Related Experiment Video

Updated: Jan 27, 2026

Subcellular Fractionation from Fresh and Frozen Gastrointestinal Specimens
10:07

Subcellular Fractionation from Fresh and Frozen Gastrointestinal Specimens

Published on: July 15, 2018

10.3K

Quantitative Estimation of Fecal Coliforms in Fresh and Frozen Fishery Products by APHA and Modified A-1 Procedures

S Varga1, A Doucet1

  • 1Department of Fisheries and Oceans, Fisheries Operations Branch, 1721 Lower Water Street, Halifax, Nova Scotia, Canada B3J 2S7.

Journal of Food Protection
|April 3, 2019
PubMed

Insights

The modified A-1 (A-1 M) method underestimated fecal coliforms in fish due to sediment inhibition. Adjusting incubation time and gas vial height in the A-1 M technique yielded comparable results to the APHA method.

Area of Science:

  • Food Microbiology
  • Analytical Chemistry
  • Public Health

Background:

  • Fecal coliforms are indicators of microbial contamination in food.
  • Accurate enumeration of fecal coliforms is crucial for food safety assessments.
  • Existing methods for fecal coliform detection may have limitations.

Purpose of the Study:

  • To compare the accuracy of the modified A-1 (A-1 M) method and the APHA method for fecal coliform enumeration in fish.
  • To identify factors contributing to discrepancies between the two methods.
  • To optimize the A-1 M method for reliable fecal coliform detection.

Main Methods:

  • Analysis of fresh, frozen, and breaded fish samples.
  • Enumeration of fecal coliforms using the APHA method.
  • Enumeration of fecal coliforms using the modified A-1 M method.
  • Investigation of sample sediment's effect on gas formation.

Main Results:

  • The A-1 M method yielded significantly lower fecal coliform counts compared to the APHA method.
  • Sample sediment was identified as an inhibitory factor in the A-1 M procedure.
  • Modifications to the A-1 M technique, including increased incubation time and elevated gas vials, improved accuracy.

Conclusions:

  • The standard A-1 M method may underestimate fecal coliform levels in fish due to sample matrix effects.
  • Optimized A-1 M procedures can provide reliable fecal coliform estimates comparable to the APHA method.
  • Adjustments to incubation parameters are key to overcoming inhibition in the A-1 M method.

More Related Videos

Estimating Virus Production Rates in Aquatic Systems10:49

Estimating Virus Production Rates in Aquatic Systems

Published on: September 22, 2010

13.1K
Fecal Glucocorticoid Analysis: Non-invasive Adrenal Monitoring in Equids08:02

Fecal Glucocorticoid Analysis: Non-invasive Adrenal Monitoring in Equids

Published on: April 25, 2016

10.1K

Related Concept Videos

Predicting Products: SN1 vs. SN202:27

Predicting Products: SN1 vs. SN2

Nucleophilic substitution reactions of alkyl halides can proceed via an SN1 or an SN2 mechanism. While in SN2 reactions, the nucleophile attacks the substrate simultaneously as the leaving group departs, in SN1 reactions, the substrate first dissociates to give the carbocation intermediate. Various factors such as the structure of the substrate, the strength of the nucleophile, and the nature of the solvent promote one mechanism over the other.
With increased substitution on the alkyl halide,...
16.0K
What are Estimates?01:06

What are Estimates?

It isn't easy to measure a parameter such as the mean height or the mean weight of a population. So, we draw samples from the population and calculate the mean height or mean weight of the individuals in the sample. This sample data acts as a representative measure of the population parameter. These sample statistics are known as estimates. 
The estimate for the mean of a sample is denoted by ͞x, whereas the mean of the population is designated as μ. Further, parameters such...
8.2K
Segregation in Fresh Concrete01:16

Segregation in Fresh Concrete

Segregation in fresh concrete is a phenomenon where the components of the concrete mix separate, leading to uneven distribution and compromised structural integrity. This separation typically occurs when concrete is subjected to excessive horizontal movement within forms, or when it is dropped from considerable heights or forced through narrow, winding paths. As a result, heavier coarse aggregate particles settle at the bottom, while lighter, finer materials such as cement and water rise to the...
569
Bleeding in Fresh Concrete01:22

Bleeding in Fresh Concrete

Bleeding in fresh concrete occurs when water from the mix rises to the surface. This happens because the mix's solid components fail to retain all the water as they settle, leading to separation where water collects at the top. The severity of bleeding can be measured by assessing the total settlement or by noting the decrease in height per unit height of concrete.
Bleeding can cause several issues in the concrete structure. Sometimes, the rising water gets trapped beneath large aggregate...
561
Estimation of k and VD of Aminoglycosides01:20

Estimation of k and VD of Aminoglycosides

Aminoglycosides are a class of antibiotics used to treat various bacterial infections. Clinicians must determine the elimination rate constant (k) and volume of distribution (VD) to optimize therapeutic efficacy and minimize toxicity. The k value represents the rate at which the drug is removed from the body, and the VD reflects the degree to which the drug distributes into body tissues. Accurately estimating these parameters allows healthcare professionals to tailor drug dosing to individual...
227
Estimation of the Physical Quantities01:05

Estimation of the Physical Quantities

On many occasions, physicists, other scientists, and engineers need to make estimates of a particular quantity. These are sometimes referred to as guesstimates, order-of-magnitude approximations, back-of-the-envelope calculations, or Fermi calculations. The physicist Enrico Fermi was famous for his ability to estimate various kinds of data with surprising precision. Estimating does not mean guessing a number or a formula at random. Instead, estimation means using prior experience and sound...
7.5K