Establishing Spc Monitoring Procedures Haccp Principle

Selection of the correct monitoring system is an essential part of any HACCP study because it is what the HACCP team relies upon to maintain control at the CCPs. By definition, monitoring is a planned sequence of observations or measurements to assess whether a CCP is under control and produces an accurate record for future use in verification [7]. Monitoring serves to (1) track the operation of a process and enable the identification of trends toward a CL that may trigger process adjustment; (2) identify when and where there was a loss of control (a deviation occurred at the CCP) such that corrective action is needed; and (3) provide written documentation of the process control system [48].

The HACCP team will be responsible for designing the monitoring activities at each CCP, as well as training the individual(s) who will carry out the monitoring. These individuals should have the authority to stop the operation and to take corrective action if the CL is violated. All records and documents associated with monitoring CCPs should be recorded, signed, and dated by the person doing the monitoring, and, where necessary, assessed by a designated manager with overall responsibility for the food product [4]. Procedures must identify what control measures will be monitored, how frequently monitoring should be performed, what procedures will be used, and who will perform the monitoring [27].

Physical (e.g., temperature, ORP millivolts, metal detection) and chemical (e.g., chlorine, pH, acidity) monitoring systems are always the preferred methods of monitoring because of their ease and real-time data feedback. Monitoring systems may be continuous (e.g., recording on a continuous circular chart the pasteurization temperatures of juice filled into bottles) or discontinuous (e.g., measuring residual free chlorine in fresh-cut vegetable flume water at specific intervals). Monitoring equipment systems may be online (e.g., temperature and ORP probes, metal detectors) or offline (e.g., chlorine test kits, determination of titratable acidity, water activity measurements). The equipment chosen for CCP monitoring must have the degree of sensitivity to control hazards accurately. Daily calibration or standardization is necessary, and records should be maintained on these procedures, to become a part of the support documentation for the HACCP plan [27]. While microbiological testing is not suitable for controlling CCPs, the above measurements (excluding metal detection) can serve as an indirect measure of microbiological control at the CCPs.

Statistical control charting is ideally suited for HACCP monitoring of designated CCPs, because it provides an early warning signal of the need for corrective action before a CCP is violated. In terms of process control, however, all statistical control charts are not created equal. Variable control charts are much better than attribute charts in detecting an impending change in a process. This is because variable charts use quantitative data measurements while attribute charts work with qualitative data. Variable charts can pinpoint the relative position of plotted points within a CL such that if there is a move toward the boundary, or if an unusual pattern of points signals there is trouble in the process, corrective action can be taken immediately before the CL is compromised. In contrast, attribute charts utilize a pass/fail system of data gathering, and cannot signal a change until the problem has already occurred. Therefore attribute charts are poor tools for anticipating process change [49].

It is important to note, however, that process control may not be HACCP control. If the common cause variation of the parameter monitoring a CCP is too great, the process may exceed the CL. Thus, a process in statistical control may not be capable of producing a safe product. Likewise, the parameter monitoring a CCP (ORP in millivolts) may be within the CL, but not in statistical control. In fact, any one of four scenarios may exist, as demonstrated in Figure 15.6 [27]. Thus, to ensure product safety, the important point is that SPC limits must have less variability than HACCP limits [50].

It must be remembered that any statistical chart that relies on plotted data averages may obscure extreme values that could pose a health hazard [37]. While plotted averages for a CCP may be within critical limits, individual values may be above or below the CL for safety. For this reason, it is recommended to first monitor CCPs using individual values plotted on individual/ moving range charts to be certain they can remain within their predetermined CLs [49]. Once process stability has been achieved, then one can proceed to construct average/range charts. These are better indicators of any process shift that may occur for a CCP within the CL.

The availability of numerous SPC software packages has increased significantly in the last 15 years, because of listings and reviews in publications such as Quality Progress, Journal of Quality Technology from the American Society for Quality (ASQ), as well as from vendors on the Internet. Much of the fruit and vegetable industry has moved from charts on paper and clipboards to computer-controlled processing. It is now possible to load raw data into software that creates control charts and performs capability studies with great speed and accuracy. However, even though this technology is time and cost saving, there is the danger that operators do not understand the theoretical background on which these programs are based and therefore can draw inappropriate conclusions based on computer results. As Cullen and Hollingum point out, a computer will carry out complicated calculations

Chlorine monitoring

Chlorine monitoring

Chlorine monitoring

Chlorine monitoring

(c) Process out of statistical control, but within critical limits (CL)

(d) Process out of statistical control, and outside of critical limits (CL)

(c) Process out of statistical control, but within critical limits (CL)

(d) Process out of statistical control, and outside of critical limits (CL)

FIGURE 15.6 Monitoring chlorine concentration in ORP (mV) using SPC and HACCP methodology. (Adapted from Hurst, W.C., Safety aspects of fresh-cut fruits and vegetables, in Fresh-Cut Fruits and Vegetables: Science, Technology and Market, Lamikanra, O., Ed., CRC Press, Boca Raton, FL, 2002. With permission.)

very quickly, but unless the user fully understands the significance of the figures and graphs generated, the user can easily move to some extremely misleading conclusions [35]. Computers are no substitute for a thorough training in the fundamentals of SPC.

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