How to control Pseudomonas in cheesemaking Particularly with raw milk in lactic technology

Transcription

1 How to control Pseudomonas in cheesemaking Particularly with raw milk in lactic technology Cécile Laithier Institut de l Elevage Experiences and references thanks project with following partners :

2 2 Context Defects due to Pseudomonas spp. : Visual defects : yellowish, green to brownish coloration of cheese surface Fluorescence UV Bad taste : bitterness Undesirable flavour Melting texture Product depreciation : economic losses

3 Description Symptoms Description Taste Bitterness Only on the rind Visual Not fluorescent colours : yellow, green, orange, brown, pink, blue Fluorescent colours : yellow (more often), green and pink Colours as more or less widespread specks and/or coloured reflections Tactile feel Greasy, fatty aspect* 1 Sticky aspect* 2 Smell Bitternesssmell, rotten potatoes smell Persistent and strong smell in the cellar : very unpleasant odour, animal odour * 1 Greasy : résidues which stay on the fingers * 2 Sticky: Necessary energy to take off the fingers 3 Not to be confused with : Some Geotrichum, Penicillium, enterococci, bitter lactococci, Chrysosporium Sulfureum, Geotrichum if present in excess Micro-organism responsible for defect Communalities with defect due to Pseudomonas spp Yeast - Pink colouration - Often greasy, feeling damp Differences with defect due to Pseudomonas spp - Difficult to dry the cheese on the surface - Strong alcohol smell - No bitterness but spicy

4 4 Identity card Pseudomonas spp : Pseudomonas fluorescens not onlyresponsible for thisdefect Present naturally in all the environment (soil, near the root system, surface of the leaves, water ) and used in agriculture, for example in bedding conditioners or as growth promotor of germs Present in the milk and cheeses : if in excess, can cause defect Low demanding from a nutritional point of view Needoxygen to grow Form very fast biofilms on surfaces More than 200 different species Growth temperature (T C) : from 3 to 32 C (optimum : 28 C) Development limited at ph < 4,5 Produce enzymes (proteases, lipases ) responsible, if in excess, for taste (bitterness) and texture defect (greasy, fatty) Some of them can produce pigments

5 5 Origins of milk and cheeses contamination by Pseudomonas spp Milk contamination Animal housing ambience Bedding Teats Plants, soils Watter used for cleaning (public network or own supply) Milking parlour ambience In red : different level between case group and control group Residual watter Biofilms formation (water pipe, milking and milk storage equipment ) Milk contamination

6 6 Microbiological results : Milk - Total plate counts (GT) and Pseudomonas spp/gt : significant results à Median value GT case group < Median value GT control group (*) à Pseudo/GT case group > Pseudo/GT control group (*) Case group average Standard deviation Control group average Control group standard deviation General average General standard deviation Proba Pseudos/GT median value (%) 10% 8% 5% 6% 8% 7% 0,092 Log_milk_GT median value (ufc/ml) 4,22 0,68 4,68 0,40 4,43 0,61 0,079

7 Résultats microbiologiques : lait Caractérisation des statuts selon les variables étudiées Log (UFC/unité dénombrée) My Log Lait Pseudos Médiane Log Lait Pseudos My Log Lait GT (tendance) Médiane Log Lait GT * Cas Témoins Dénombrement de Pseudomonas spp dans les laits en fonction des statuts, n=15 Moyenne lait : Log (UFC/mL), Médiane lait : Log (UFC/mL), Moyenne Germes totaux : Log (UFC/mL), Médiane Germes totaux : Log (UFC/mL). Intervalle de confiance

8 8 Origins of milk and cheeses contamination by Pseudomonas spp Cheeses contamination Milk contamination Water used for cleaning Residual water Milk Inoculation Cheese dairy ambience Biofilms formation (equipment ) Cheeses contamination

9 9 How to control the defect Implementation of surface microflora Problems of microflora implementation at the end of drainage : Yes Case : 8 Control : 7 Problems of microflora implementation at the end of drainage : No Case : 7 Case : 1 Balance of milk microflora Control of acidification TEMOIN Case : 1 Control : 2 Control : 2 Case : 6 Control : 0 Control : 5 Med Pseudos/GT < 0,03 Med Pseudos/GT > 0,03 Med Pseudos/GT < 0,05 Med Pseudos/GT > 0,05 Case : 0 Control : 3 Case : 1 Control : 2 M < 1,70 M > 1,70 M < 1,60 M > 1,60 Case : 1 Control : O Case : 0 Control : 2 TEMOIN Case : 1 Control : 0 Case : 0 Control : 2

10 10 Risk factors linked to the defect Animals Milking Pseudomonas spp reservoirs Teats Bedding Animal housing ambience Milking parlour ambience Contributory factors and risk practices Damaged or dirty teats Insufficient bedding area Insufficient quantity of straw down, insufficient frequency of putting straw and bedding out, food rejections on straw beddings Humid, confined and dusty animal housing ambience Dusty ambience : Milking parlour opening on to animal housing, feeding during milking, etc. Humid cleaning of milking parlour Reservoirs to check in priority In red : discriminant factors between cases and control groups in the study

11 Risk factors linked to the defect 11 Milking Transfer Milking machine (MAT) and storage milk equipment Water used for cleaning MAT Complex MAT : length of pipes, addings or modifications of milking points since installation, number of elbows and fittings, etc. Fouling/dust milking and milk storage equipment (inside and outside) Failure to comply with parameters to clean MAT (T C at the end of cleaning < 40 C) and milk storage equipment, ineffective cleaning (dust, scale) Drastic use of product (overdosage ; systematic alternance acid/alkaline ; use of an other disinfectant, punctually or routinely) Not adapted frequency to change rubbers Evacuation milk line not regularly cleaned or difficult to clean No automatic drainage system and no drying during cleaning, residual waters Water used for cleaning contaminated with Pseudomonas spp Reservoirs to check in priority In red : discriminant factors between cases and control groups in the study In red italics : conclusions of an other study on milking machine

12 Risk factors linked to the defect 12 Storage and/or maturation Acidification Drainage, drying Ripening Ripened cheeses Milk (balance of microflora) Inoculation Microflora present in the ambience Cheese dairy equipment (all the steps) Water used for cleaning Tank Milk : Pseudo/GT > 5% Storage > 24h, too slow cooling Too important maturation : low ph renneting Contaminated culture 3 Failure to control acidification : slow acidification or in the contrary early with long time under acidic conditions Too humid or too dry cheeses Too poor or late salting Problems of microflora implantation at the end of drainage 1 Problems to control microflora Not adapted humidity and temperature of premises Malfunctioning of the ventilation Drastic use of product and/or ineffective cleaning Damaged, old, cracked cheese dairy equipment Standing water areas in the dairy and/or the equipment Water used for cleaning contaminated with Pseudomonas spp 2 Reservoirs to check in priority In red : discriminant factors between cases and control groups in the study

13 13 Conclusion Pseudomonas spp present in all the environment à impossible to be totally eliminated To limit the contamination and their development : to control practices and preserve microflora balance in the milk and the cheeses Not to focus on only one reservoir but to check the factors involved in the animal husbandry and the dairy

14 14 Guidelines (in French) Pseudomonas spp : «spp» = all species Thanks results obtained by the Pseudomonas project 2013/ Scope of application : Defects due to Pseudomonas spp in lactic technology with raw milk For advisors : the way to resolve problem in the housbandry and in the dairy Objective : To control milk contamination and the defect 14

15 Sheet for farmhouse producers (in French) 15

16 16 Transfer Web site Facebook Réseau Idele Produits laitiers fermiers