Microbial Quality and Preservatives in Fresh Pasta and Noodles

January March 1997

Report prepared by Simon Rockliff, Andrew Rigg and Geoffrey Millard

1. OBJECTIVES

1.1 The objectives of the survey were to:

  • determine the bacteriological status of pasta and noodles available in the ACT market;
  • determine the compliance rate of fresh pasta and noodles for the preservatives sorbic acid and benzoic acid according to the Australia New Zealand Food Authority's (ANZFA) Food Standards Code (the Code); and
  • compare the preservative content of pasta and noodles in this survey to a previous survey conducted by the Service.

2. Background

2.1 Microbiology

2.1.1 A small survey had been conducted in the ACT in 1991 on these product types. The results (unpublished) supported the undertaking of this larger current survey into this increasingly popular food type. The Code has a coagulase-positive Staphylococcus (coag + staph) standard for this product type and the Service decided the survey should be expanded to collect data on the products microbiological status for a range of other microorganisms.

2.2 Chemistry

2.2.1 A previous survey of 24 samples conducted in 1991 showed that 17% of the samples failed the requirements of the Code. Of the samples that failed the requirements, one sample had a sorbic acid concentration of 5100 mg/kg, over five times the permitted concentration.

2.2.2 Sorbic acid is both a naturally occurring and synthetic substance. It is used as the free acid or as a salt of the acid, using a sodium, potassium or calcium salt. It is predominantly used as a food preservative to inhibit the growth of yeasts, moulds, fungi and bacteria. Sorbic acid and its associated salts are considered to be one of the safest antimicrobial agents used in food (Sofos, 1994). The food additive code numbers for sorbic acid and its associated salts are 200203.

2.2.3 Benzoic acid is a synthetic substance and is used as the free acid or as the sodium, potassium or calcium salt. It is predominantly used as a food preservative to inhibit the growth of yeasts, bacteria and moulds and is generally considered a safe food preservative. The food additive code numbers for benzoic acid and its associated salts are 210213.

3. Survey

3.1 Sixty-six samples of "fresh" pasta were collected between January and March 1997 and analysed by both the Microbiology and Food Chemistry Units. The Microbiology Unit assessed the samples for indication of overall microbial quality by the Standard Plate Count (SPC) and E. coli analyses and for the presence of coagulase positive Staphylococcus, B. cereus and Salmonella sp. organisms. All analyses were performed on each sample. The Food Chemistry Unit tested for preservatives and for labelling compliance.

4. Standards

The standards for pasta and noodles are found in Standard B3 of the Code.

4.1 Microbiology Standards

4.1.1 The microbiological standard for pasta and noodles is as follows:

4.1.2 Standard B3, clause (5) states that "uncooked wet and cooked dried pasta when examined by the method prescribed by clause (6) of this Standard shall have a coagulase-positive Staphylococci count not exceeding 100 coagulase-positive Staphylococci per gram."

4.1.3 Clause (6) states the prescribed method of analysis as being the Australian Standard AS 1766.

4.2 Chemical Standards

4.2.1 Standard B3, clause (1b) states that biscuits, cakes, pastry and other flour products, excluding bread, "may contain

(v) not more than

(A) 1 g/kg (1000 mg/kg) of sorbic acid (or its salts), calculated as sorbic acid;

(vi) flavouring and colourings."

4.2.2 Benzoic acid is not permitted to be used in these products except as a preservative in flavourings as shown below.

4.2.3 Standard A6, clause (4) states that flavourings may contain

(g) not more than 800 mg/kg of benzoic acid or its salts; and,

(h) not more than 800 mg/kg of sorbic acid or its salts.

5. Results

5.1 Samples

5.1.1 The 66 samples consisted of 29 Hokkien noodles, six egg noodles, four fettucini mixed, four gnocchi, four rice noodles, two Shanghai noodles and 17 single items. The percentages of samples received is shown diagrammatically in Figure 1.

 

The percentages of samples received is shown diagrammatically

5.2 Labelling

5.2.1 According to the Code, products should be labelled with the preservatives they contain. Figure 2, shows that 32% of the samples analysed were packaged yet were not labelled as containing preservative.

 

Figure 2, shows that 32% of the samples analysed were packaged yet were not labelled as containing preservative
5.2.4 Figure 3, above, shows that 43% of the manufacturers products were found to contain preservative but did not claim it in their ingredients.


5.2.2 Samples categorised as Other did not have a label because it was not a requirement under the provisions of the Food Act 1992 (the Act). These samples would most likely be loose pastas bought at speciality shops and sold without any prepackaging.

5.2.3 Those samples that have been categorised as Not Labelled did come in prepackaged lots but did not specify whether they did or did not contain preservative.

5.2.4 Figure 3, above, shows that 43% of the manufacturers products were found to contain preservative but did not claim it in their ingredients. Those manufacturers that did claim preservative and were found to contain preservative amounted to 38% whereas 19% of the manufacturers either did or did not claim preservative and were found not to contain preservative in their products.

5.3 Microbiological Analysis

5.3.1 Table 1 gives the results of the microbiological testing except for the SPC which is given in Table 2

Table 1. Tests and range Positives

 

Test Organism

Negative

Positive

 

No. of Samples

Range#

No. of Samples

Range#

E. coli

61

<2

5

2 to 1,800

Salmonella sp.

66

Not detected *

Not Applicable

Not Applicable

Coag+Staph

65

<50

1

500

B. cereus

61

<50

5

50 to 8,500

 

# Range expressed as colony forming units per gram (cfu/g) unless specified. * Organism not detected in 25 grams.

Table 2. Tests and range of Standard Plate Count

 

Standard Plate Count Range #

Number of Samples

<50–100

10

101–1000

4

1001–10,000

7

10,001–100,000

7

100,001–1,000,000

9

1,000,001–10,000,000

6

10,000,001–100,000,000

18

100,000,001–1,000,000,000

5

 

# Range expressed as colony forming units per gram (cfu/g).

5.3.2 During the survey, it was noticed from the raw data that Hokkien noodles was an at risk item and in an effort to determine the significance of these results, a disproportionate number of Hokkien noodles where collected and analysed. See Table 3.

Table 3. Hokkien Noodles

 

Manufacturer

Number analysed

SPC

E. coli

coag + staph

B.cereus

1

11

5 x 104–1.7 x 108

<2–350

<50

<50–3,100

2

6

2.0–9.8 x 107

<2–>1,800

<50–.300

<50–8,500

3

3

2.5x 103 _ 2.1 x 104

<2

<50

<50

4

3

8.8 x 103–22 x 106

<2

<50

<50

5

2

7.1 x 107–1.3 x 108

23

<50

<50

6

1

3.7 × 105

<2

<50

<50

7

1

1.9 × 107

<2

<50

1,500

8

1

250

<2

<50

<50

9

1

4.0 × 107

<2

<50

<50

 

5.3.3 An indication of pathogen contamination levels is given by the E. coli, B. cereus and coag + Staph levels while the SPC analysis gives an indication of the overall microbial level in the product.

5.3.4 A sample result was considered unacceptable if the level of any of the potential pathogenic organisms, E. coli, B. cereus, coag+staph exceeded 1.0 103 cfu/g or the SPC exceeded 1.0 107 cfu/g

5.3.5 E coli, B. cereus and coag+staph were detected only in the Hokkien noodles which represented 43.9% of the total samples. They were detected at the following rates:

E. coli was detected in five of the Hokkien noodles samples at levels ranging from 2 to >1,800 cfu/g. One sample exceeded 1.0 103 cfu/g for E. coli,

B. cereus was detected in four of the 29 Hokkien noodles samples at levels ranging from 50 to 8,500 cfu/g with three samples exceeding 1.0 103 cfu/g for B. cereus,

One sample (3.4% of the Hokkien noodles) contained coag + Staph. detected at a level of

300 cfu/g. However, this sample complied with the Code,

One batch of a particular brand of Hokkien noodles had the highest level of E. coli and B. cereus at >1,800 and 8,500 cfu/g, respectively.

A total of 4 (6%) samples, all Hokkien noodles, were found to fail the above acceptability criteria,

5.3.6 The SPC for the 29 Hokkien noodles ranged from 250 to 1.7108. A total of 18 (62.1%) samples failed the above SPC acceptability criteria.

5.3.7 Salmonella sp. was not isolated from any sample

5.4 Chemical Analysis

5.4.1 There were 66 samples received by the Food Chemistry Unit and tested according to prescribed methods. Overall 23% of the samples failed the requirements of the FSC as shown in Figure 4.

 

Overall 23% of the samples failed the requirements of the FSC as shown in Figure 4.

5.4.2 The survey conducted in 1991 contained a total of 24 samples. Figure 5 shows that of the samples collected, four (17%) failed the maximum permitted concentration (MPC) of 1000 mg/kg for sorbic acid. The samples that passed the MPC did not contain any sorbic acid. Benzoic acid was not detected in any of the samples.

 

Figure 5 shows that of the samples collected, four (17%) failed the maximum permitted concentration (MPC) of 1000 mg/kg for sorbic acid.

5.4.3 For the sorbic acid analysis, 53% did not contain sorbic acid, 29% contained sorbic while passing the Codes MPC of 1000 mg/kg and 18% failed the MPC for sorbic acid as shown in Figure 6. The highest recorded concentration of sorbic acid in the samples was 3130 mg/kg.

 

the sorbic acid analysis, 53% did not contain sorbic acid, 29% contained sorbic while passing the Codes MPC of 1000 mg/kg and 18% failed the MPC for sorbic acid as shown in Figure 6.

5.4.4 For the benzoic acid analysis, the results showed benzoic acid occurring in 5% of the samples as shown in Figure 7. This means only three samples contained benzoic acid. Two of the samples contained benzoic acid in excess of 2000 mg/kg whilst the third contained benzoic acid at 25.4 mg/kg.

 

For the benzoic acid analysis, the results showed benzoic acid occurring in 5% of the samples as shown in Figure 7

5.4.5 Figure 8, shows the spread of sorbic acid results as found over the course of the testing period.

 

Figure 8, shows the spread of sorbic acid results as found over the course of the testing period.

6. Discussion

6.1 Labelling

6.1.1 The Act, s16(2), states that "[a] person shall not sell food that is packed or enclosed for sale in a manner which does not comply with an applicable standard. Penalty: $5000 or imprisonment for 6 months, or both." As 32% of the samples and 43% of the manufacturers are clearly breaching the Act, enforcement of labelling provisions for preservative ingredients, in particular, is seen as a high priority. It should be noted that almost two thirds (61%) of the samples collected did comply with the Act.

6.1.2 Samples categorised as Other did not have a label at all on their packaging. These samples would most likely be loose pasta and noodles sold without any prepackaging. According to s17(3b) of the Food Act 1992, these products do not require labelling as they are packaged in the presence of the purchaser.

6.2 Microbiology

6.2.1 The results indicate a problem with particular brands of Hokkien noodles as they were found to have unacceptable levels of SPC and pathogenic organisms. In one case, there was considerable variation in counts between Hokkien noodle samples having the same use by date and collected at the same time i.e. the E. coli count varied between <2 to >1800 cfu/g for one batch and B. cereus between <50 and 3,100 cfu/g and E. coli <2 to 350 cfu/g for another. This tends to indicate that individual samples may have been improperly handled or stored.

6.2.2 High levels of SPC can come about due to improper handling or storage practices, microbiologically poor quality raw materials and cross-contamination after processing to name but a few. The levels of pathogens are of concern as Hokkien noodles are designed for minimal cooking before serving.

6.3 Chemistry

6.3.1 From the results obtained, 23% failed the MPC for sorbic and benzoic acid. As some of the results are extremely high (that is, greater than 2000 mg/kg) they may cause a serious risk to consumers.

6.3.2 For benzoic acid, it is arguable that the sample containing 25.4 mg/kg of benzoic acid is actually from added flavours. This situation is not however, arguable in the two other samples that containing benzoic acid as their concentrations were greater than 2000 mg/kg. The manufacturers of these products have clearly breached the Act by adding benzoic acid and at a level greater than two times the allowable MPC for sorbic acid.

6.3.3 There has been a slight increase in the percentage of failures for preservatives since the 1991 survey, from 17% to 23%. As the number of samples taken in 1991 survey was so small, it is difficult to positively identify a trend.

  • 6.3.4 The Food Act 1992, s23(1), states that "A person shall not render any food for sale injurious to health. Penalty: $10,000 or imprisonment for 1 year, or both." Also, s24(a) of the Act states that "A person shall not sell food that is injurious to health. Penalty: $10,000 or imprisonment for 1 year, or both."

7. Conclusion

7.1 The compliance of the products to labelling provisions was marginally acceptable as 32% of the samples failed the requirements of the Code and the Act.

7.2 Most noodle samples were microbiologically acceptable and if they did fail the criteria it most likely occurred due to high levels of SPC. Hokkien noodles produced the worst microbiological results as a large percentage failed the SPC criteria and a small percentage were found to contain unacceptably high levels of pathogenic organisms.

7.3 The compliance of pasta and noodle products for preservatives is marginally acceptable with 23% of the samples failing the requirements of the Code.

8. Recommendations

8.1 The Health Protection Service to contact those manufacturers that failed the requirements of the Food Act 1992, the Code and the HPS microbiological criteria.

8.2 To continue to educate and enforce the requirements of the Food Act 1992 as it pertains to labelling requirements of food products.

8.3 To continue to educate manufacturers of pasta and noodles of the requirements of the Food Act 1992 and the Code for preservative concentrations. Failure to comply may result in prosecution as per the Act.

8.4 To survey these products in the future to determine their compliance status after education.

9. References

Australia New Zealand Food Authority, Food Standards Code, December 1996, incorporating amendments up to and including Amendment 32.

Food Act 1992 (ACT), reprinted as at 31 January 1996.

Health Protection Service (1991) Pasta and Noodle Survey, Unpublished

Sofos, JN Antimicrobial Agents, In: Maga, JA and Tu, AT (eds) Food Additive Toxicology, Marcel Dekker Inc., New York, 1994.

Hanssen, M and Marsden, J., Additive Code Breaker: Everything you should know about food additives in your food, revised for Australia by The Commonwealth Department of Health, Lothian Publishing Company Pty Ltd, Melbourne, 1984.