Proceeding of 2013 International Seminar on Climate Change and Food Security ISCCFS 2013
Palembang, South Sumatra -Indonesia, 24-25 October,2013
164 lemon grass and salt, and alternatively
tempoyak
to produce
pepes tempoyak
.
Tempoyak
is a fermented durian product
[12]
.
2.2. Food Cooking by Microwave Oven
The heating of foods by microwave energy is accomplished both by the absortion of microwave energy by dipolar water molecules and ionic components of the food. Thus, both the water content and the
dissolved ion content often salt are dominating factors in the microwave heating of foods. When the dipolar water molecule is subjected to a microwave field, with the field rapidly changing its direction, the dipole
tries to align itself with the field direction. There is a time lag, as some response time is required for the water molecule to overcome the inertia and the intermolecular forces in the water. The electric field thus
provides energy for the water molecule to rotate into alignment. The energy is then lost to the random thermal motion of the water and results in a temperature rise. When ionized compounds are subjected to a
microwave field, they randomly collide with nonionized groups in an electric field. The kinetic energy of these ions is transmitted into heat during the collisions
[13]
. Temperature distribution in cooking using microwaves may not be uniform. Consequently, food could
not be cooked uniformly
[14]
. The measurement of food temperature at several parts was important in order to confirm that the food temperature has reached recommended temperature sufficient to kill pathogenic
microbes. In other words, cooked fish should reach 145 °F
[15]
. Measurements of fish temperature can be carried out in several parts based on consideration of the difference in thickness. When the shape of food is
irregular, the thinner and the narrower parts tend to be hot more rapidly in microwave cooking
[16]
.
3. Materials and Method
3.1. Experiments and materials preparation
Fresh nile tilapia
Oreochromis niloticus
250g ± 20 in weight, tamarind, shallot, garlic, red chilli, salt, sugar, ginger, candlenut, turmeric, galangal, lemon grass and banana leaves were purchased from local
traditional market in Palembang, South Sumatera. The materials were brought to WSTPHP Workshop Teknologi Pengolahan Hasil Perikanan of The Fishery Faculty of University of PGRI Palembang in
Palembang South Sumatra. Fresh fish were eviscerated, descaled and then washed with tap water. Raw
pepes
was prepared according to a modified method of Diana et al. 2010
[1]
with a slight modification, namely unit conversion of material from piece to weight weighted, and the use of tamarind juice and refined sugar
to improve flavor of
pepes
. The following equipments were used in this research, including commercial microwave oven Sharp model R-2491NW, 2450 MHz, 800 W, pot steamer, thermometer insertion
digital thermometer Krisbow KW06-308, temperature range -40°C to 250°C and other equipments for microbial analysis. The research was conducted from January 2013 to March 2013.
One factor was investigated in this research, namely cooking time of
pepes
with microwave oven and consisted of three following levels: 4 A
1
, 5 A
2
and 6 minutes A
3
with three replications. In addition,
pepes
was heated in microwave oven for additional 3 minutes before removed. The observed parameters were total plate count TPC, internal temperature and visual observation. TPC analysis was conducted at
LPPMHP Laboratorium Pembinaan dan Pengujian Mutu Hasil Perikanan Palembang in Palembang South Sumatra, whereas internal temperature measurement and visual observation were conducted at WSTPHP
Workshop Teknologi Pengolahan Hasil Perikanan of The Fishery Faculty of University of PGRI Palembang in South Sumatra.
3.2. Samples Analysis 3.2.1. Microbial content TPC
