Guide to Inspections of Low Acid Canned Food 6
time/temperature of blanching, post blanching product temperature, time held prior to processing, and the firms procedures for cleaning the blanching equipment.
Product formulation must be evaluated during inspection of lacf manufacturers to determine if formulation changes have been made. Changes in starches, gums, sugars and other thickening agents from those used to establish the thermal process can have a dramatic effect on the thermal heating characteristics of the product. Management at the processing facility should be able to document the formulation upon which the process was established and to provide the current formulation. Failure of the firm to provide formulas for evaluation may lead to requests from FDA's CFSAN, through the firm, to the processing authority of record to supply the requested information.
Starches have a wide range of heating and setting characteristics, the science of which is called starch rheology. The temperature at which different starches set (become thick) can vary over a wide temperature range. Some starches may set upon heating while other starches set upon cooling. Some starches may set rapidly within narrow temperature ranges while others thicken over a longer time period. Changing the starch used in the formula (even from one brand to another) may change the heating characteristic of the product. Small changes in the amount of starch used (i.e. 1% to 2%) can have a dramatic effect on the thermal heating of the product. For this reason formulations containing starch should be strictly controlled.
Rehydration of dry ingredients, such as beans, rice, peas and potatoes, can have a thickening effect on the formulated product. This may change the heating characteristics of the product and may be especially important in agitated products. Adequate rehydration of dry and dehydrated raw materials such as beans and peas prior to the thermal process may be critical to the process. Beans and peas are normally rehydrated by soaking the beans and peas in water soak tanks for a specified time or until they obtain a predetermined soak weight. Dry beans may vary from 18% to 9% moisture. The lower the moisture the longer the soak time. For an adequate soak 100 lbs of dry beans will typically supply 185 to 190 lbs of soaked beans. The covering liquid or sauce may have to be varied to account for the water which will be absorbed during processing and storage. If the dry product is not adequately rehydrated excess moisture may be drawn from the covering liquid or sauce during processing and the bean/pea may expand to fill the headspace. This may inhibit or prevent product agitation if agitating processes are used. Rehydration of dry beans/peas is normally considered to be a factor critical to the thermal processing of dried bean/pea products. In most cases this will be listed as a critical factor on the filed scheduled thermal process. If rehydration of dried beans/peas is not controlled as a factor critical to the thermal process this should be discussed with management at the lacf facility. Other dry or dehydrated raw materials may exhibit similar effects on the scheduled thermal process.
Product formulations should be reviewed to determine if the firm has changed the form of the ingredient (e.g. from fresh or frozen ingredients to dehydrated ingredients), or if the varieties of the ingredients have been changed (different varieties may have different rehydration properties).
During inspection of lacf manufacturers producing formulated products using dry ingredients the firms procedures for ensuring that all dry ingredients are adequately mixed into the formulation should be determined. Firms using hydrolyzed vegetable protein in formulated products have experienced problems with the vegetable protein matter clumping in the product, forming dry product clumps which prevented adequate thermal heating of the product. Although this has not been documented, the same type of clumping could occur with other dry products that are not adequately mixed into the liquid portion of the product.
The lacf regulations, 21 CFR Part 113.81 (e), provide for acids to be added to lacf products to reduce the pH of the product to a level which is still above 4.6 but at a level which aids in the destruction of microorganisms. This can result in thermal processes which provide a safe product with a reduced thermal process time and/or temperature. These types of processes are normally designed to provide for the thermal processing of lacf foods which would be destroyed by a normal thermal process; or to provide thermal processes for foods to gain what is perceived to be a better quality product with less loss of nutrients. Where the addition of acids are used in conjunction with the thermal process, there is a need for careful control and monitoring of the pH of the product during production as well as the equilibrium pH of the product. The firms production records must reflect that the pH is being controlled. Procedures used for determining the pH of acidified low-acid canned foods may be followed.
The lacf regulations 21 CFR Part 113.81(f) provides for control of the growth of microorganisms not destroyed by the thermal process through the control of the equilibrium water activity (aw) of the