, the interaction of storage durations and temperatures revealed rapid decrease in fruit stored for 25 or 30 days at the same temperature. The fruit juice pH and reducing sugars were higher in fruits stored at higher temperature, while the least ion leakage and highest total soluble solids (TSS were in fruits stored at 10 ± 1°C before simulated marketing. While weight loss, chilling injury score, fruit juice pH, ion leakage and reducing sugars increased, the fruit firmness, titratable acidity, ascorbic acid and non-reducing sugars decreased after 3 days simulated marketing. The TSS initially increased and then decreased with the increase in storage duration. To reduce chilling injury, mango fruits of cv. “Langra”, were treated with methyl jasmonate (10−4 M), methyl salicylate (0.1mM), acetic acid (4 ml L-1), 1- MCP (2 μL L-1) and ethanol (0.5 M) and stored for10, 20 and 30 days at 5 ± 1 °C. The physical and chemical attributes were evaliauted on day “0”, after completion of the respective cold storage duration and after 3 days simulated marketing. Weight loss, chilling injury score and ion leakage were the highest in control and the least in fruits treated with methyl jasmonate. Treatment of fruits with 1-MCP maintained the maximum firmness, titratable acidity, ascorbic acid and non-reducing sugars, whereas the highest TSS, fruit juice pH and reducing sugars during cold storage and simulated marketing were with methyl jasmonate. The TSS increased continuously with the storage and after simulated marketing in fruits treated with 1-MCP but declined after simulated marketing with rest of the treatments. To optimize the heat treatments and subsequent incubation for inducing chilling tolerance, mango fruits were exposed to heat shock at 45 ± 0.5 °C for 0, 2, 4 or 6 hours and then incubated for 0, 3 or 6 hours before storage at 5 ± 1 °C for 30 days with an additional 3 days simulated marketing. These fruits were evaluated for physico-chemical quality attributes and chilling sensitivity after cold storage and simulated marketing. The minimum mean weight loss, chilling injury score and ion leakage, while the maximum fruit firmness, titratable acidity, reducing sugars, non-reducing sugars and ascorbic acid after cold storage and simulated marketing, were recorded with 2 hours heat shock treatment. The means for incubation time revealed the minimum weight loss, pH, chilling injury score and ion leakage while the highest fruit firmness, TSS, titratable acidity, ascorbic acid and reducing and non-reducing sugars in fruits incubated for 3 hours. To evaluate the influence of cold shock durations and incubation times on quality attributes and chilling sensitivity, mango fruits were treated at 0 °C for 0, 2, 4 or 6 hours and then incubated for 0, 3 or 6 hours before storage at 5 ± 1 °C for 30 days with an additional 3 days simulated marketing time. The mean for cold shock duration showed the minimum weight loss, chilling injury score, ion leakage and fruit juice pH in fruits treated with cold shock for 4 hours that were statistically at par with 6 hours. The incubation time of 6 hours resulted in the least chilling injury score, ion leakage and fruit juice pH both during storage and simulated marketing. Similarly, the highest fruit firmness, titratable acidity, ascorbic acid, reducing and non-reducing sugars were in 4 hours cold shock treatment. Ascorbic acid was the maximum during storage in fruits incubated for 3 hours and with 6 hours after simulated marketing. It is concluded from the overall project that mango cv. “Langra” fruits can be stored for 30 days at 5 ± 1 °C, when treated with methyl jasmonate or 1-MCP. Physical treatments such as heat shock (45 ± 0.5 °C for 2 hours + 3 hours incubation) or cold shock (4 hours at 0 °C + 6 hours incubation) are equally effective in reducing chilling injury and retaining mango fruit quality during cold storage and 3 days simulated marketing.