Food Protection Trends - July/August 2017 - 272

is to provide processors with simple and robust tools for
precooking tuna.
The sampling plans proposed here are intended to be
used within the context of tuna processed as described in
FDA's HACCP Guidance (15) and the National Fisheries Institute (NFI) Tuna Council's HACCP for Canned
Tuna Handbook (33). This strategy should include: (a) an
approved supplier program, (b) inspections for decomposition and histamine levels upon receiving, (c) controlling the
time and temperature exposure prior to precooking within
safe limits, and (d) precookers validated as per NFI Tuna
HACCP Handbook (33).
The authors plan a future manuscript that will provide
processors with the prerequisites and tools to use the CLs
and sampling plans developed herein. If a tuna processor
chooses to monitor fish core temperature as a HACCP
strategy to determine the adequacy of the heat treatment at
the precooking CCP, they will need to develop a monitoring
plan based on acceptance sampling to infer the minimum
core temperature, since they cannot measure every single fish
in each batch. DeBeer et al. (8) concluded that predicting
precooking time cannot be an exact science because of the
variability inherent in the fish.
The conditions that must be met to use core temperature
as a monitoring technique are (a) collection and prompt
analysis of the core temperature data after precooking, to
determine if the CLs are met or if a Corrective Action is
required, and (b) statistical confidence that the tuna flesh has
been heat treated long enough to achieve a 5 log10 reduction
in M. morganii. If these conditions are met, a statistically
valid core temperature sampling plan could be employed to
confirm that the tuna flesh has been heated sufficiently and
thus that the formation of histamine can be controlled.
Acceptance sampling
The body of knowledge on acceptance sampling is
very well developed (11, 39, 42). There are two basic
sampling procedures: (a) sampling by attribute (yes/
no, or pass/no pass) and (b) sampling by variable
(individual values). The two procedures have different
sampling regimes and sample sizes for the same
confidence levels.
Multiple sampling plans were reviewed for the development of the precooking core temperature sampling plan.
The FDA Compliance Policy Guidance for decomposition
and histamine in canned tuna (13) suggests a sample size
of 24 cans. Regulatory action is recommended (i.e., the lot
fails) if two cans show evidence of decomposition by having
histamine levels exceeding 50 ppm. A sample size of 36 cans
fails with three such cans. The FDA HACCP Guide (15) suggests that 18 fish be used for incoming histamine sampling,
with the lot failing if any sample is over 50 ppm. The FDA's
Seafood HACCP Guide (15) has recommended sample
sizes for core (i.e., backbone) temperatures in at least three

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Food Protection Trends July/August

chapters: Chapter 7 (Control of Scombroid Toxin), Chapter
12 (Control of Pathogenic Bacteria toxins) and Chapter 13
(Control of Clostridium botulinum toxin). In each case, the
recommended sample size for monitoring a temperature CL
of 4°C was 12 fish. The Guide also recommended increased
sample size if there was a high level of temperature variability or very small fish. Chapter 13 of the Guide also has a
sample size of the three largest fish, each with a continuous temperature recording device for smoking fish to a
core temperature of 62.8°C (145°F) for 30 minutes. The
NFI Tuna HACCP Handbook (33) recommends measuring 24 fish for precooking core temperature control. The
Inspection and Certification regulations for the National
Marine Fisheries Service at 50CFR260.61 (3) has numerous examples of sample sizes for lot acceptance of fishery
products, including decomposition or unwholesomeness.
Sample size-based attributes with different levels of risk
are detailed in the International Commission of Microbiological Specifications for Foods (ICMSF) (1). A table of
different biological sample sizes and their context is listed
in Appendix A. None of these sampling plans or schemes
cited is suitable for the task of lot acceptance on the basis
of a minimum ending temperature of a sample of heated
fish, except the example in Chapter 13 of the FDA HACCP Seafood Guide (15).
A sampling plan should depend on the severity or risk
of the hazard and associated risk management (28, 29,
45). In this paper, the risks will be classified based on
confidence levels and the percent of product required to
be acceptable (7), as shown in Table 1. For example, for
Moderate Severity, processors need to be 95% confident
that at least 95% of the precooked fish in the lot achieve
a minimum core temperature to ensure the fish have
been cooked sufficiently to inhibit further histamine
formation. These statements are referred to as tolerance
intervals. Additionally, there are three types of statistical
intervals: confidence, prediction, and tolerance intervals
(34). Because processors need to be confident that a
high percentage of fish have passed a certain minimum
temperature, tolerance intervals, or limits, will be the
focus of this paper.
A sampling plan in which the minimum core temperature
of the fish is attained requires
1. knowledge of whether the shape of the distribution of
the core temperature data is normally or near-normally
distributed,
2. a decision on the confidence level and reliability or
percent acceptable, based on the severity of the hazard,
3. a decision on the type of acceptance sampling plan to
use (attribute or variable), and
4. the sample size (number of fish tested), which is
determined by the aforementioned 3 items and are
included in this paper.

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