There are number of methods for preservation of breads from spoilage and microbial degradation. These methods includes:
Prevention of microbial contamination
It is first and foremost consideration in raw materials for bread during the bread production. They should be kept properly so that none of spoilage causing organisms can/ could affect the products.
Organisms like bacteria especially Bacillus, yeasts and molds (Penicillium and Rhizopus) are normally present in breads. During baking almost 82-90% of bacteria are killed. Microbial contamination can be prevented by using flour free of microorganisms.
Uses of preservatives
Preservatives are substance or a chemical added to products such as food, beverages, drugs etc. to prevent decomposition by microbial growth or undesirable chemical changes.
Number of artificial preservatives are used in bread. Calcium propanoate and propionic acid are commonly used. More calcium propanoate in loaf is often referred as more calcium in bread. Propionic acid inhibits growth of bacteria in food, thereby extending its shelf life.
Natural preservatives in breads are lecithin, ascorbic acid, cinnamon oils etc. Lecithin comes from soy or egg yolks which keeps bread fluffy and light. Ascorbic acid (Used in bread as powdered form) reduces growth of microorganisms and helps yeast to rise faster. Cinnamon oil inhibits rising of yeast and therefore, lessens breeding ground for microorganisms.
Use of modified atmospheric packaging
Breads cooled and packed in perfectly sterile condition are free from microbial contamination hence no molds and bacteria will appear in the products. Besides this, additional precautions are taken under modified atmosphere packaging. By using this technology very little or no oxygen remains in the packet and no molds will grow because most molds and bacteria requires oxygen to grow.
To achieve this process successfully following conditions has to be fulfilled:
- The room in which bread is cooled and packed have to be kept as sterile as possible (clean room technology). Working personnel in this area need to follow set of strict rules to keep the room clean. Outdoor air can’t enter the room or air entering has to be filtered using absolute filter so no microorganisms can enter through air.
- Packaging materials need to have a barrier from oxygen so outside air can’t enter the packet but it must also create a barrier from gases inside the packet so that they cannot escape. Normally nitrogen and carbon dioxide are used as gas procedure.
Freezing / drying
Freezing limits or inhibits growth of organisms that can cause food spoilage. Freezing breads is by far the best way to preserve it. Freezing greatly slows down staling process, and reheating the bread in an oven or toaster re-gelatinizes the starch and makes bread springy and chewy again.
Drying is a natural technique for preventing spoilage. Common methods of drying are sun drying, vacuum drying, drum drying, heated air drying. Heated air drying and vacuum drying are most commonly used for bread preservation.
It is an alternative method to be used instead of chemical preservatives with an aim to produce bread without addition of preservatives. Breads after baking and packaging is heated to certain temperature for certain time so, all microorganisms are killed. This can be done in hot air oven and microwave.
Download Link: Methods of Bread Preservation.pdf