High pressure processing: Food safety benefits and considerations

Transcription

1 High pressure processing: Food safety benefits and considerations CSIRO High Pressure Processing Workshop Sandra Olivier Research Microbiologist 24 th November 2016 CSIRO AGRICULTURE AND FOOD Overview Motivators & benefits of process innovation What makes high pressure processing (HPP) so attractive? What process is right for you & how to validate Challenge testing & shelf life studies (case studies) Why high pressure thermal processing (HPTP)? Spore inactivation and chilled/shelf stable, low acid foods Path to commercialisation of HPTP Innovation to facilitate commercial scale HPT processing Summary 2 High pressure processing: Food safety benefits and considerations Sandra Olivier 1

2 The future of food preservation It s not just about innovative processing, but innovative thinking Secure a safe & stable food supply that minimises waste DRIVERS Premium convenience foods that are fresh like & more nutritious Economic growth in the food sector Need to transform the way we process / preserve foods! Flexibility to innovate 3 High pressure processing: Food safety benefits and considerations Sandra Olivier Innovation in food preservation: finding the balance Cool Plasma High Pressure Pulsed electric field Microwave Assessing the feasibility of processing technologies to deliver quality benefits & safe, shelf life extension to foods Need to control /eliminate microbes Conventional Value add; safety / stability assured Innovative 4 High pressure processing: Food safety benefits and considerations Sandra Olivier 2

3 What makes HPP so attractive? Extended shelf life Natural Retained nutrients No preservatives Fresh like VALUE ADD Taste Better colour Improved texture Covalent bonds unaffected Small molecules responsible for colour, taste & nutritive content are generally unaffected 5 High pressure processing: Food safety benefits and considerations Sandra Olivier HPP in Australia 6 High pressure processing: Food safety benefits and considerations Sandra Olivier 3

4 Effect of HPP on microorganisms Inactivation of vegetative cells of bacteria & fungi, & viruses & parasites ( 400 MPa) Pressure can cause changes/damage in cell morphology (membrane/walls), biochemistry (enzymes), genetic material (proteins) Generally Gram negative < yeast/mould < Gram positive spores Spore inactivation requires very high pressure ( MPa) & heat! High Pressure Thermal Processing (HPT) Before 250 MPa 600 MPa After INJURY INACTIVATION Listeria monocytogenes after 180 s at 600 MPa* 7 High pressure processing: Food safety benefits and considerations Sandra Olivier *Source: Hiperbaric Variables influencing inactivation by HPP Inactivation is highly dependant on a number of variable factors Extrinsic factors Pressure Temperature Hold time Post process storage conditions Storage temperature Intrinsic factors ph Water activity (a w ) Salt Sugar (Brix) Moisture content Fat Potential for synergy or antagonism during the process Potential for post process effects; latent inactivation or recovery, postinjury 8 High pressure processing: Food safety benefits and considerations Sandra Olivier 4

5 What HPP process suits my product? HPP Product category Chilled Vegetative cells Microbial targets of process Spores Pathogens Short Shelf Life ( 10 d) Low Acid Foods (ph >5) Various bacterial Extended Shelf Life (>10 d) Acid Foods (ph 5) Extended Shelf Life (>10 d) Low Acid Foods (ph >5) ±other hurdles pathogens; E. coli, Salmonella, L. monocytogenes Viruses (NoV, HAV) HPT Extended Shelf Life (>10 d) Low Acid Foods (ph >5) Extended Shelf Life (1 2yrs) Low Acid Shelf Stable Foods (ph 4.6) Spores; non proteolytic Clostridium botulinum Bacillus cereus Spores; proteolytic Clostridium botulinum Image source: Hiperbaric 9 High pressure processing: Food safety benefits and considerations Sandra Olivier How to validate a process A challenge! Challenge test How your product will perform if faced with a worst case microbe scenario CHALLENGED Shelf life study How your product will perform given the microbes in it at the time of production NOT CHALLENGED Deliberately inoculate with a specific microorganism at a known concentration Includes both pathogenic (safety) & spoilage (stability) microorganisms Challenging performance related to Process efficacy (e.g. thermal processing, HPP, HPT): Inactivation of the target Process product according to conditions that would apply in a commercial setting; same product & process specifications; it will effect the microbe response 10 High pressure processing: Food safety benefits and considerations Sandra Olivier 5

6 Challenge test design aspects What are you challenging? Setting performance criteria Target microorganism selection Inoculum preparation Replicating commercial scale in the lab When to test & how often Recovery of microorganisms Test replication for reliable validation Interpretation of outcomes 11 High pressure processing: Food safety benefits and considerations Sandra Olivier How to validate a process Shelf life testing Shelf life study How long will my product remain microbiologically (and chemically) stable? TIME TO SPOILAGE Process product according to conditions that would apply in a commercial setting & monitor both pathogenic (safety) & spoilage (stability) microorganisms Assessing shelf life duration related to Process conditions (e.g. thermal processing, HPP, HPT) Formulation hurdles (e.g. ph, a w, salt) Shelf life conditions (e.g. atmosphere, packaging, temperature [abuse], time) 12 High pressure processing: Food safety benefits and considerations Sandra Olivier 6

7 Improved safety by HPP HPP RTE deli meat Inactivation of Listeria monocytogenes no preservatives salt reduced chemical free Product NaCl (% wt/wt) Number of samples positive for growth* after treatment at 600 MPa 3.5 min 5.0 min Chicken 2.1 0/5 0/5 Shaved Chicken Breast 4.8 5/5 0/5 Turkey 1.9 0/5 0/5 * via enrichment: limit of detection 1 CFU per 25 g sample (USDA), inoculum concentration ~10 4 cfu/g Youart et al. (2010) JFP 13 High pressure processing: Food safety benefits and considerations Sandra Olivier Shelf life extension by HPP HPP orange juice Control of spoilage; yeasts no preservatives Yeast numbers after 12 weeks storage (Log 10 cfu/ml) Bull et al. (2004) IFSET HPP: 600 MPa, 20 C, 60 s Initial load HPP; 4 C HPP; 10 C Thermal; 4 C Thermal: 85 C, 25 s Thermal; 10 C Process type & storage temperature 14 High pressure processing: Food safety benefits and considerations Sandra Olivier Untreated >5 >5 Untreated; Untreated; 4 C 10 C 7

8 Why HPTP? Turning down the heat! Pressures up to MPa & moderate initial temperatures C Rapid compression heating up to high temperatures C Rapid decompression cooling Overall reduction in thermal load (F T value) delivered to food 90 Temperature ( C) Compression heating HPTP Thermal process Low acid foods with superior quality Time (min) 15 High pressure processing: Food safety benefits and considerations Sandra Olivier Why HPTP? Low Acid Foods (LAFs) Shelf Stable Ambient stable (SS) ph 4.6 Proteolytic F C = 2.8 min 12 log 10 reduction Food Safety Objective Clostridium botulinum Extended Shelf Life Chill stable (ESL) ph > 5.0 Non proteolytic F 90 C = 10 min 6 log 10 reduction HPTP = reduced high thermal thermal lethality lethality (F T )(F= T ) = deterioration in VALUE favourable ADDED product attributes Product quality Thermal lethality HPTP synergy? PATS pressure assisted thermal processing Thermal processing (TP) 16 High pressure processing: Food safety benefits and considerations Sandra Olivier 8

9 Research Focus Areas The path to commercialisation for HPTP Food Safety Assured! Gain regulatory approval & establish new guidelines Establish minimum processing conditions to meet FSO Seek regulatory approval Establish new processing guidelines/standards Commercial Impact Demonstrate that the process adds value Better quality than thermal processing HPT synergistic inactivation of spores Demonstrated reduction in thermal load Process Engineering Make it work on a commercial scale Robust equipment & economical processing Process must be scalable Suitable packaging material 17 High pressure processing: Food safety benefits and considerations Sandra Olivier HPTP for chilled LAFs Non prot. C. botulinum Log 10 reduction (cfu/ml) ~3 LOG REDUCTION Significantly less heat required to achieve same kill with added pressure! Heat only 57.5 C 550 MPa 72.5 C 550 MPa 87.5 C 550 MPa HPTP F T = ~1 min F 90 C (min) HEAT F T = 10 min Legan et al. 2008, WO A1 18 High pressure processing: Food safety benefits and considerations Sandra Olivier 9

10 A way to definitively assess HPTP synergy DIVING BELL A device that allows samples to be processed in a high pressure vessel with/without pressure being transmitted R 2 = Open system PRESSURISED HPTP Closed system NOT PRESSURISED TP Olivier et al. (2014) IFSET, 27: Open & Closed systems processed simultaneously in same vessel Samples experience the same thermal process Definitive demonstration of HPT synergy 19 High pressure processing: Food safety benefits and considerations Sandra Olivier A way to definitively assess HPTP synergy Noted improvement in inactivation with pressure (600 MPa) synergy! Bacillus spp. more sensitive to HPTP greater synergy Olivier et al. (2014) IFSET, 27: High pressure processing: Food safety benefits and considerations Sandra Olivier 10

11 Commercial scale HPTP A solution? A product canister that facilitates a HPT process in a cold HPP machine The canister layers have specially selected properties that have similar or better compression heating than the product & insulates product from temperature loss during processing The triple layered HPT canister Better heat retention through: Triple layer of insulating material Sealed with floating piston prevents cold water entering 1: Lowest compression heating 2: Compression heating water 3: Compression heating > water; active heating! Knoerzer et al. 2015, TW8951/AU/PROV 21 High pressure processing: Food safety benefits and considerations Sandra Olivier Commercial scale HPTP An innovative solution! Pre heat to C Compression fluid temp: ~15 C Pressure: 600 MPa Hold time: 15 min Temperature (~80 C) maintained over 15 minute period! Knoerzer et al. 2015, TW8951/AU/PROV 22 High pressure processing: Food safety benefits and considerations Sandra Olivier 11

12 Market opportunities for HPT processing Harnessing disruptive technology for next generation food manufacturing! Meals By Design It's food to go that you can trust to do you good! Aligned to trusted diet & wellbeing programs CSIRO innovation Taste Quality Nutrition Convenience High pressure processing: Food safety benefits and considerations Sandra Olivier Taste. Trust. Convenience. Meals By Design 24 High pressure processing: Food safety benefits and considerations Sandra Olivier 12

13 Summary Pathogen free products with use of HPP without high salt, preservatives or quality altering heat treatment Spoilage delayed & shelf life extended Remain mindful of the limitations of HPP and the effect food matrices can have on microbial inactivation potential (i.e. ph, a w, fat) HPT processing can be used as an alternative to thermal pasteurisation & sterilisation Notably less heat is required to inactivate an equivalent number of spores of Clostridium botulinum and spoilage sporeformers Opportunity to eliminate or reduce detrimental traditional hurdles used to deliver microbiological safe shelf stable & chill stable foods = VALUE ADD!! Progress is being made to make HPT processing commercially feasible & a viable alternative to thermal processing 25 High pressure processing: Food safety benefits and considerations Sandra Olivier Thank you Agriculture and Food Sandra Olivier Food Research Microbiologist t e sandra.olivier@csiro.au w AGRICULTURE AND FOOD 13