Recommended Energy Studies in the Food Processing and Packaging Industry: Identifying Opportunities for Conservation and Efficiency

Introduction

The food processing industry provides approximately 93% of the food purchased by wholesale suppliers and about 60% of the food consumed by U.S. households (Connor & Schiek, 1997). Although the energy usage (2.6% of the 1992 shipments value) in the canning industry is not as high as in processes such as corn milling operations, the energy usage (2.6% of the 1992 shipments value) is significant and worthy of study for improvements in efficiency and savings. Extension professionals, consultants, and food processors can work together in these energy studies to prevent potential critical energy shortages in the future.

The cost of energy is a significant part of the total cost of processing foods, especially at the unit operations level, such as in pasteurizing or commercial sterilization (thermal processing) of foods, where various forms of energy may be used. Heating and cooling are two unit operations where energy consumption is critical. Heating is particularly important due to the requirements of having steam at different temperatures and pressures to achieve acceptable food safety levels.

When considering opportunities for energy efficiency and savings in the food processing industry, food safety is the most important factor, and it cannot be compromised. For example, in canning, an adequate supply of energy by steam or hot water is necessary to obtain the right temperature during the process time in order to achieve commercial sterility.

Optimizing energy use and efficiency can be accomplished by energy audits. However, these audits require data, information, and educational materials that are not readily available to the food processor. Several factors make energy assessments difficult. For example, a canned product requires unit operations such as heating, cooling, mixing, pumping, and packaging (Singh & Heldman, 1993; Lopez, 1981). In addition, various forms of energy may be used, including steam, electricity, gas, or fuels (Figure 1). Team efforts between industry professionals and universities can achieve the development of energy audits to fulfill the need of energy efficiency and cost savings.

Objectives

The following are recommended objectives to any parties interested in studying energy in the small food processing industry.

1. To study energy usage by representative small or medium size processing plants.
2. To identify critical areas and factors to improve the efficiency of selected processing systems.
3. To develop model energy audit questions that small and medium food processing companies can use for self-auditing and energy assessment.
4. To develop educational materials (manuals, videotapes, CD¹s, etc.) about Energy Conservation and Efficiency for the food processing industries.
5. To provide training workshops about energy conservation and efficiency for the food industry.
6. To develop educational materials to be used in "Train the Trainer" workshops.
7. To use the existing Extension Service network through land-grant universities to transfer the generated knowledge.

Recommended Methodology

1. Proposals should address the energy consumption in selected food processing plants by calculating the total energy consumed expressed in an equivalent energy unit per pound of product on at least a 6-month or 12-month basis. All energy inputs will be included and converted to a selected equivalent basis (Nelson, 1994).
2. The total energy usage should be compared to the energy consumed by individual unit operations (Figure 1) in a selected process or processes. The ideal selected plant should consider only one type of food at a time, in order for the energy account to be balanced. Each unit operation will be ranked by the amount of energy consumed. Factors affecting energy efficiency should be studied and identified, including the energy used by non-processing equipment. Appropriate computer software packages could be used for monitoring, measurements, and accounting purposes.

   
   Figure 1 - Typical commercial canning operations indicating common sources of energy in each operation.

3. The main tool to perform the energy and material balances is the development of a process flow diagram, known in engineering practice as the "Process Flow Sheet." This flow sheet in its final and detailed form represents a blueprint for processing, energy savings, and general improvements (Ulrich, 1984). A general model flow sheet should be developed for use by small companies.
4. An energy audit form to be used in small plants should be developed based on general principles extracted by the energy study. The interested parties should also develop educational materials as the energy study is performed.
5. It is also recommended that training workshops be developed and delivered once the educational materials are completed.

Potential Collaboration

Currently, the Food Science and Human Nutrition department at Clemson University, through the Cooperative Extension Service, is seeking opportunities to work with other land-grant universities, small food processors, canneries, and other professionals willing to participate in this kind of study to collect data, analyze results, and implement workshop recommendations.

References

Conner, J. M., & Schiek, W. A. (1997). Food processing: An industrial powerhouse in transition (2nd ed.). New York: John Wiley and Sons, Inc.

Lopez, A. (1981). A complete course in canning; Book 1, basic information on canning (11th ed.). Baltimore: The Canning Trade, Inc.

Nelson, K. E. (1994, Sept.). A practical guide to energy. Chemical Engineering. 122-128.

Singh, R. P., & Heldman, D. R. (1993). Introduction to Food Engineering. (2nd ed.). London: Academic Press, Inc.

Ulrich, G. D. (1984). A guide to chemical engineering process design and economics. New York: John Wiley and Sons, Inc.