Pudding cups should be constructed from materials that can act as a strong barrier to oxygen to extend their shelf life. This article explores the use of oxygen transmission rate testing, via a coulometric method, to test how effective a pudding cup is as an oxygen barrier.
This article will explore the testing method and the instrumentation needed with associated specifications and can be used as a reference for oxygen permeability tests on different types of packaging.
Packaging in the shape of a cup is used to store puddings as it holds the pudding in its required shape and protects it from being damaged and deformed during storage and transportation.
The main ingredients in pudding, namely dairy products, eggs and fruit juices, are all prone to oxidation. If these components are oxidized the pudding will lose its taste and nutritional value. To prevent this from happening the packaging used should have a low oxygen permeability.
The majority of pudding cups are produced from plastic or glass, with plastic cups being the more popular option as they are easier to transport. There is a lot of variability in the permeability of different plastics, and even when using the same plastic differences in processing and/or material thickness can result in differences in permeability.
Due to the extent of this variability it is important that accurate oxygen transmission rate (OTR) measurements are taken of each packaging material for quality control purposes.
Figure 1. Pudding Cups
Sample to be Tested
One sample of plastic pudding cup was tested to evaluate its OTR.
Two different methods are available for the testing of the OTR of packaging. These are the coulometric (equal pressure) method and the differential pressure method.
The test used in this article followed ASTM F1307-02: Standard Test Method for Oxygen Transmission Rate through Dry Packages Using a Coulometric Sensor.
Testing was carried out using Labthink Instrument’s C230H Oxygen Transmission Rate Test System.
Figure 2. C230H Oxygen Transmission Rate Test System
The testing takes place over two different stages – permeation and detection.
The permeation step involves injecting oxygen and nitrogen (of equal pressure) into the space surrounding the sample and the space inside the sample. Following the concentration gradient oxygen will permeate through the sample into the nitrogen filled interior.
The movement of the oxygen generates an electrical signal in the coulometric sensor, and this signal can be used to determine the OTR.
The test range for film/sheeting is 0.01 ~ 200 cm3/(m2·day). The test range for package is 0.00005 ~ 1 cm3/(pkg·day), with the resolution of 0.001 cm3/(m2·day). The repeatability is 0.01 cm3/(m2·day) or 2%. The internal humidity and temperature of the instrument are automatically adjusted with temperature and humidity sensors, maintaining the stability of the test specimen environment.
The test temperature range is (10±0.2) ℃ ~ (55±0.2) ℃. The test humidity range is 0%RH, (5±1) %RH~ (90±1) %RH and 100%RH. Three identical or distinct specimens can be tested concurrently. The specimen size is 108 mm × 108 mm. The test area is 50 cm2.
Unique DataShieldTM system (optional), meets the requirements for centralized management of user data. It supports a variety of formats of exported data. Reliable security algorithms are utilized to avoid data leakage. It supports universal wired and wireless LAN, optional private wireless network, and supports third-party software.
(1) The instrument is applicable to determining the OTR of various plastic films, paper, plastic composite films, co-extruded films, aluminum plastic composite films, aluminum coated films, sheeting of PP, PVC, PVDC, metal sheet, silicon wafers, rubber sheet, wine bottles, bottles, peanut oil bucket, vacuum packaging bag, tetra pak, three-piece metal can, plastic cosmetic package, toothpaste tubes, jelly cups, and yogurt cups.
(2) The instrument can be used to test the oxygen barrier property of sealing lid, solar panel sheet, pipes, automotive fuel tanks, medical blister pack and battery shell, etc.
(3) The instrument conforms to a range of Chinese and international standards including GB/T 19789, GB/T 31354, ASTM F1307, ASTM D3985, ASTM F1927, DIN 53380-3, JIS K7126-2-B and YBB 00082003.
- The sample to be tested should be sealed into the fixture using a fast-acting adhesive. Once the sample is secured the fixture should be mounted on the instrumented and sealed using a sealing bag. The temperature can be controlled using the package hood.
- Test parameters, including sample name, test temperature and humidity, and more should be set; following this the test can be ran.
- Testing is ran automatically with the temperature and humidity held constant.
- Following testing the results are displayed on the system.
Testing found that the OTR of the sample was 0.56315 cm3/(pkg·day).
How permeable the packaging of a pudding cup is towards oxygen determines the rate at which the pudding will be oxidized, which has a direct impact on the pudding’s shelf life.
This article explored using an OTR test, following a coulometric (equal pressure) protocol, to determine how appropriate packaging is for use in a pudding cup.
This information has been sourced, reviewed and adapted from materials provided by Labthink International, Inc.
For more information on this source, please visit Labthink International, Inc.