Steaming of Dried Produce 2018

Steaming of dried produce: Guidance to minimize the microbiological risk

1 Table of contents Purpose of this booklet

3 Purpose of this booklet Content overview Microbiological food safety for Content overview This booklet helps you to understand steaming of dried produce Microbiological food safety for steaming of dried produce and manage the critical elements that Dried produce (e.g. herbs, spices, (root) 5 Field of application: Dried produce and steaming impact microbiological food safety vegetables, fruits) can be contaminated 6 Steaming during steaming of dried produce. with pathogenic microorganisms Process overview • Why is it important to manage the that survive the drying process or Management of the process steaming properly; contaminate the product at a later stage 8 Best processing practices • What are the main elements to in the supply chain. 9 Maintenance of equipment control during steaming of dried 1 0 Validation produce; For some dried produce categories, Why is validation so important? • What are the main elements to steaming is a frequently applied Microbiological validation study manage for an effective maintenance thermal process to control Microbiological reduction targets of equipment; microbiological hazards (see Examples of safe processing reference conditions • Why is it important to validate and decision tree on page 6 in booklet Steaming of fresh produce (blanching) verify the microbial reduction for a “Drying of produce: Guidance to 1 2 Verification steaming process. minimize the microbiological risk”)*. Why is verification so important? 13 Good Manufacturing Practices (GMPs) On dried produce, pathogenic Why is it important to have GMPs in place? microorganisms do not grow but can Zoning survive and maintain pathogenicity Cleaning for several months or even years. The Environmental monitoring microorganisms that are considered a 14 Record keeping relevant hazard for dried products are Why is it important to store records? mainly Salmonella spp., Shiga Toxin Producing Escherichia coli (STEC) and Listeria monocytogenes. Pathogenic spore-forming microorganisms are usually not considered a hazard in dry products because the toxicity is linked only to vegetative cells that are generated after spore germination. Due to the low moisture present in dried products, spores do not germinate and vegetative cells are not formed.

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3 Field of application: Steaming of dried produce

Inactivation of microorganisms in Although steaming of fresh For fresh produce processed with microbiological hazards, the addition low moisture foods, such as dried produce, also known as blanching, drying technologies that cannot of steaming can potentially be applied produce, is very difficult to achieve is not in the primary scope of this be considered a control point for if the inactivation achieved during due to the high heat resistance booklet, process parameters of microbiological hazards (sun drying drying is not sufficient to guarantee developed by microorganisms in dry blanching are given in section and freeze-drying)*, an additional food safety. environments. For this reason, steaming “Validation” on page 11. processing step should be identified. is a technology widely applied for Steaming may potentially be applied The steaming step is generally applied the microbiological decontamination as control measure. after drying (see table below).However, of dried products. It is comprised of to maximize energy efficiency and three steps: pre-heating, steaming For fresh produce processed with reduce quality loss on final products, and air-drying (see below and section drying technologies that may be blanching of fresh produce before “Steaming” for more details). For some considered a control point for drying instead of steaming after drying technological applications, the first can be considered in some cases. two steps (pre-heating and steaming) can be combined.

Technologies that cannot be Sun drying considered control points for microbiological hazards

Freeze-drying

Technologies that may be Convective air considered control points for microbiological hazards

Fluidized bed 1 2 3

Dried produce Pre-heating Steaming of Air-drying of Dried and wetting of wet produce wet produce steamed dried produce produce Microwave (also with vacuum)

* see decision tree on page 6 on booklet “Drying of produce: Guidance to minimize the microbiological risk”

4 5 Steaming

Process overview Pre-heating is applied to wet the pro- Management of the process control parameter for microbiological The steaming of dried produce (herbs, duct surface through the condensation inactivation. To maintain overpressure spices, (root)vegetables and fruits) of steam and makes microorganisms Why is it important to measure in the steaming chamber two valves usually involves the use of satura- more sensitive to heat. In addition to product temperature and steam are present, one at the exit of the ted steam at temperatures between this, it is also used to heat the product pressure in continuous during pre-heating and one at the exit of the 95–130°C in a three-phase process: to a temperature of about 80–90°C. steaming? steaming chamber, respectively. The pre-heating, steaming and air-drying, When saturated steam is applied, continuous monitoring of the steam as illustrated above (page 4). For some Steaming is the central part of the pro- product temperature is the most pressure is important to verify that technological applications, pre-heating cess where microbiological inactivation direct indicator of microbiological the valves seal properly and no steam and steaming take place in the same takes place. The choice of the tempe- inactivation. Thus, temperature should is leaking out of the chamber. Steam processing unit. rature is based on the desired level of be continuously monitored and temperature and residence time should inactivation and the impact on product recorded during steaming. Probes can also be recorded. The drawing below represents a sche- quality (see page 11). be used to monitor the temperature matic overview of the steaming pro- in different points of the product bulk cess. Product temperature, steam tem- Air-drying is necessary to bring the (product batch mixed with air) along perature, steam pressure and residence product moisture back to the initial the steaming chamber. Steam pressure time are the main parameters to control level and to cool the product down. should also be continuously monitored, for a good management of the process. It is usually done using convective hot as it is an indirect measure of steam and cold air in sequence. temperature, and thus an additional

Produce in Steam Water Jacket Steam Jacket Temperature probe Air-drying

Pre-heating Steaming Air-drying

6 7 Best processing practices Maintenance of equipment

ACTIONS RECOMMENDATIONS Why are appropriate calibration Running of tempera- Process parameters must be considered for the worst processing ture profiling in the conditions (e.g. the highest volume throughput, lowest temperature, and maintenance important? product bulk during shortest time, the beginning (start-up) and the end (shut-down) of commissioning the process). Temperature measurements should be done in different Calibration programs for points of the machine using RecordingTemperatureDevices (RTD). measuring devices Dataloggers can also be used if the machine design allows to do so. This will give a set of temperature lines. The lowest temperature line All recording devices should be considered since it represents the worst temperature. (e.g. for temperature and pressure measurements) Continuous recording Product temperature, steam pressure and steam temperature should should be calibrated of product tempera- be continuously recorded during production. Recording Temperature at regular frequency. ture, steam pressure Devices (RTD) and pressure measurement devices should be fitted This should be done and steam tempera- in the steamer at the start and end point of the process to record at least every six ture during every pro- temperatures and pressure. months. For temperature probes an accuracy duction of ± 0.5°C is recommended*.

Continuous recording Residence time is one of the key parameters for microbiological Replacement of pressure valves of residence time inactivation. It should be determined for every product type and during every continuously monitored. For continuous processing, it can be defined When the steaming production through running trials using a sequence of product types differing process uses temperatures above 100°C, in colour or shape. This way the end of the batch is clearly visible a pressure tight valve and the time can be measured manually. The parameter which is is needed on the monitored during production is the rotation speed of the mixer, since inlet and outlet of the a fixed residence time corresponds to this speed. steaming chamber to maintain overpressure. Rotary valves are normally used for this Generation of Steam is generated in the boiler at a specific pressure. It is important application. Depending on the type saturated, dry steam to maintain a decrease in pressure along the entire steam line, down of product processed, the deterioration of the to the point of injection into the pre-heating and steaming. This valve due to abrasion from product can differ creates expansion of steam with release of thermal energy to the significantly. The lifespan of the valve should external environment that avoids any formation of condensate. In this be determined and a valve replacement plan way, the steam along the entire line is in a saturated, dry state. at regular, fixed frequency should be in place to keep good operational conditions during steaming. Management of During start-up the entire steaming line must be heated to reach the start-up and shut- target operational temperature. This will allow to reach the condi- down tion of saturated steam and avoid condensation with consequent temperature reduction. The steaming of product must not start until this target operational temperature is reached. During shut-down the product must not be treated because the temperature is decreasing below the target operational temperature.

Management of In case of a process deviating from the set parameters, a clear process deviations procedure must be in place to initiate and perform the rework or disposal of the product. *”Guidelines for the Safe Production of Heat Preserved Foods”, Department of Health, UK; Industry Handbook for Safe Processing of Nuts, GMA (2010)

8 9 Validation

Examples of safe processing reference conditions Why is validation so important? to the one of the target pathogen. Dried produce A deep understanding of the process When doing a microbiological parameters and the inactivation validation, it is important to consider Steaming of basil Steaming of whole (aw=0.45) at 85°C (pro- peppercorn (aw=0.57) achieved during steaming of dry correct protocols for inoculum duct temperature), at 75°C (product produce are key to understand the preparation and product inoculation delivers 4 log10 reduc- temperature), delivers tion of Salmonella >5 log reduction of efficacy of the process. to make sure the product physical 10 after 5 minutes. Salmonella after characteristics remain unchanged. 5 minutes. Microbiological validation study • A microbiological validation The results of a validation study are study is needed if the processing valid exclusively for the process conditions applied are less stringent parameters applied to a specific Steaming of fresh produce (blanching) (shorter time, lower temperature, product. Only if this connection is The steaming of fresh produce, also known as blanching, is a common or both) than the ones reported established is it possible to safely practice in the primary processing industry. The main objective of this as guidance (see page 11), or if apply the process parameters on a process is to inactivate enzymes that cause product degradation with quality loss (e.g. color change). Another objective of blanching is to soften another dried produce type is used, daily basis. the vegetable tissues in order to prepare them for further processing. as extrapolation from one produce Blanching is not generally considered a control point for pathogenic microorganisms. However, microbiological inactivation can take place type to another is not possible. The Microbiological reduction targets depending on the process conditions applied. The choice of temperatures

outcome of the validation should be A 5 log10 reduction of pathogenic and processing times depends on the type of product to be processed but in general steam used as baseline to establish critical bacteria like Salmonella is considered a temperatures between 85 and 100°C are applied. In the case of blanching used as a control step for microbiological hazards, a microbiological validation study should be performed. limits for processing. safe reduction target for steaming of dry • When a microbiological validation is spices.* Microbiological contamination needed a surrogate microorganism of raw materials can vary widely for type should be identified. For steaming, of product and supply chain. When the internal research and external frequency and level of occurrence of guidance* have shown that pathogenic microorganisms are known Enterococcus faecium (NRRL B-2354) for a specific raw material, a tailored

has a similar heat resistance to the log10 reduction that assures food safety target pathogen (Salmonella spp) can be calculated. and can be considered a suitable surrogate for this process. Other Processing conditions are considered microorganisms can be used as safe when scientific evidence of the surrogate if there is scientific evidence target bacterial reduction is available. that the dry heat resistance specific to the technology considered is similar

*”Clean, safe spices.” Guidance from the American Spice Trade Association (2017).

10 11 Verification Good Manufacturing Practices (GMPs)

Why is verification so important? Why is it important to have Zoning • Verification should be done at an GMPs in place? Zoning is the sepa- ration of areas with appropriate frequency on the finished GMPs (as defined by CODEX - General different hygiene product. Principles of Food Hygiene) are a levels. It can be applied • Enterobacteriaceae as representatives collection of generally recognized rules, to prevent spreading of microorganisms from of pathogenic bacteria such as procedures and practices that together a specific highly conta- Salmonella and Shiga Toxin Producing provide guidelines stating what is and minated area to other more critical processing zones. As an example, Escherichia coli (STEC) and target what is not acceptable in the food raw material reception should be separated from pathogens should be used for finished industry. GMPs must be preventive in the packing area of the steamed dried product.

product testing. their approach. They ensure that food Cleaning • Analytical data should be collected quality and food safety objectives are Cleaning must be over a defined period of time. This consistently met. considered as a process step, preparing allows to do trend analysis and better the line for production. control the process. GMPs for zones and equipments (e.g. The equipment and the process environ- air-driers) positioned after steaming ment must be clean should be carefully considered to avoid and hygienically desi- re-contamination of the product. gned so they are not a source of contamination to products. Cleaning is a mandatory action to keep the For more information on GMPs, refer to hygiene of the equipment and process facilities under control. Cleaning of zones having different “Good Manufacturing Practice (GMP) hygiene levels must be done separately using Guide for Spices” (2015), American different tools to avoid cross-contamination: Spice Trade Association.* For areas where the steamed dried product is present it is important to reduce the use of water to a minimum (e.g. avoid wet cleaning and condensation). Effectiveness of cleaning should be verified at regular frequency (e.g. visual inspection, ATP analysis).

Environmental monitoring Environmental monitoring is the testing at pre-determined frequency of appropriate sampling sites (environment and product contact surfaces) identified based on risk. Appropriate combinations of relevant pathogens and/or hygiene indicators should be analysed. The results provide the necessary information to keep the microbiological popula- * https://www.astaspice.org/food-safety/good- tion in the processing area under control and to manufacturing-practice-gmp-guidelines-for- detect any cross contamination. spices 12 13 Record keeping

Why is it important for manual recording) and keep to store records? them over time. A person should be Records show evidence that a responsible to do so. specific mitigation/control/preventive action has been taken at a specific The following are examples of records time. Therefore, it is important to that should be collected and kept collect them in a timely manner because of their importance to ensure (e.g. every 10 seconds for continuous the safety of the steamed products: recording or once for every batch

Temperature and Visual inspection pressure profiles of sheet showing new machines during effectiveness commissioning and of cleaning and new products maintenance records

Residence time on Validation and every production verification data batch

Verification parame- Environmental ters measured after monitoring data line reassembly

Corrective actions report in case of process deviations and critical limits are not met (e.g. decision about product, cleaning to be done etc.)

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