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Hurdle technology
- 1. 4/6/2022 1 HURDLE TECHNOLOGY M.Venkatasami, I.D.No:2020641005 Ph.D. (Processing and Food Engineering) Department of Food Process Engineering AEC&RI, TNAU. PFE 602 Advances in Food Engineering (2+1)
- 2. 4/6/2022 2 INTRODUCTION Food preservationmethods Control the growth of microorganisms Temperature, water activity(𝑎𝑤), pH, oxidation–reduction potential(Eh), and preservatives An optimum to minimum level Single factor – reduce nutritional quality Preference: fresh, natural, and healthy foods Hurdle technology Combination of a number of milder preservation factors Enhanced level of product quality, safety, and stability Limit or prevent microbial growth
- 3. 4/6/2022 3 CONT… Factorsused for food preservation are called “hurdles”. Hurdle groups Physical Physical nonthermal Physicochemical Microbiological Miscellaneous hurdles Influence the quality, safety and stability of foods Improper application: loss of nutrients, texture, and color Achieve synergies at low intensity Prevent the growth of pathogenic or spoilage microorganisms
- 4. 4/6/2022 4 TYPE OFHURDLES EXAMPLES Physical hurdles Electromagnetic energy (microwave, radiation), high temperature (blanching, pasteurization, baking), low temperature (chilling, freezing), packaging (active and vacuum packaging, edible film), and so on Physical nonthermal hurdles High hydrostatic pressure, pulsed electric field, pulsed light, and so on Physicochemical hurdles CO2, O2, O3, ethanol, lactic acid, lacto peroxidase, low pH, low aw, Millard reaction products, smoking, nitrite/nitrate, sulfite, spices, and so on Microbiological hurdles Competitive flora, protective cultures, microbial products CONT…
- 5. 4/6/2022 5 CONT… Foodproduct may require a different combination of hurdles The initial microbial number Conditions within the product for microbial growth Target shelf life Types of combined hurdles Hurdles is a critical control point Different hurdles achieves multi target reliable preservation effects Smoked products : Heating Reducing moisture content Smoking
- 6. 4/6/2022 6 Hurdletechnology arose from a number of developments : CONT… Consumer demands for healthier foods that retain their original nutritional properties The shift to ready-to-eat and convenience foods that require little further processing by consumers Consumer preference for more “natural” foods that require less processing and fewer chemical preservatives. Desired product quality and microbial stability
- 7. 4/6/2022 7 PRINCIPLES OFCOMBINED PRESERVATION METHODS The factors Major importance Secondary importance Heat resistance 𝑎𝑤 Heat resistance Preservatives Inhibition 𝐸ℎ Mild heating Refrigeration Canned foods
- 8. 4/6/2022 8 CONT… 𝑎𝑤 pHFermented sausages Interaction of different hurdles Improvements in food preservation Energy-consuming hurdles (refrigeration) 𝑎𝑤, pH, Eh Hurdle adjustments:
- 9. 4/6/2022 9 HURDLE EFFECT Microorganisms should not over come (“jump over”) the hurdles; Start or during storage Microbes Undesirable Few Sanitation and aseptic Processing
- 10. 4/6/2022 10 CONT… Different intensities Important Bacterial spores Inhibited Fermented sausage Nitrite, salt Aerobic microbes LAB 𝑂2Strong Synergistic effect Homeostasis, osmoregulation
- 11. 4/6/2022 11 TOTAL QUALITYOF FOODS Hurdles of foods can influence, Stability Safety Sensory Nutritive Technological Economic properties Hurdles intensity, Negative Positive Chilling at low temperature – chilling injury Moderate chilling – inhibiting the microbial growth pH- inhibits pathogenic bacteria – Taste impairs (Fermented sausages ) Intensity of hurdle
- 12. 4/6/2022 12 HOMEOSTASIS Tendencyto maintain uniformity and stability in the internal microbial cells Homeostasis Physiological systems Operating in balance under unfavorable environmental condition Preservatives - Microbes Disturb one or more of the homeostatic mechanisms Microorganisms will not multiply Remain in the lag phase Die before their homeostasis is reestablished Metabolic exhaustion Osmoregulation Osmohomeostasis (tuger - proline and betaine)
- 13. 4/6/2022 13 Stress factorin environment Homeostatic response of microbial cell Low level of nutrients Low level of metabolism, stationary phase, viable non culturable forms Low pH Removal of protons from cell, maintenance of pH gradient Low water activity Osmoregulation, accumulation of solutes, reduction of water loss, maintenance of membrane turgor Low temperature “Cold shock” response: change in membrane lipid composition to maintain fluidity CONT…
- 14. 4/6/2022 14 Stress factorin environment Homeostatic response of microbial cell Raising temperature “Heat shock” response: change in membrane lipid composition Raising levels of O2 Enzyme protection (production of catalase, peroxidase, and superoxide dismutase) from H2O2 and oxygen-derived free radicals Presence of biocides Phenotypic adaptation, reduction of cell permeability Ionizing radiation Repair of single-strand breaks in DNA Competition Aggregation of cells to show symbiosis and produce biofilms CONT…
- 15. 4/6/2022 15 METABOLIC EXHAUSTION Metabolicexhaustion Auto sterilization of foods Mild heat treatment Sausage, high-moisture fruits, and meats Unrefrigerated storage (Room temperature, 25°C) Hurdle factors (pH, 𝑎𝑤, sorbate, sulfite) Bacteria, yeasts, and molds Salmonella - fermented sausages Listeria - water-in-oil-emulsions Unrefrigerated storage Refrigeration is not always beneficial for the microbial safety and stability of foods More hurdles More metabolic exhaustion
- 16. 4/6/2022 16 STRESS REACTIONS Crosstolerance Stressed microorganisms become more tolerant to other stresses Escherichia coli O157:H7 Salmonella enterica subsp. enterica ser. Typhimurium, Listeria monocytogenes Resistance induced by, Protective stress shock proteins (PSSPs) Bacteria may become more resistant or more virulent Heat pH 𝑎𝑤 Ethanol oxidative compounds starvation of nutrients Acid-shock or acid-adapted cells tolerant to stresses Mild heating of microbial cells may increase acid tolerance
- 17. 4/6/2022 17 MULTITARGET PRESERVATION Synergisticeffect Different preservative factors Different stresses will sharply reduce energy of microbial cells Increase in the antimicrobial effect of each hurdle Synthesis of PSSPs avoided Individual hurdles at lower intensity improves product quality Antimicrobial action on different targets by the hurdles is known as “multitarget preservation Targets Cell membrane DNA Enzyme systems
- 18. 4/6/2022 18 APPLICATION Intermediate- moisture foods High-moisturefoods Integer foods Foods must be differentiated before application of hurdle technology IMFs HMFs IFs Fermented Foods Heated Foods Chilled Foods Healthy Foods
- 19. 4/6/2022 19 INTERMEDIATE-MOISTURE FOODS Storablewithout refrigeration, and cost and energy efficient 𝑎𝑤 0.9–0.60 𝑎𝑤 is the primary hurdle for microbial stability Meat Fish Fruits Vegetables IMFs Hurdles IMF’s Stability Heating Preservatives Competitive microflora Redox potential Maillard reaction pH Detection and description of micro stable IMF Effective preservative factors Preservation and quality of food with hurdle
- 20. 4/6/2022 20 HIGH-MOISTURE FOODS 𝑎𝑤>0.9 Minimally processed fresh-like products- chilled or frozen Low temperature ---- Energy consuming and costly Temperature abuse during storage ----- Reduce the stability and safety of HMF Additional hurdles besides low temperature Heating pH Eh 𝑎𝑤 Preservatives Competitive flora Hurdle technology is increasingly applied on meat and meat products HMF Emulsion-type sausage Stored without refrigeration
- 21. 4/6/2022 21 Mildheat treatment 78°C internal temperature 𝑎𝑤 (below 0.95) <---- Salt, Sugar, Milk Powder, Drying <---- Bacterial spores can survive Emulsion type sausages: High 𝑎𝑤 Improves the sensory properties Decreases microbial stability and safety Glucono-delta-lactone and sodium acetate --------- LAB reduces pH pH 5.5 Vacuum packaging Reheating at 80°C for 1h in the pouch Ambient temperature CONT…
- 22. 4/6/2022 22 CONT… Heattreatment ------- Eliminates vegetative microorganisms The low aw and pH and nitrite ------- Sausage ------- Bacillus and Clostridium spores Microbiologically stable and safe ------ Refrigeration not required Number of microorganisms decreases faster during storage --- 25°C than at 10°C Ambient temperature ---- High metabolic exhaustion Highly seasoned chopped or ground pork sausage Made with fresh (raw, uncooked) pork/ smoked
- 23. 4/6/2022 23 Newtechnologies for the preservation of high-moisture fruit products (HMFPs) – Based on GMP CONT… Blanching for 1–3min Steam Mild heat treatment 0.98–0.93 Glucose or sucrose Slight reduction of 𝑎𝑤 4.1–3.0 Citric or phosphoric acid Lowering of pH Potassium sorbate Sodium benzoate Sodium sulfite Sodium bisulfite Antimicrobials Reuse of syrup in HMFP processing is recommended after pasteurization Zygosaccharomyces bailii and Zygosaccharomyces rouxii
- 24. 4/6/2022 24 INTEGER FOODS Whole or integer foods---- Consist of large pieces of plant or animal tissue Coatings Contain and maintain inhibitory substances Protect the surface of the foods against microbial spoilage Dewatering and impregnation process Soaking foods in highly concentrated solutions Humectants or other food additions Solid foods Edible coatings and osmotic dehydration Soaking of foods Fruits Vegetables Meat Cheese fish Concentrated solutions of humectants (sucrose and NaCl
- 25. 4/6/2022 25 FERMENTED FOODS Fermented sausages, salami, raw hams, ripened cheeses, and pickled vegetables Stable, qualitative, and safe at room temperature for extended periods Microbial stability - combination of hurdles The sequence of hurdles inhibits spoilage and pathogenic : Clostridium botulinum L. Monocytogenes Staphylococcus aureus Escherichia coli Salmonella Microstructure Influences the ripening process Survival of pathogenic bacteria Ripening flora only grow in nests MIXING
- 26. 4/6/2022 26 ADVANTAGES ANDDISADVANTAGES OF HURDLE TECHNOLOGY Hurdle Advantage Disadvantage Low dose irradiation Inactive vegetative microorganisms In package treatment Additional shelf life Microbial spores resistant Consumer resistance Capital costs Modified atmospheric packaging Reduces oxidation and microbial spoilage No significant effect on pathogen Freezing Longer shelf life Thawing required Higher costs
- 27. 4/6/2022 27 High hydrostaticpressure In- package treatment Spores resistant Possibility of textural changes Chemicals (pH, salt, spices) Low cost Impact on sensory quality Protective cultures Effective against spore formers Cost of handling cultures Heat sensitivity Bacteriocins Many are heat stable Effective against spore formers Inconsistency of inhibitory effect Decompose during storage CONT… Hurdle Advantage Disadvantage
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