EVALUATION OF ELECTROLYZED WATER FOR CLEAN-IN-PLACE OF DAIRY PROCESSING EQUIPMENT. Yun Yu and R. F. Roberts Presented at NICMA

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1 EVALUATION OF ELECTROLYZED WATER FOR CLEAN-IN-PLACE OF DAIRY PROCESSING EQUIPMENT Yun Yu and R. F. Roberts Presented at NICMA

2 Clean in place - CIP The cleaning of items of equipment or pipeline circuits without dismantling and with little or no manual involvement on the part of the operator. CIP cleaning is accomplished by circulating solutions through the system. (Tamime and Robinson, 1999)

3 4-step CIP procedure Pre-rinse to remove residual milk (soil) Alkaline detergent circulation to remove bound protein and fat deposit Intermediate rinse to remove all traces of detergent and entrained soil cool the system down for next step Sanitizing to kill bacteria, and to retard bacterial growth

4 Conventional CIP chemicals Alkaline detergent NaOH Saponification Providing negative ions to disrupt soil Other components: sodium hypochlorite, surfactants Acidic Sanitizer Chlorine Attacking bacterial cell wall and membrane Other sanitizers: iodophors, peroxy acids

5 Electrolyzed water (EW) NaCl Solution Water Membrane Electrolyzed water generator ( Cl 2 +H 2 O HOCl+H + +Cl - Na + + H - NaOH Acidic Alkaline Principle of electrolyzed water generation (Modified from {Kim,2000} {Huang, 2008}

6 Conventional CIP Chemicals Stored in concentrated solutions Risk of burn on skin Cost Electrolyzed Water Produced on-site Safe and easy to handle More cost effective Water Salt Electricity

7 Acidic EO water Electrolyzed oxidizing (EO) water ph: 2.3~2.7, ORP: >1100 mv, Free chlorine: ppm Application (as disinfectant) Medical, dental equipment Food industry Food service (restaurant, public eating facilities) Fabrizio & Cutter, 2003, 2004, & 2005; KIM, Huang, Brackett, & Frank, 2001; Kim, Hung, & Brackett, 2000; Rahman et al., 2010; Venkitanarayanan et al., 1999, Ozer and Demirci, 2006

8 Walker, S.P., A. Demirci, R.E. Graves, S.B. Spencer, and R.F. Roberts Response surface modelling for cleaning and disinfecting materials used in milking systems with electrolysed oxidizing water. Int. J. Dairy Technol. 58: Alkaline ER water Electrolyzed reducing (ER) water ph: 10.0~11.5 ORP: -800~ -900 mv Application in CIP (along with EOW) for CIP of milking system on dairy farm Wang, X., S.R.S. Dev, A. Demirci, R.E. Graves, and V.M. Puri Electrolyzed oxidizing water for cleaning-in-place of milking systems on dairy farms Performance evaluation and assessment. NABEC-CSBE/SCGAB 2012 Jt. Meet. Tech. Conf. Northeast Agric. Biol. Eng. Conf. Can. Dev, S.R.S., A. Demirci, and R. Graves Mathematical modeling of CIP of milking systems using electrolyzed oxidizing water. Northeast Agric. Biol. Eng. Conf. Walker, S., and A. Demirci Cleaning milking systems using electrolyzed oxidizing water. Trans. ASAE. 48:

9 Research question: Can electrolyzed water serve as an alternative to conventional CIP chemicals for CIP of milk processing equipment? Hypothesis: Electrolyzed water can be used as an effective cleaning and sanitizing agent for milk processing equipment.

10 Objectives 1. Construct a pilot-sale test system, and validate its performance and cleanability by CIP. 2. Develop CIP procedure using EW for cleaning of refrigerated milk storage tanks. 3. Optimize CIP procedure using EW for a tank used to heat milk.

11 Objective 1 CONSTRUCTION, CHARACTERIZATION AND VALIDATION OF TEST SYSTEM

12 Construction of test system Overview of pilot scale test system

13 Agitator Test Vessel Jacket media TE Jacket media

14 Water Water tank Test Vessel Jacket media TE Jacket media Drain

15 Coil heat exchanger CIP tank

16 Construction of test system Water Coil heat exchanger Water tank CIP tank Test Vessel Jacket media TE Jacket media Drain Schematic of pilot CIP process test system

17 Characterization of test system Determine flow rate of each pump setting Check coverage of 360 static spray ball using riboflavin test

18 Volumetric flow rate measurements Mean flow rate (L/min) VFD pump setting Mean volumetric flow rates (L/min) at different VFD pump settings. The regression equation is: Flow Rate (L/min) = (Pump Setting).

19 Experiment: Riboflavin coverage test 3.9 L/min 1.8 L/min Riboflavin solution (0.2 gram/l) 10 L/min 6.0 L/min 8.3 L/min 19

20 Residual riboflavin pattern at different flow rates Before rinse 1.8 L/min for 1 min 3.9 L/min for 7 min 6.0 L/min for 17 min 8.3 L/min for 1 min

21 Validation To validate CIP performance of the test system, efficacy of conventional CIP was evaluated after using the tank to heat milk

22 Experiment: Validation of test system Pre-clean manually Soiling Pre-rinse Pre-clean manually: rinse -> wash -> rinse -> sanitize (water) (HC-10) (water) (XY-12) Soiling: heat whole milk to 74 C (165 F) under agitation then hold for 15 min Alkaline wash Post-rinse Pre-rinse & Alkaline Post-rinse washsanitizing: Sanitizing with water at with room Principal (3200 with ppm) XY-12 (100 ppm) temperature at for 63 C 3 min for 15 min at room temperature for 3 min

23 Cleanliness assessments 0 Pre-clean manually Soiling ( ) Cleanliness assessments ATP bioluminescence assay Residual protein detection 1 Pre-rinse 2 Alkaline wash Post-rinse 3 Sanitizing 4

24 ATP Bioluminescence Method Quantitative result : relative light units (RLU) 50 cm 2 Pocket swab NovaLum ATP analyzer

25 Protein Detection Method semi-quantitative result : 1~4 score

26 Result: Conventional CIP returned the test system to a cleaning condition Cleanliness assessments of ATP and protein measurements after different steps of CIP using commercial chemicals following conventional procedure Sampling After soiling After pre-rinse ATP Log 10 RLU = 5.38 ± 0.27 Log 10 RLU = 5.60 ± 0.35 Commercial treatment Protein (μg) Fail >100 Fail Fail >100 Fail After post-rinse RLU = 0 ± 0 Pass 0~20 Pass After sanitizing RLU = 0 ± 0 Pass 0~20 Pass

27 For swab sampling Each 50 cm 2 inner surface could be swabbed only once Does sampling location effect the variation of cleanliness measurements?

28 Test for swab sampling variability Soiling (heated) Rinse Acid sanitizing with EOW Schematic of sampling locations ( ) ATP bioluminescence assay To evaluate: location effect, swab three areas for each assessment quench effect of EOW on ATP assay, rinse with EOW before assessment repeatability between trials, repeated experiment in three times

29 log 10 RLU comparison AB A A AB AB B AB AB AB Log10 RLU After soiling After pre-rinse After sanitizing Trial #1 Trial #2 Trial #3 Average log 10 RLU comparison between trials and CIP steps

30 Summary of objective-1 A test system was constructed and characterized to evaluate CIP of milk processing equipment. Flow rate of 8.3 L/min was determined to provide adequate coverage. Sampling location was not a factor in RLU value variations. The repeatability of the test system was acceptable. The test system was able to be cleaned using a conventional CIP procedure after soiling with milk under heating.

31 Objective 2 CIP CLEANING USING ELECTROLYZED WATER FOR REFRIGERATED MILK STORAGE TANK

32 To mimic raw milk silo Inoculated bacterial cocktail: 10 ml Escherichia coli (9.1 log 10 CFU/ml) 10 ml Enterococcus faecalis (9.4 log 10 CFU/ml) 10 ml Pseudomonas fluorescens (9.1 log 10 CFU/ml) into 11.4 L (3 gal.) of pasteurized whole milk Milk Bacterial level in inoculated milk, 6.7 log 10 CFU/ml

33 Preparation of EW ph and ORP Chlorine

34 Chemical properties of EW EO Water ER Water ph ORP (mv) Total [Cl - ] (ppm) Free [Cl - ] (ppm) ph ORP (mv) [OH - ] (ppm) Minimum Maximum Average St.Dev

35 0 Pre-clean manually ` Soiling Experimental design Pre-clean manually: rinse -> wash -> rinse -> sanitize (water) (HC-10) (water) (XY-12) Soiling: Inoculated whole milk and hold at 2-4 C for 18 hours Pre-rinse Alkaline wash Post-rinse Sanitizing

36 Washing temperature and time of four treatments Pre-rinse Alkaline wash Post-rinse Sanitizing Treatments Wash Chemical Temp. ( C) Time (min) Pos Ctrl Principal EW Long ER water EW Short ER water 40 5 Neg Ctrl water 40 15

37 Sanitizing temperature and time of four treatments Pre-rinse Alkaline wash Post-rinse Sanitizing Treatments Sanitizing Chemical Temp. ( C) Time (min) Pos Ctrl XY EW Long EO water 25 1 EW Short EO water 25 1 Neg Ctrl water 25 1

38 0 1 Soiling Pre-rinse Assess the cleanliness Soiling: Inoculated whole milk to 2-4 C for 18 hours Alkaline wash ( ) Cleanliness assessments 2 Post-rinse ATP bioluminescence assay Residual protein detection Microbial enrichment analyses 3 Sanitizing 4

39 RLU results a a a a RLU b b b b c b b Pos ctrl EW long EW short Neg ctrl 10 1 After Soiling After Pre-rinse After Post-rinse Sanitizing Means of RLU values. Tukey s comparison were conducted between 16 means of log 10 (RLU) measurements. Means that do not share a letter indicates significant difference (P < 0.05) d d d d d

40 Protein results Means of protein residue levels after different CIP steps Protein (ug) After Soiling After Pre-rinse After Post-rinse After Sanitizing Pos ctrl 60 ~ ~ 40 0 ~ 20 0 ~ 20 EW long 60 ~ ~ 40 0 ~ 20 0 ~ 20 EW short 60 ~ ~ 40 0 ~ 20 0 ~ 20 Neg ctrl 60 ~ ~ ~ 40 0 ~ 20

41 Microbial enrichment analyses + - Swab 50 cm 2 using sterile alginate swab Incubate at 30 C for 48 h Microbiological enrichment results after different CIP steps Micro APC (log 10 cfu/ml) Soiling Pre-rinse Post-rinse Sanitizing Pos ctrl 6.4± EW long 6.5± EW short 6.6± Neg ctrl 6.6±

42 Summary of objective-2 A CIP procedure was developed for cleaning of refrigerated milk storage tank: Pre-rinse Wash Post-rinse Sanitizing Agent Water ERW Water EOW Temperature RT 40 C RT 25 C Time 1 min 15 min 3 min 1 min So far The use of test system for evaluation CIP procedure was validated. A refrigerated milk tank was able to be cleaned using EW.

43 Objective 3 CIP USING ELECTROLYZED WATER FOR HEATED MILK PROCESSING TANK

44 Experimental design Pre-clean manually ` Soiling Pre-clean manually: rinse -> wash -> rinse -> sanitize (water) (HC-10) (water) (XY-12) Soiling: heat whole milk to 74 C (165 F) under agitation then hold for 15 min Pre-rinse Alkaline wash Post-rinse Sanitizing

45 Experimental design Soiling Soiling: heat whole milk to 165 F (74 C) under agitation then hold for 15 min Pre-rinse Alkaline wash Post-rinse Sanitizing 4 factors, 3 levels Code WashTemp ( C) WashTime (min) SaniTemp ( C) SaniTime (min)

46 Response surface model Box-Behnken design matrix: 27 trials including 3 center points Trials Run order WTemp WTime STemp STime C 5 min 35 C 5.5 min C 5 min 35 C 5.5 min C 25 min 35 C 5.5 min C 25 min 35 C 5.5 min C 15 min 25 C 1 min C 25 min 45 C 5.5 min // // // // // // C 15 min 35 C 5.5 min C 15 min 35 C 5.5 min C 15 min 35 C 5.5 min

47 Cleanliness assessments Soiling Soiling: heat whole milk to 165 F (74 C) under agitation then hold for 15 min Pre-rinse Alkaline wash Post-rinse Sanitizing ( ) Cleanliness assessments ATP bioluminescence assay (RLU 1~4) Residual protein detection (Protein 1~4)

48 RLU3 data analysis and modeling Factors: WashTemp WashTime Percentage RLU reduction (PRR): ( (RLU2 RLU3) )100% RLU2 Transformed Response: (Natural logarithms transformation of PRR) llll( (RLU2 RLU3) ) (range: 0 ) RLU2

49 Regression model RLU2 RLU3 ln( ) RLU2 = WashTemp WashTime WashTemp WashTime 2 [ WashTemp WashTime] Factor P-value WashTemp WashTime WashTemp WashTime WashTemp WashTime (R 2 = 48%)

50 After alkaline wash and post-rinse Contour Plot of ln((rlu2-rlu3)/rlu2) vs WashTime, WashTemp WashTime ln((rlu2-rlu3)/rlu2) < > WashTemp 60 65

51 Optimization of ER water wash step New D High Cur Low Composite Desirability WashTemp WashTime [ ] [ ] Optimum wash temperature = 54.6 C Optimum wash time = 20.5 min Predicted RLU reduction = 99.08% ln((rlu2 RRRRRRR Targ: 0.0 y = d = llll( RRRRRRR RRRRRRR ) Conventional ctrl: 100% RLU reduction

52 Conclusions The test system developed was suitable for evaluating CIP cleaning of milk tanks. It was possible to CIP clean a refrigerated milk storage tank using EW. It was possible to CIP clean a tank used to heat milk using the optimal condition, but the system was not as effective as when cleaned with conventional chemicals.

53 Future research Consider methods to improve the cleaning efficacy of alkaline ER water add surfactants Increase alkalinity Add other detergent builder To improve acidic EO water Use neutral electrolyzed water with less corrosive characteristic Add corrosion inhibitors, such as silicates to acid EO water to prevent corrosion