How Do You Define Product Degradation?

Solids handling problems in food manufacturing can take on many forms. The classic solids handling problems that may first come to mind are those that prevent controlled discharge: arching, ratholing and flooding. However, other solids handling problems can have a significant impact on product quality. One such problem is broadly described as product degradation.

Degradation is the undesirable change of a product or ingredient. It can take many forms in food products, including moisture absorption, caking, microbial growth, or breakage. These undesirable changes often lead to non-uniformity, resulting in lost revenue caused by rework, scrapped product, or downgrading of products. They can also lead to customer complaints and loss of market share.

Product degradation can occur at any number of points in a food manufacturing process, but a common area that is frequently overlooked is storage or surge bins and their associated feeders or dischargers. Proper design of this equipment, and integrating the design of the two functions (storage and discharge), is essential in protecting your food product against degradation. A properly designed storage and discharge system must provide a first-in, first-out flow sequence, it must allow for interparticle motion during flow, and it must limit the forces that may act to break friable products.

A first-in, first-out flow sequence ensures that no stagnant regions exist during discharge. This is normally an important aspect of storage of a product or ingredient for inventory management, since it ensures that inventory is turned over regularly rather than aging in a silo. Stagnant regions in a silo may occur, even during discharge. If this occurs, loss of inventory control will result, with microbial growth and caking being potential outcomes, depending on the material properties and storage conditions.

Sugar and salt are two materials that are particularly difficult to store in large silos since both are prone to caking when exposed to moisture or temperature gradients that drive moisture migration. This tendency to cake is often made worse by grinding or even by attrition that may occur inadvertently, such as during pneumatic conveying.

Many food products are susceptible to some form of microbial growth or spoilage during storage. This is particularly true for in-process materials that may not be as shelf-stable as finished products. Because of this, eliminating stagnant material and providing a first-in, first-out flow sequence are particularly important in most food processing applications.

Jenike & Johanson can test your ingredients and products and recommend appropriate hopper geometry and wall surface finishes to prevent stagnant regions during discharge and to ensure a first-in, first-out flow sequence.