Sampling is either performed by a 3rd party or by the on farm food safety personnel. More
commonly with a 3rd party, but at a higher cost. Costs associated with sampling and sample
handling supplies, storage and shipment of the samples to the laboratory and the testing make
up the bulk of the cost.
2.9.2. Type I and type II errors
Type I error is typically referred to as not detecting a positive, or a false negative. This error has
potential for high public health significant as contaminated product could enter commerce. Type
II error occurs when there is a false positive, resulting in discarding of a saleable product and
has high economic impact on the producer. The consequence of each error type must be
considered in field sampling programs and testing methods.
2.9.3. Cost of not detecting a public health risk
Must first define what is considered a public health risk. With that assumption, not detecting a
public health risk could result in illnesses and even deaths which lead to recalls and damage to
the brand which often extends to the rest of the industry.
2.10. Sampling the whole plant vs. individual leaves
This decision will likely be product/variety specific. Baby greens will be whole plant/leaf
whereas within the context of this paper, it will be individual leaves of Romaine. There is a
debate on sampling the inner vs. outer leaves of Romaine. Industry seems to prefer to sample
the inner leaves because the outer leaves are often trimmed and discarded as a result of UV
exposure and quality degradation. While the outer leaves are more exposed to the environment
and contamination, they argue that this contamination may die off as the result of UV exposure
and desiccation. The inner leaves may remain protected from the elements, along with the
potential contaminant. Others argue that discarding the outer leaves may reduce the chance of
detecting the contaminants and thus increasing risk of accepting a potentially contaminated
product.
3. Considerations in field sampling (Nye Hardy, Donna Lynn Browne)
3.1. Four considerations in regard to field sampling are: (a) training for samplers, (b)
adequate supplies, (c) A test-hold program, and (d) an understanding that sampling
cannot be performed for all fields due to a variety of conditions.
3.2. Training for samplers must occur before sampling is done and at least annually every
year thereafter. Samplers must fully understand basic aseptic technique and know the
varying techniques for sampling each commodity. Samplers must never sample
anything that has been in direct contact with the ground.
3.3. Adequate supplies such as bags, ice chests, gloves, hairnets, sanitizing materials,
labeling and other documentation are needed. Samplers require field-worthy vehicles,
since many areas can be remote and/or have difficult terrain. The management of
employees, ordering and inventory of supplies, and care and maintenance of vehicles
must also be taken into account.
