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Whether as a guest from the outside, as a consultant, or as an employee from headquarters or another site, touring a food plant is an opportunity to be taken seriously and seized as a teaching moment. Common sense and good manners dictate that you introduce yourself to your host and to others you may meet. Each plant may have its own safety and sanitation requirements, but most will require that a visitor take off jewelry (except simple wedding bands, usually) and wear a distinctive badge, clean smock, hair net (and beard net, if necessary), closed-toe shoes, and ear plugs or other hearing protection. In some plants, hard hats may be required, and some issue rubber boots.
Usually, there is a briefing in which the purpose of the visit is discussed and an overall description of operations may be given. It is common to tour in the same direction that materials flow, from receiving raw materials to shipping finished goods. Some portions of a plant may be considered so proprietary that an ordinary visitor may be excluded from those areas. In other plants, where allergens may be processed, visitors may be excluded from certain spaces to prevent cross-contamination.
So, subject to the usual restrictions, what should you look for?
How and where are ingredients delivered and stored? What are they? Are they inspected on receipt? Are they segregated until approved? What happens to rejects? The same questions apply for finished goods, when you get there. How and where are packaging materials received and stored? How are ingredients and packaging materials delivered to lines?
If the hoppers holding powders or particulate materials are dented from being hit to induce flow, you can safely conclude there are or have been serious material handling problems. These are often opportunities to make a constructive contribution, if that is your role.
Note the major methods of moving material around the plant. Some common ones include:
• Pneumatic conveying for solids (pressure or vacuum)
• Fork trucks for pallets, drums, and bags
• Intermediate bulk containers (totes, big bags, etc.)
• Conveyor belts for containers, cases, and some foods
• Conveyor chains for cans and other containers
• Bucket elevators
• Screw conveyors
• Freight and personnel elevators
• Pipes, often stainless steel tubing, for liquids, gases, and utilities
• Drains in the floor for wastewater, which should be stainless steel in process areas; may be trench or hubs (round or square); floors should slope to drain
• Ducts for supply and removal of heated or cooled air
• Hoods for dust collection
Note the provisions for electric power, control wiring, lighting, and security. Are wires contained in metal conduit, in cable trays, or loose? Is the conduit mounted away from the walls to allow cleaning behind it? Is the conduit neatly installed?
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Other Sanitary Design Features
Normally, a visitor is not expected to be critical or conduct an audit, unless that is the purpose of the visit. However, the knowledgeable visitor notes conditions and forms an opinion, which may or may not be later shared.
The overall morale and management style may be portrayed in the cleanliness and neatness of a plant. A food plant should be clean, with minimal water or product on the floor. Depending on your status and responsibility, you might or might not comment on your impressions and offer suggestions. Use good sense and diplomacy. Running a busy plant with too few peopleb�0;14;the most common caseb�0;14;is hard, so a visitor should be understanding.
Look under equipment. Can it be reached for cleaning? Are the tops of equipment cabinets dusty or greasy? Does equipment have extraneous panels covering areas that must be accessed?
Are painted areas peeling? How are the floor and walls finished? Is the equipment running smoothly or are there frequent interruptions? There usually is an optimum speed for any line, but there is constant pressure on plant people to operate faster. Eventually, the optimum rate is exceeded, as indicated by frequent stops. The correct response is to reduce operating rate until the time between stops is significantly longer. Net production almost always increases at the lower optimum rate because there is less down time and better quality. It makes no sense to produce poor quality product faster.
Characterizing the Plant
Can you sketch the process flow diagram after your tour? How many products and processes are made and used? Is the plant wet or dry? Refrigerated? Dusty? Does it feel crowded? Has it been expanded? Can it be further expanded? What are compatible processes or products?
How are wastes handled? What are the wastes? Are efforts made to reduce waste? Almost any plant can reduce its water use by such methods as recycling cooling water, controlling flow from hoses, and reusing cleaning water.
How is air flow controlled in the plant? Is there a risk of cross contamination from raw to finished goods? Are there differences in room pressures? (You can tell by how hard it is to open some doors.) Are there air curtains at doors from the outside?
Did you notice a rodent control program? There should be professional traps around the inside wall. Is there a clear path around the inside wall? Often there is when the facility is built, but it gets filled over time with tools, boxes, and equipment. Are there traps and a clear path around the outside wall?
Is there an insect control program, such as UV traps? What type of lighting is used? Are outside lights mounted on the building or at a distance? Mercury vapor lamps attract insects and are best used away from the building. Rodent and insect control programs should be provided by professional experts who are properly licensed.
How are the processes controlled? It is increasingly common for food processes to be controlled through computers and graphical human machine interfaces (HMI). So far as you can tell, do the processes reflect the latest developments in the appropriate fields? It is expensive and not always necessary to continuously upgrade equipment, but it is a sign of visionary management when selective investments are made in process improvements.
Where are the people in the plant? Do they seem busy? Are they performing physical labor or are they mostly watching and tending operating equipment? Are many inspecting product? It is increasingly commonB for line operators to be responsible for quality assurance on the line. There often is a special bench where pictures of gold standard products are posted with computer terminals for entering data.
Are there visible distinctions among workers, such as color-coded smocks? This is often done to indicate where workers are supposed to be, to identify maintenance workers, and to identify visitors. Do workers have picture ID cards? Do doors require codes or electronic key cards to open? Are there sanitizing hand wash stations and footbaths at entrances?
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A dry baking mix plant in Europe was built as a multi-level tower to take advantage of gravity flow, with staging on one level, mixing on the next, surge bins on the next, and packaging on the lowest. The equipment was modern and automated, but the mixer chosen was difficult to empty completely, which posed a challenge when changing formulas. More significant, however, was the fact that each floor was made of open metal grate. The concept, evidently, was to permit air flow through the floors so there could be a common dust-collection system. Grate is also lighter than a solid floor of poured or pre-cast concrete. However, the open grate permitted dirt from workersb�0;19; shoes to fall through to the level below, posing a real threat of contamination.
In one very large plant, the cafeteria seemed always to be full. Upon inquiring, it developed that there was an aggressive union and generally hostile relations between workers and management. Efforts at discipline had been unsuccessful. A new plant manager succeeded in discharging a small number of persistent malingerers, and suddenly productivity improved and the cafeteria seemed less full, except at lunch time.
A large canned pet food plant had no refrigerated storage for its meat and poultry ingredients. Instead, unprotected blocks of frozen meat were stacked on the bare concrete floor. Blood, fat, and pieces of meat were all over the floor, making walking challenging. In contrast, many other pet food plants are as clean and safe as most food plants. Pet food plants should be built and operated like human food plants because pets are susceptible to many of the same hazards as humans are, and, inadvertently or deliberately, humans consume some pet foods.
This month's column is based on a chapter from a recently completed manuscript for Case Studies in Food Engineering: Learning from Experience, to be published by Springer in mid-2009.
Plant Tour Pointers
Much can be learned by careful observation during a tour of a food plant.
• Material handling is at the heart of many food processes and greatly influences the design.
• The state of worker morale and management effectiveness can often be discerned by observation of housekeeping and worker behavior.
• A visitor should remember he or she is a guest and should offer comments, if any, tactfully and appropriately.
J. Peter Clark,
Consultant to the Process Industries, Oak Park, Ill.