Purpose: The objective of this study was to evaluate and compare vacuum levels, sealing rates and retention of food quality with three home canning lid systems (metal, plastic and glass) at 24 h and through 3 months storage.
Methods: Three foods (tomatoes, apples and carrots) were canned in three lid systems. Foods chosen represent two processing temperature requirements (100 and 115.6°C) and different stressors to lid performance. Lids were subjected to four application treatments (recommended, unwiped sealing surface, overfilled jars and a combination of unwiped and overfilled). Each lid, food and treatment combination was replicated 12 times resulting in 576 jars processed. A total of 192 of each lid type was used; 160 jars of each lid type were analyzed for this study at 24 h, 10 d, 1 mo or 3 mo.
Results: Through 3 mo storage, all three lid types had acceptable sealing rates and initial vacuum levels (13 - 18 in Hg for boiling water and 18 - 24 in Hg for pressure processed foods) in jars not overfilled. All jars sealed at 24 h. A total of 6 seal failures occurred during the storage period of this study; four were plastic lids and two were glass lids.
Significance: Food quality and successful thermal processing are influenced by the quality of the vacuum seal, as is protection of the economic investment in home food processing. Recommendations for home canning should be based on sound thermal processing advice well as scientific evidence for reliable containers and seals. Excessive air retention in jars can lead to sealing issues and possible microbial spoilage.