Microbial Quality of Marinara Mix

April June 1997

Report prepared by Simon Rockliff and Geoffrey Millard

Samples collected and analysed by the staff at ACTGAL

1. OBJECTIVE

1.1 To determine the bacteriological status of Marinara Mixes available from seafood outlets of the ACT.

2. Background

A previous survey was conducted in the ACT in 1994 and evidence from that survey raised some concerns about the microbiological quality of the product. The product is raw and can undergo minimal cooking in some foods before consumption. The product was surveyed for an extended range of pathogens to collect data not obtained by the last survey.

3. Survey

3.1 The survey was conducted from April June 1997 and consisted of 71 samples from 25 separate outlets with all but two outlets being sampled at least twice. Some of the outlets were sampled up to five times. The distribution of sample collection needed to be more random and this will be addressed in future surveys collected by the laboratory staff.

3.2 Samples were purchased as consumer items over the counter by the ACT Government Analytical Laboratory (ACTGAL) staff and analysed by the Microbiology Unit. The survey was designed to cover as much of the ACT market as possible therefore, only a single sample of each product was collected, from various outlets, on each occasion. The Australia and New Zealand Food Authority (ANZFA) Food Standard Code (FSC) has no standards for this product type.

3.3 Most of the product is brought into the ACT frozen and the retailer thaws the product prior to display and sale. The product was tested for the hygiene quality indicators Escherichia. coli (E.coli), coagulase positive Staphylococcus (coag+Staph) and for specific pathogens Clostridium perfringens (C. perfringens), Vibrio paraheamolyticus (V. paraheamolyticus), thermophillic Campylobacter spp (Campylobacter) and Salmonella spp.

3.4 Table 1 gives the surveys acceptability criteria.

Table 1

 

Test Organism

Good

Poor

Unacceptable

E. coli

<2#

2–1000

>1000

Coag+Staph

<50#

50–1000

>1000

C. perfringens

<50#

50–1000

>1000

V.parahaemolyticus

<3

3–1000

>1000

Campylobacter spp

Not detected*

Detected*

Salmonella spp

Not detected*

Detected*

 

# Units expressed in terms of Colony forming units (cfu) per gram. * Organism not detected in 25 gms

4. Results

4.1 E.coli was isolated from 23 (32.4%) samples. The range was from 2540 colony forming units (cfu) per gram (g) of sample.

Table 2. E.coli range for positive samples

 

E.coli range cfu/g

2–10

11–100

101–1000

Number of positive samples in stated range

17(74%)

2(9%)

4(17%)

 

4.2 Coag+staph was isolated from 18 (25.4%) of samples. The range of positive isolates for this organism was from 50 to 54,000 cfu/g of sample. Four (5.6%) samples were above the acceptable level of 1000 cfu of coag+staph/g. Seven (9.9%) of samples contained both E.coli and coag+Staph.

Table 3. Coag+staph range for positive samples

 

Coag+staph range cfu/g

50–100

101–1000

1001–10000

10001–100000

Number of positive samples in stated range

7(39%)

7(39%)

3(17%)

1(6%)

 

4.3 C. perfringens was isolated from one sample at the rate of 1500 cfu/g. This count exceeded the acceptable level of 1000 cfu/g

4.4 Salmonella spp were isolated from 2 samples. The Salmonella were serotyped as S. barelly and S. weltevreden. Neither of these serotypes have caused clinical cases in the ACT in 1996/7. An appropriate level for Salmonella in this raw product is difficult to define but its presence in a significant proportion of the samples would not be desirable. E.coli was isolated from each sample positive for Salmonella and one sample also had coag+ staph.

4.5 V.parahaemolyticus was isolated from one sample at the level of 4 cfu/g. This level is not regarded as being significant.

4.6 Thermophilic Campylobacter spp was not isolated from any sample.

4.7 Temperatures on arrival at the laboratory ranged from samples being frozen to 16.1oC.

5. Discussion

5.1 Analysis of the raw data resulted in no correlation being observed between temperature and samples positive for microbial quality hygiene indicators or pathogens.

5.2 The E.coli and coag+staph levels for the majority of samples was below detectable limits. The presence of E. coli and coag+staph are of concern as this indicates the samples are either being contaminated or improperly handled and/or stored or both. It is encouraging to see that only a small percentage of samples exceeded 100 cfu/g for E.coli (5.6%) and 1000 cfu/g coag+staph (5.6%).

6. Conclusion

6.1 The E.coli and Coag+staph results indicate a potential problem associated with inadequate practices with handling and/or storage of the Marinara mix. This problem appears to be limited to only a few random samples collected from separate premises.

6.2 The detection of Salmonella, C. perfringens in a small number of samples, while it is encouraging that these pathogens are not wide spread, is of some concern as they may survive the minimal cooking of some seafood dishes. The presence of these pathogens also supports the evidence that some of the product is being improperly handled and/or stored.