Agricultural Research Management Information System

Home
Research Summary
Search
About Us
- ARMIS
- Brochure
Contact Us
Report
User Request
Data Input
Help
- Operation Manual
  - PDF
  - Video
- Program Area & Commodity
We have reached 37600 number of research entries at this moment.

- Logout

Research Detail

Home
Research
Detail

Effect of Pretreatments on Drying Behavior of Eggplant

Md. Junaeid Khan
Department of Food Technology and Rural Industries, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh.

Farjana Yeasmin
Department of Agro Product Processing Technology, Jessore University of Science and Technology, Jessore-7408, Bangladesh.

Md. Nazrul Islam
Department of Food Technology and Rural Industries, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh.

Raju Ahmmed
Department of Food Technology and Rural Industries, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh.

Pabitra Chandra Das
Department of Chemical and Food Process Engineering, Rajshahi University of Engineering & Technology, Rajshahi-6204, Bangladesh.

Md. Hatem Ali
Department of Seed Science and Technology, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh.

Abstract/ Executive Summary:

Eggplant is a familiar and admired vegetable in Bangladesh. It is a highly perishable vegetable and cannot be preserved long. Drying is an ancient preservation method used to extend shelf-life of fruits and vegetables. Different Pretreatments may affect the drying kinetics of foods. A study was conducted to evaluate how pretreatments affect the drying behavior of eggplant. Proximate composition of fresh eggplant was analyzed. The samples of constant thickness (8 mm) were dried at 50°C, 55°C and 60°C to determine the effect of temperature on drying rate constant, while for determining the effect of thickness on rate constant, eggplant slices of 4, 6 and 8 mm thicknesses were dried at a constant temperature of 55°C. It was observed that, drying rate decreased with the increase in thickness and the index ‘n’ was found to be 0.89 at 55°C. Under similar drying condition at constant thickness (8 mm), drying time showed an inverse relationship with temperature. The activation energy (Ea) was calculated as 3.242 Kcal/g-mole. Eggplant slices having the highest thickness (8 mm) were blanched at 70°C, 75°C and 80°C for 1, 2 and 2.5 minutes, respectively using hot water bath to determine the effective blanching time and temperature. It was observed that the samples blanched at 75°C and 80°C for 2 minute were enough to inactivate the enzymes. Pretreated (blanched, sulphited and blanched plus sulphited) eggplant slices having constant thickness (8 mm) were dried at constant temperature of 55°C. The drying time was influenced by pretreatments. The highest drying rate was observed for eggplant slices with blanched plus sulphited (5% KMS solution) samples while eggplant slices with 5% KMS solution dipped for 10 minutes showed the lowest drying rate. In case of fresh slices, drying time was lower than blanched and sulphited samples but higher than blanched plus sulphited samples. Pretreatment was also found effective on the color changes (preservation or degradation). Blanching gave a bright color compared to fresh sample but less bright compared to sulphited samples. In case of SO₂ retention, blanched plus sulphited sample showed higher retention than sulphited sample. Sulphited sample retains 44.8 ppm SO₂/100g of sulphited sample, while the blanched plus sulphited sample retains 280 ppm SO₂/100 g of blanched plus sulphited sample.

Keywords: Pretreatment, Drying Kinetics, Eggplant

Location: Laboratories of the Department of Food Technology and Rural Industries, Bangladesh Agricultural University, Mymensingh-2202.

Start Date:

End Date:

Program Area: Postharvest and Agro-processing

Commodity: Brinjal

Objectives:

This study has been designed to determine the effects of blanching and sulphiting on ezymatic activity of eggplant and to determine the impact of pretreatments on drying behavior of eggplant.

Methodology:

The study was carried out in different laboratories of the Department of Food Technology and Rural Industries, Bangladesh Agricultural University, Mymensingh-2202. Materials and Equipment Wholesome and fresh eggplants were collected from local market of Bangladesh Agricultural University, Bangladesh. Cabinet dryer (1816, Modern Laboratory Equipment Co., Inc., New York, USA) was used for the drying operation. Chemical analysis Proximate composition and chemical analysis of fresh eggplants were done as per methods given by AOAC (2012). Sample Preparation Eggplants were visually sorted for firmness, size and absence of physical damage and finally washed thoroughly. Then the eggplants were cut into slices of 4 mm, 6 mm and 8 mm thickness using hand slicer. Pre-treatment prior to Drying Blanching: Eggplant slices of 8 mm thickness were blanched at 70°C, 75°C and 80°C for 1, 2 and 2.5 minutes respectively in a hot water bath. Blanching with Sulphitation: Blanched eggplant slices were further sulphited by dipping 5% potassium metabisulphite (KMS) solution for 5, 10 and 15 minutes. Drying Process: Cabinet dryer was used for drying operation of eggplant slices. The dryer comprised of a drying chamber in which products of known moisture content and weight were placed with trays. Hot air was blown across the trays of products being dried. The samples were dried at 50°C, 55°C and 60°C up to 5 hours to determine the effect of temperature on drying behavior of eggplant while for determining the effect of thickness on drying eggplant slices of 4, 6 and 8 mm were dried at 55°C. For determining the effect of pretreatments, pretreated eggplant slices having 8 mm thickness were dried at constant temperature of 55°C. The sample’s weights were recorded at 60 minutes intervals as well as the moisture contents of eggplant slices were determined at each time interval. Total sulphur-dioxide (SO₂) content in sulphited eggplant slices: The total SO₂ content (ppm) in sulphited eggplant slices was determined as per Ranganna (2005) using following equation:

Source of Information: J Bangladesh Agril Univ 17(1): 105–109, 2019 ISSN 1810-3030 (Print) 2408-8684 (Online)

Article Link (Online Journal): https://doi.org/10.3329/jbau.v17i1.40671

Funding Source:

1.

Budget:

Total Budget (Tk.) :

Achievement/Findings:

The study was conducted to evaluate the effect of pretreatments on the drying behavior of eggplant. Blanching or sulphitation either alone or in combination are the common pretreatments used for fruits and vegetables. Blanching inactivates enzymes that influence color, texture, flavor and nutritive quality of food products. On the other hand, SO₂ from sulphitation acts as antioxidant and prevent browning. Both pretreatments are additionally improved shelf-life of products by lessening the growth of microorganisms. In the current study, eggplant slices were subjected to blanching with or without sulphitation, while the eggplant slices without any pretreatment served as control. At constant loading density and constant temperature, lowest time is required for drying eggplant slices with blanched and sulphited (5% KMS, dipped in 15 minutes) pretreatment and was closely followed by fresh slices, while the blanched sample required the highest time when dried to constant moisture ratio (e.g. 0.1). Blanching gave a bright color than fresh sample. But, pretreatment sulphitation preserved higher color than other.

Knowledge Management: Journal