Factors Affecting The Suitability Of Glass Jars For Heating In Microwave Ovens. Comparison With Plastic Jars & Paper Board Tubs

The suitability of glass jars for heating in microwave ovens was studied, with the aim to determine the effects of the type of foodstuff, the shape & volume of the jars & the heating conditions (eg type of microwave oven & initial temp) on the functionality & durability of glass jars heated in microwave ovens & on the heating result. The behaviour of glass jars was compared with that of paperboard & plastic containers. A total of 243 glass jars were heated during the the tests. None of the jars were broken, even when the contents were initially frozen or when all the jars were placed on a cold surface immediately after heating. However, splashing of the contents and/or jumping of the jar with a resulting loud clatter was a problem. Jumping & splashing of contents depended on both recipe & consistency of food & shape of jar, but less on the packaging material. the initial temperature or the heating time. The plastic and board containers also jumped and food splashed out of them. If glass jars or cylindrical/jar-like packages are to be used for the packaging of microwaveable foods, both the recipe of the foodstuffs and the shape of the jars need to be developed further.