|The shelf-life studies were carried out at accelerated conditions of
38 ± 1ºC and 90 ± 2% R.H. and at standard conditions
of 27 ± 2ºC and 65 ± 2% R.H+ for the period of 4 months
and 12 months respectively for all the three selected products in different
packaging materials. Ordinary as well as gas flushing are also considered.
A) SELECTION OF PACKAGING MATERIALS :
Based on the commercial availability of packaging materials, a number of flexible packaging materials, some of which were considered suitable for gas flushing were identified and procured. The selected materials were assessed in the laboratory or basic significant physical, mechanical and physico-chemical properties. The tests conducted are with respect to the following properties :
1) Total Thickness
The results of the tests conducted on the packaging materials to assess the above properties are given in Annexure-I.
The following flexible packaging materials were selected for shelf-life studies of the specific products, depending upon the product characteristics.
(a) Dehydrated Onion Flakes
i. 12 micron PET/9 micron Al.foil/37.5 micron LDPE
(b) Dehydrated Garlic Powder
i. 12 micron PET/9 micron Al.foil/37.5 micron LDPE
(c) Accelerated Freeze-dried Corn
i. 12 micron PET/9micron Al.foil/37.5 micron LDPE
LDPE - Low Density Polythylene
B) SAMPLE DETAILS :
Dehydrated Onion Flakes and Garlic Powder were procured from one of the exporters in Mahuva near Bhavnagar and AFD Corn was procured from AFD products exporter in Baroda in a fresh condition. The samples of packaging materials were procured by the Institute and these material were converted into pouches to hold about 100 grams of the product. The pouches were packed by two different packaging systems viz. :
1) Ordinarily packed - heat sealed
All the above three products were packed into the pouches by both the
methods viz. ordinary and gas flushing.
The basic product parameters were evaluated in the laboratory on the fresh products.
1) Initial Moisture Content (IMC)
The initial moisture content of the product is the level of moisture content when the product is manufactured and packed. Samples of dehydrated Onion flakes, dehydrated garlic powder and accelerated freeze-dried corn when received in the laboratory for studies, were checked for initial moisture content by toluene distillation method for first two products and by over-drying method for third product. The initial moisture content for each selected product is given below :
Product Initial Moisture Content (IMC)
Dehydrated Onion Flakes : 6.60
2) Critical Moisture Content (CMC)
The critical moisture content of a product is the level of moisture content when the product just begin to deteriorate. The critical moisture content for each selected product was determined in the laboratory, is as given below :
Product Critical Moisture Content (CMC)
Dehydrated Onion Flakes : 8.00
The sorption Isotherm of the product indicates the behaviour of the product at different levels of relative humidity. For determining the sorption isotherm of selected products, the range of relative humidity conditions were built up in the desiccators. Each desiccator therefore shows one relative humidity ranging from 11% to 96%. Pre-weighed samples of the products were exposed to each of these relative humidity conditions. The temperature of 28 ± 2ºC was mentioned constant throughout the experiment.
The exposed product samples were weighed every 2/3 days and the change in moisture content (gain/loss) was noted. This was continued till the product achieved an equilibrium with the condition at which it was exposed. A graph of relative humidity v/s : moisture content was plotted. The ERH (Equilibrium Relative Humidity) of all 3 selected products at IMC and CMC were determined from the graph. The graphs are given in the drawing Nos. (1) – (3). The ERH for all the 3 selected products at IMC and CMC are given as below :
Product ERH at IMC ERH at CMC
Dehydrated Onion Flakes : 33.0 39.5
This indicates that the dehydrated onion flakes would pick up the moisture
when exposed to relative humidity beyond 33% and the moisture pick up
would be very rapid beyond 39.5% RH. In the case of dehydrated garlic
powder, it would pick up the moisture when exposed to relative humidity
beyond 8.1% and the moisture pick up would be very rapid beyond 23.2%
RH. Similarly the product AFD corn would pick up the moisture beyond
13.0% RH and the moisture pick up would be very rapid beyond 35% RH.
The shelf-life/storage studies were conducted on all the selected packaging
materials. About 100 grams of the product was packed. The pouches were
closed by heat sealing. Adequate number of filled pouches of all the
selected materials were exposed to accelerated conditions of 38 ± 1ºC
and 90 ± 2% R.H. and standard conditions of 27 ± 2ºC
and 65 ± 2% R.H. for a period 4 months and 12 months respectively.
During the exposure period, samples were drawn periodically from both
The packed product from these pouches was assessed in the laboratory for its keeping quality.
The parameters determined were :
1) Moisture Content
Besides assessing the product quality, the packaging materials were also observed for any changes like retention/leakage of gas from the nitrogen flushed pouches. Packaging materials were also observed visually for any changes like delamination etc.
The samples which showed deterioration earlier, were withdrawn and studies on that particular material were discontinued.
The results of the tests conducted on samples of 3 selected products
viz. dehydrated Onion flakes, dehydrated Garlic powder and accelerated
freeze-dried Corn from accelerated and standard conditions are tabulated
in Annexure-II A to VII E. Annexure-VIII, IX and X indicates shelf-life
(in days) at accelerated and standard conditions based on the storage
studies in all the selected packaging materials for dehydrated Onion
flakes, dehydrated Garlic powder and accelerated freeze-dried corn respectively.