Considering the ability of food processing companies to consistently manuΒ facture safe foods with uniform quality over the past 20 or 30 years without these new tools and new systems, one might expect that quality control improvements would be marginal. On the other hand, these changes have already provided subΒ stantial opportunities for process and product improvement. This second edition is intended to update the basic concepts and discuss some of the new ones. Preface to the First Edition If an automobile tire leaks or an electric light switch fails, if we are short-changed at a department store or erroneously billed for phone calls not made, if a plane deΒ parture is delayed due to a mechanical failure-these are rather ordinary annoyΒ ances which we have come to accept as normal occurrences. Contrast this with failure of a food product. If foreign matter is found in a food, if a product is discolored or crushed, if illness or discomfort occurs when a food product is eaten-the consumer reacts with anger, fear, and sometimes mass hysΒ teria. The offending product is often returned to the seller, or a disgruntled letter is written to the manufacturer. In an extreme case, an expensive law suit may be filed against the company. The reaction is almost as severe if the failure is a difΒ ficult-to-open package or a leaking container. There is no tolerance for failure of food products.