Microwave-assisted hot air drying for Phulae pineapple and its effect on quality changes during storage

Name: Mamba, Senteni Babongile

Address: 333 Moo1, Thasud, Muang, Chiang Rai 57100

Organization : Mae Fah Luang University. School of Agro-Industry. Food Science and Technology

Email : ask.library@mfu.ac.th

keyword: Phulae pineapple

LCSH: Food -- Drying

Classification :.LCCS: TP371.6 M263m 2019

LCSH: Pineapple -- Thailand

LCSH: Pineapple industry

LCSH: Dried foods

LCSH: Pineapple -- Processing

Abstract: Drying is the most famous method used in ‘Phulae’ pineapple processing to solve the overproduction problem of fresh fruit. Long-time of hot air (HA) drying or sun drying results in undesirable quality changes of the dehydrated product. The aim of this study was to investigate the suitable condition in microwave-assisted hot air drying (MAHD) of ‘Phulae’ pineapple within a short time, as well as to observe the quality changes during storage at room temperature in comparison to HA dehydrated sample. The results showed that varying hot air temperature, turning on and off magnetron, as well as rotating the samples in the chambers (A, B and C) reduced the drying time and ensured uniform drying of samples in all the chambers. The suitable condition was drying with microwave and hot air at 75 ºC for 160 minutes, followed by reduction of temperature to 45 ºC for 80 minutes and finally turned off magnetron and dried with hot air only at 70 ºC for 60 minutes. The samples in each chamber were rotated every 80 minutes from the beginning until the end of application of microwave. Samples rotation help to prevent burning of samples and ensure same drying time in the 3 chambers, which usually result from the different heating rates in the different chambers. This condition could reduce the overall drying time from the previous study as seven hours to five hours. MAHD dehydrated sample had high total phenolic (TPC) content of 0.14 to 0.42 g 100 g-1 GAE DW, antioxidant acitvity measured by Ferric reducing atioxidant power (FRAP) was in the range of 113 to 174 mM g-1 DW and Diphenyl-1-picryl hydrate (DPPH) values ranged from 28.25 to 32.72 mM TE 100 g-1 DW as well as a high vitamin C content of 4.15 to 4.19 mg 100 g-1 DW. The TPC of HA dehydrated sample was in the range of 0.11 to 0.32 g 100 g-1 GAE DW, antioxidant activity measured by FRAP assay ranged from 90.73 to 120.36 mM g-1 DW, 25.23 to 31.88 mM TE 100 g-1 DW for DPPH and vitamin C content was in the range of 3.38 to 3.45 mg 100 g-1 DW. High toughness values were recorded in MAHD sample (88.84 to 144.78 N) in comparison to HA dehydrated sample (70.48 to 72.12 N). Upon physical observation, the appearance of the sample at the end of the 60-days storage period was better in MAHD when compared to HA dehydrated sample, because MAHD sample had a small amount of moisture gain during the storage period when compared to HA dehydrated sample. When it comes to microbial safety, samples from both drying techniques were safe throughout the storage period as the maximum microbial load recorded in HA sample was 2.93 log CFU g-1 in yeast and mold and 3.45 log CFU g-1 in total bacterial count. MAHD sample, on the other hand, had a maximum of 2.71 log CFU g-1 in yeast and mold and 2.63 log CFU g-1 in total bacterial count. Water activity (aw) ranged from 0.52 to 0.68 in HA dehydrated sample, while MAHD sample ranged from 0.50 to 0.61 during the 60-days storage period. Moisture content was in the range of 16.55 to 17.49% in HA and 14.66 to 16.26 % in MAHD. The shelf life of HA dehydrated sample was predicted to be 92 days while MAHD samples had a predicted shelf life of 125 days, based on 18 % moisture content which is the maximum amount expected in a dehydrated product.

Mae Fah Luang University. Learning Resources and Educational Media Center

Address: CHIANG RAI

Email: library@mfu.ac.th

Name: Phunsiri Suthiluk

Role: Advisor

Email : ask.library@mfu.ac.th

Name: Nattaya Konsue

Role: Co-Advisor

Email : ask.library@mfu.ac.th

Created: 2019

Issued: 2563

Modified: 2020-05-14

Issued: 2020-03-03

วิทยานิพนธ์/Thesis

application/pdf

CallNumber: Thesis TP371.6 M263m 2019

eng

DegreeName: Master of Science

Level: Master's Degree

Grantor: Mae Fah Luang University

Descipline: Food Science and Technology

©copyrights Mae Fah Luang University

ลำดับที่.	ชื่อแฟ้มข้อมูล	ขนาดแฟ้มข้อมูล	จำนวนเข้าถึง	วัน-เวลาเข้าถึงล่าสุด
1	129590.pdf	3.69 MB	8	2025-09-10 14:14:57

ใช้เวลา

0.030373 วินาที