Procedures guidelines a practical approach to aseptic performance

The Aseptic Performance of a Production line for Commercially Sterile Products depends on several factors Quality of raw material content of bacterial If applicable mixing and re-hydrat

A practical approach to Aseptic Performance

FSQ-588014-0101

1 Introduction 4

2 Checklists 5

2.1 Introduction to the Checklist 5

2.2 Guideline to the checklist 5

2.2.1 Milk Reception 5

2.2.1.1 Raw milk temperature 5

2.2.1.2 Microbiological raw milk quality 5

2.2.1.3 Bacterial Spore Count 6

2.2.1.4 Acidity 6

2.2.1.5 Alcohol stability 7

2.2.2 Raw Material 7

2.2.3 Pre-processing 8

2.2.4 UHT-processing 8

2.2.4.1 Pre-sterilising 8

2.2.4.2 Production 9

2.2.4.3 CIP 9

2.2.5 Aseptic product transfer and storage 10

2.2.6 Filling and packaging 11

2.2.6.1 Filling room 11

2.2.6.2 Raw material (Packaging material) 12

2.2.6.3 Hydrogen peroxide 12

2.2.6.4 Pre-sterilising 13

2.2.6.5 Production 13

2.2.6.6 Package integrity 13

2.2.6.7 Samples for laboratory control 14

2.2.6.8 CIP (Cleaning In Place) 14

2.2.6.9 COP (Cleaning Out of Place) 15

2.2.6.10 External cleaning 15

2.2.7 Downstream packaging 15

2.2.8 Finished product storage 15

2.2.9 Laboratory 15

2.2.9.1 Records and documentation 16

2.2.9.2 Consumer complaints 17

2.3 Checklist (could be customised for application) 18

2.3.1 Reception 18

2.3.2 Pre-processing 18

2.3.3 UHT-processing 18

2.3.4 Aseptic product transfer 19

2.3.5 Aseptic storage 19

2.3.6 Filling and Packaging 19

2.3.7 Downstream packaging 20

2.3.8 Finished product storage 20

2.3.9 Laboratory 20

2.3.9.1 Records and documentation 20

2.3.9.2 Consumer complaints 21

2.4 Summary of findings 21

2.5 Actions required 21

3 References 22

As a preventive action this Guideline could be used as a checklist for QA and Internal revision

The document is supplied as a guideline only, not as a guarantee in itself The document

is not intended to be prescriptive nor does the document claim to be complete It presumes that all relevant equipment operating manuals, recommended maintenance schedules, as well as generally accepted good manufacturing practices etc are followed Whenever there is an unsterility situation a systematic troubleshooting approach is

preferred The FiSQA experience can be of help during the performance of systematic

troubleshooting

If the intention is to identify improvement possibilities the FiSQA Plant Quality Review

(PQR) can be used, as it is an independent evaluation of the manufacturing capability for

all type of food products The PQR covers every aspect from raw materials to packages

on the shop shelf, which has an impact on the finished product quality The structure to identify possibilities for improvements goes from a General overview via Comprehensive investigation to the Implementation plan

The Aseptic Performance of a Production line for Commercially Sterile Products depends

on several factors

Quality of raw material (content of bacterial

If applicable mixing and re-hydration

during the Pre-process steps (content of

bacterial spores)

Process survivors causing unsterility

Heat-treatment in UHT-Process equipment

(time / temp Ratio)

Insufficient UHT-treatment

Quality of raw material (content of bacterial

spores) Environmental contamination

Insufficient Packaging material sterilisation

Heat / chemical-treatment of packaging

material in Aseptic Filling machine (Time,

temp, conc.)

Insufficient Packaging material sterilisation

Status of all equipment in the

production-line (leakage, damage, faulty-non aseptic,

maintenance)

Re-infection

CIP-result (remaining soil) Insufficient pre-sterilisation

Pre-sterilisation of UHT-Process and Insufficient pre-sterilisation

Note: All documents mentioned in this guideline can be downloaded from the FiSQA homepage on Orbis, or ordered from FiSQA directly

2 Checklists

2.1 Introduction to the Checklist

It is a common situation that major problems or visible damage is causing unsterilities

To prevent an unsterility situation, a checklist with checkpoints might be a help to avoid the problem

The customers engineer, a Tetra Pak service engineer or a FiSQA person could use the checklist Knowledge is needed to understand an aseptic production line, components

name, function and position

The following guidelines will serve as a help to inspect a production line in a systematic way

2.2 Guideline to the checklist

2.2.1 Milk Reception

2.2.1.1 Raw milk temperature

What is the temperature during reception of milk? The temperature of the raw milk after milking, transportation and storage is of utmost importance for the microbiological quality of the raw milk The temperature has direct impact on the ‘Standard Plate Count’

of the raw milk and influence the amount of bacterial spores The European Union e.g is laying down the following rules:

“If the milk is not collected within two hours of milking, it must be cooled to a

not daily While the milk is being transported to the treatment and/or processing establishment its temperature must not exceed 10°C.”

The optimum temperature to keep the microbiological raw milk quality under control is

4°C

2.2.1.2 Microbiological raw milk quality

The microbiological quality of the raw milk has an important impact on the protein stability (sedimentation) and organoleptic changes during storage time It can have an effect on the free amino-N content as a result of proteolysis by extremely heat resistant enzymes, often produced by psychrotrophic bacteria (1) Furthermore it influences the spore count in the raw milk, which is critical for the aseptic performance

The European Union e.g specifies the microbiological raw milk quality as follows: *

Raw cow's milk intended for the production of heat-treated drinking milk, fermented milk, junket, jellied or flavoured milk and cream must meet the following standards:

Plate count 30°C (per ml)

Whereas the USA FDA regulation says: *

Standards for Grade “A” raw milk and milk products for Pasteurization, pasteurization or Aseptic processing:

Ultra-Individual producer milk not to exceed 100 000 cfu/ml (32°C) prior to commingling with other producer milk

Commingled milk not to exceed 300 000 cfu/ml (32°C) as prior to pasteurization

Somatic cell count (per ml) in milk from individual producer not to exceed 750 000 / ml

(Further details can be found U.S Food and Drug Administration Centre for Food Safety & Applied

Nutrition Grade "A" Pasteurized Milk Ordinance 2001 Revision May 15, 2002)

* In countries where the regulations from the European Union or the FDA are not applicable, national rules have to be followed If no national rules apply the European Union or FDA standards respectively could be considered as a guideline

2.2.1.3 Bacterial Spore Count

The amount of bacterial spores is critical for the Aseptic performance Following

guideline could be given for raw-milk if an AQL* of 1/1000 defective packages in the

end product is aimed for, in 1000 ml packages The figures given in the table below can only be seen as a very rough indication of what should be recommended in terms of spore load based on a 9 log reduction during processing:

Guide for Thermoresistant Spore count in UHT processing*

(Sample taken from balance tank of sterilizer)

Total amount of Spores (Mesophilic spore count)

<100 1000 10 000

Thermoresistant spores (Thermophilic spore count)

Note that pH varies in milk from different animals and in different countries

The pH relates to sedimentation during storage Even a small deviation from the normal

pH increases precipitate of a protein/fat mixture A “sandy” flavour defect results It has been suggested that the drop in pH in the raw milk should not exceed ~0,02 units (2)

2.2.1.5 Alcohol stability

Alcohol stability will impact running times in the Pasteurizer and in the Sterilizer The product scaling will increase and possibly give a non-satisfying CIP-result A suitable method for checking alcohol stability in milk is to take equal volumes of milk and ethylalcohol and mix them Typically concentrations of 68, 72, 74 and 80 % alcohol are used Apply 2 ml milk and 2 ml alcohol on a Petri-dish or a test-tube and swirl it If coagulated/ flocculated = positive test

IDF recommends a minimum alcohol number of 72, whereas Tetra Pak suggests 74

(2)

Alcohol test is not used for high acid products

Is the raw product within the company specifications/ AQL?

(AQL= Acceptable Quality Level)

2.2.2 Raw Material

What type of raw materials are used and what about the microbiological quality?

Apart from the raw milk other raw materials like water, sugar, milk powder, chocolate powder, emulsifier, stabilizer, juice concentrates and different flavor ingredients, etc are having significance for a wide range of aseptically filled products

For the aseptic performance the microbiological quality of the raw material is of importance A high microbiological load in the raw materials can add up during the different pre-process steps, like mixing and blending, to a level where the microbiological safety is no longer ensured during the process steps Special attention should be paid to the load of sporeforming units since the microbiological result obtained from a given UHT treatment is determined by the spore count (2)

Guide for Microbiological count in some of the common raw materials The figures are based on practical experience and applied by many food producers in the world (5) The figures given in the table below can only be seen as a very rough indication of what should be recommended in terms of microbiological load, as this figures are very much depending on the type of product produced and the quality demand of each individual food producer

Product Type Total

Count

Mesophilic Spore count

Thermophilic Spore count

(All values are expressed as cfu/g or cfu/ml, respectively)

*Furthermore water should be free of pathogenic microorganism This is fulfilled if in

100 ml no Escherichia coli and no Coliforms can be detected

**At an incubation temperature of 20°C and 36°C respectively

reduce the microbiological load from the chocolate powder (See “Procedures for

Production of UHT Chocolate Milk Beverage”; FiSQA)

In general, it is recommended to have a certain soaking/maturation time for formulated products before UHT-treatment, usually between 8-12 hours at 4-6 °C The intermediate product is filtered afterwards by a double filter of 180 to 200 mesh (75 micron)

An intermediate storage before UHT-process is critical in terms of temperature and time Sampling for chemical and microbiological analyses should be done prior to UHT-processing The product has to be within specifications to continue further processing

Note: The water quality (not only microbiological but also chemical quality) is of utmost importance when recombining milk, or mixing beverages Check for records from water analyse, which should be done regularly The quality should fulfil local regulations If this is not done an analyse should be carried out

Note: When mixing high acid products it is of utmost importance to reach proper pH value in the product prior to the heat treatment The temperature of the treatment is chosen after the acidity in the product, e.g juice with a pH of 3,5 is usually pasteurised between 90 and 95 ° for 20-30 seconds whilst a juice with a pH of 4,5 (e.g tomato juice) needs around 122 °C for 20-30 seconds to eliminate microorganisms able to multiply in such product

The pH value in beverages is commonly adjusted by adding Citric acid

Is the pre-processing within the company specifications?

2.2.4 UHT-processing

2.2.4.1 Pre-sterilising

Check the function of pre-sterilising Critical points are time and temperature Where the temperature-guard is placed is crucial It should be placed on the return-line from the Aseptic Filling Machine (AFM), or return-line from Aseptic tank

(Supposedly the coldest places in the pre-sterilisation circuit)

Commonly, pre-sterilising for Low-acid application is carried out for 30 minutes at minimum 130 °C (90-120 °C for High-acid application)

Check the settings for the timer and temperature-guard in the PLC-registers

What happens if the temperature falls below the setting in pre-sterilising? The timer should restart from 0 when correct temperature is obtained

Is the pre-sterilisation within specifications?

2.2.4.2 Production

During production the time/ temperature-ratio is critical Check the volume of the holding-cell, versus used capacity (flow)

Use following equation to calculate the holding-time;

Following table show volume in pipes (SMS);

Diameter(mm-outer) Liter/ meter

accordingly (See “Guidelines for assessing the appropriate cleaning interval for

TTA-Steriliser”, FiSQA)

Commonly, UHT-treatment* of Low-acid products is carried out between 135 and 150°C

for 1 to 6 seconds (Plain, white milk*), and of High-acid products between 85 and 95°C for 20-30 seconds Other temperature programs might be used depending on products and process equipment Viscosity, particles and pH are parameters influencing the choice of temperature program A temperature-guard should be placed in the end of the holding-cell, guarding that the sterilising temperature never falls below lower limit (Tetra Pak standard 133 / 91°C for low / high acid, respectively)

Check automatic recorder paper Is the temperature deviating during production?

Is the production within specifications?

*According to EU legislation Council Directive 92/46/EEC: UHT milk must have been obtained by applying to the raw milk a continuous flow of heat entailing the application of a high temperature for

a short time (not less than +135°C for not less than a second)

Parameters that serve for an effective CIP are;

Parameter Tetra Pak recommendations TTA-Flex

Time 50 min Alkali / 30 min Acid Temperature Productin temperature for alkali (e.g 138°C) and

105°C for acid (holding cell) Concentration 2 % alkali / 1 % acid

If the CIP-result is not satisfactory (present residues), improvements have to be done to

the CIP-parameters (See “Guidelines for assessing the appropriate cleaning interval

for TTA-Steriliser”, FiSQA)

2.2.5 Aseptic product transfer and storage

The denomination “Aseptic product transfer” of a plant means the part of the plant downstream (after) the holding-cell, all the way to the last filling-machine and further a few meters It is likely that re-infection takes place in this part, if something is malfunctioning

Start at the holding-cell, and then follow the entire “Aseptic product transfer” Look for leaks, suspicious welds (quality), rolled connections, gauges, unions, valves, steam traps, backpressure valves, dead ends etc A dead end should be no longer then 1,5 times the pipe diameter

Each and every component in the aseptic product transfer of a plant is adding a potential risk to aseptic performance

If aseptic tanks are part of the aseptic product transfer, they are usually pre-sterilised by steam Piping must be properly designed, avoiding “ups and downs” that could collect condensate Measure the temperature of such places with a surface thermometer during pre-sterilisation (>125 °C should be reached in each part)

Open the system, in some critical places (e.g end-valve-cluster), after CIP to check the CIP-result

Check if regularly service and maintenance is done of the aseptic product transfer

The denomination “Aseptic storage” means Aseptic tank systems, which serves as a buffer to obtain a more flexible production

Critical points are sterile air filters, steam barriers, aseptic valves, agitator, sterilisation, over-pressure and CIP-result

pre-Check the sterile air filters Are they clean (visual and smell), dry, any visible damage? What is the interval for replacement?

Check the temperature of the steam barriers during production Normally, a steam barrier should keep >110 °C Note that a steam barrier should not be too hot Exceeding 125°C will give unnecessary wearing of seals, and might create product scaling Steam barriers are normally situated at tank-valve cluster, agitator and end-valve-cluster

Some products require that an agitator is used, depending on viscosity, separation etc If

no such products are produced, the agitator should be removed and the hole sealed with a

Check that the Aseptic valves are in good condition Is regularly service and maintenance done?

Check that the pre-sterilisation is carried out properly Commonly, Aseptic tanks and product-lines are pre-sterilised together by means of steam 30 minutes at >125 °C is required Temperature guards should be placed in critical positions like valve-cluster, sterile air filter and end-valve-cluster

What happens if the temperature falls below the lower limit during pre-sterilising? The timer should restart from 0 when the right temperature is obtained

Check the overpressure in the tank during pre-sterilisation, cooling and production A minimum of 0,5 bar should always be kept Is there a guard for low-pressure?

Check the CIP-result by opening the tank and inspect the inside with help of a torch (Agitator, top, bottom and the sprayball) At the same time look for rust or cracks If necessary, climb inside the tank

Open a valve in the valve-cluster, check for residues

2.2.6 Filling and packaging

2.2.6.1 Filling room

The requirements of a filling-room could be referred to “Guideline for the Hygienic

Production of Liquid Food, Part 1; FiSQA”

In general, the filling-room should be separated from the rest of production Doors should

be kept closed and there should be an overpressure of filtered air in the room This implies especially for open filling systems as TBA/3, Tetra Fino, A1/P1 and Classic Placing air settle plates in different parts of the room could check the air quality in the room Prepare PCA plates, Yeast and Moulds Leave the plates open for 15 minutes in the room Incubate the plates accordingly and evaluate the result One reference is maximum

40 cfu/ 100 cm2 , total count

However the usage of an air-sampling device is recommended due to a much higher accuracy Unfortunately there are no recommendations regarding acceptable limits of air

bioburden in production rooms of aseptic food plants According to data from tests the air microbial load in production rooms of UHT - (aseptic) dairy plants within the range of 500-1000 cfu/m3 is regarded as OK (measured with an air sampling device) This data must be lower, if it comes to non-aseptic machines filling pasteurised products

Radmore and Lück (1984) proposed the following:

Total count: Good = < 200/m3; Poor => 2000 /m3

Yeasts and mould count: Good = < 100/m3; Poor => 1000/m3

These proposals have been made for production rooms of cheese, milk powder, butter and condensed milk Proposals regarding production of UHT milk, pasteurised milk and juices are not available (3)