METER GROUP PAWKIT, Operator'S Manual

Page 1: ...Portable Water Activity Measurement System Operator s Manual METER Group Inc Version July 19 2017 07 03 59...

Page 2: ...Court Pullman WA 99163 Phone 509 332 5601 Fax 509 332 5158 Website www metergroup com Email support food metergroup com or sales food metergroup com Trademarks AquaLab is a registered trademark of MET...

Page 3: ...3 1 Moisture Content 6 3 2 Water Activity 6 3 3 Water Potential 8 3 4 Sorption Isotherms 9 4 Getting Started 11 4 1 Features 11 4 2 Sample Preparation and Placement 12 4 2 1 Sample Preparation 12 4 2...

Page 4: ...cation and Calibration 27 6 1 Verification Standards 27 6 2 Steps to Verify Calibration 28 7 Support and Repair 31 7 1 Repair Costs 32 7 2 Loaner Service 32 8 Further Reading 33 8 1 Water Activity The...

Page 5: ...Monday through Friday between 7 am and 5 pm Pacific time Note If you purchased your Pawkit through a distributor please contact them for assistance Email support food metergroup com or sales food mete...

Page 6: ...inally manufactured Material and equipment covered hereby which is not manufactured by Seller shall be covered only by the warranty of its manufacturer Seller shall not be liable to Buyer for loss dam...

Page 7: ...ty Accuracy 0 02 Water Activity Resolution 0 01 Sample Temperature Accuracy 0 2 C Sample Temperature Resolution 0 1 C Read Time 5 min Sample Dish Capacity 7 5 mL Recommended 15 mL Full Operating Envir...

Page 8: ...curacy The Pawkit is accurate to 0 02 aw For many applications this ac curacy is more than adequate If you require higher accuracy in your measurements we recommend you use METER s AquaLab water ac ti...

Page 9: ...that your Pawkit operates correctly and consistently al ways place it on a level surface when measuring This mitigates the risk of sample material spilling inside the instrument To avoid inaccurate r...

Page 10: ...chemical reactions in materials The limitations of moisture content measurement are attributed to differences in the intensity with which water associates with other components 3 2 Water Activity Wat...

Page 11: ...he sample is important If a system is not at internal equilibrium one might measure a steady vapor pressure over the period of measurement which is not the true water activity of the system An example...

Page 12: ...re driving forces for moisture movement Thus in an isothermal system water tends to move from regions of high water potential high aw to regions of low water potential low aw Water content is not a dr...

Page 13: ...reduction in energy status of the water is not osmotic because the cellulose or protein concen trations are far too low to produce any significant dilution of water The reduction in energy is the res...

Page 14: ...isotherm for a fee For example if one were to monitor the water content of dried potato flakes one would measure the water activity and water content of potato flakes dried to varying degrees using th...

Page 15: ...is very simple Once you have ensured that you have a stable working environment you are ready to begin sampling The following is a description of the features and operation of the instrument 4 1 Featu...

Page 16: ...e The Pawkit is able to accurately measure a sample that leave small spaces of the cup bottom exposed For example raisins only need to be placed in the cup and not flattened to cover the bottom A larg...

Page 17: ...on the cup to restrict water transfer To seal the lid place tape or ParafilmTMcompletely around the cup lid junction It is necessary to seal the cup if it is going to be a long time before you make th...

Page 18: ...fits under the sensor into a recess in the bottom of the Pawkit A correctly positioned cup results in the Pawkit being level on the bench when sitting on the cup and the sensor cover legs Ensure the...

Page 19: ...ver tab with the other hand and rotate until it snaps into the closed position covering the sensors 4 3 Taking Measurements 1 Make sure the sample cup is positioned as described in the Sample Placemen...

Page 20: ...4 Once the measurement process has been started the Pawkit begins to display water activity measurements as well as tem perature after five seconds updating the display every second thereafter During...

Page 21: ...d and that the instrument needs to be serviced Refer to Section 7 for instruc tions on how to return your Pawkit for repair Note DO NOT lift or move the instrument during the mea surement You risk con...

Page 22: ...arded or covered with a lid if it is to be re measured at a later time 4 4 Turning Pawkit off To turn off the Pawkit leave it idle for more than five minutes and it shuts off automatically If the Pawk...

Page 23: ...ple and instrument temperatures are within 1 C If the sample is too warm the thermometer icon on the left of the screen appears You see the mercury go up the thermometer and pop out of the top and the...

Page 24: ...ab offers two sizes of cleaning kits The larger cleaning kit is primarily used for benchtop units and the compact is more useful for the handheld The following supplies are included in the compact cle...

Page 25: ...does not come off replace the filter as explained in the next section It is important that contamina tion of this filter is minimized as the relative humidity of the sample is measured via the filter...

Page 26: ...5 CLEANING AND MAINTENANCE Pawkit Figure 4 Removal of Filter Caution The capacitance humidity sensor below the filter is extremely fragile Do not touch it 22...

Page 27: ...ure remain ing from the cleaning process 5 2 3 Chamber Cleaning Instructions Wrap a new Kimwipe strip around the end of the swab included in the cleaning kit and moisten it with cleaning solution or i...

Page 28: ...several years If the battery charge is low you may see a low battery indicator icon appear in the lower right corner of the screen Note An occasional low battery indication does not mean the battery...

Page 29: ...l top and elastomer which contains the batteries from the white plastic bottom 3 Remove the old Lithium ion batteries Replace with new CR1632 or equivalent 3V lithium coin cells Make sure to orient th...

Page 30: ...ket Make sure the two small springs which make contact between the battery terminal and the circuit board are in place 4 Replace the circuit board plastic bottom in the elastomer top Tighten the two s...

Page 31: ...ific con centrations for constant and accurate water activity measurements They have been produced under a strict quality assurance regime and their accuracy is verified by an independent third party...

Page 32: ...no adjustment at this time and you may now skip to step 9 If it is not reading correctly continue to the next step Note An error code of 9 99 at any time during the process in dicates that the sensor...

Page 33: ...er changes by an increment of 0 01 8 When you have it set to the correct value press the II button to scroll until Sto appears in the lower right corner then press I This stores the new value you have...

Page 34: ...pe Changes in the intercept are more likely to occur than changes in the slope so the 0 76 verification check is the most important and should be done more frequently Review the graphical representati...

Page 35: ...the instrument please contact a METER customer support representative to obtain an RMA Shipping Directions The following steps can help to ensure the safe shipping and pro cessing of your AquaLab 1 Pa...

Page 36: ...harges for parts labor and shipping are billed to you An extra fee may be charged for rush work METER can provide an estimated repair cost if requested 7 2 Loaner Service METER has loaner instruments...

Page 37: ...f foods Academic Press New York Gmez R and J Fernandez Salguero 1992 Water activity and chemical composition of some food emulsions Food Chem 45 91 93 Greenspan L 1977 Humidity fixed points of binary...

Page 38: ...nd P P Lewicki 2001 Direct manometic determination of vapor pressure P A2 4 1 A2 4 6 In R E Wrolstad ed Current Protocols In Food Analytical Chemistry John Wiley Sons Inc New York Reid D S A J Fontana...

Page 39: ...Stamp J A S Linscott C Lomauro and T P Labuza 1984 Mea surement of water activity of salt solutions and foods by several elec tronic methods as compared to direct vapor pressure measurement Journal of...

Page 40: ...la De Ciencia Y Tecnologia De Alimentos 34 368 388 Vega Mercado H B Romanach and G V Barbosa Canovas 1994 Prediction of water activity in food systems A computer program for predicting water activity...

Page 41: ...in foods Critical Rev in Food Sci Nutr 36 465 513 Farberm J M F Coates and E Daley 1992 Minimum water ac tivity requirements for the growth of Listeria monocytogenes Lett Appl Microbiol 15 103 105 Fr...

Page 42: ...proteolytic Clostridium botulinum strains Journal of Food Protection 57 327 330 Kress Rogers E 1993 Food quality measurement Food Industry News September 23 26 Kuntz L A 1992 Keeping microorganisms i...

Page 43: ...biol 66 1274 1279 Mattick K L F Jorgensen J D Legan H M Lappin Scott and T J Humphrey 2000 Habituation of Salmonella spp at reduced water activity and its effect on heat tolerance Appl Environ Micro b...

Page 44: ...foods in relation to its water activity aw Journal of Stored Products Research 36 47 54 Park C M and L R Beuchat 2000 Survival of Escherichia coli O157 H7 in potato starch as affected by water activit...

Page 45: ...chia coli strain using nonlinear logistic regres sion International Journal of Food Microbiology 61 159 167 Santos J T M Lopez Diaz M C Garcia Lopez M C Garcia Fernandez and A Otero 1994 Minimum water...

Page 46: ...ctivity pH and temperature on the growth of osmophilic yeasts Turkish Jour nal of Biology 20 37 46 Wijtzes T P J Mcclure M H Zwietering and T A Roberts 1993 Modelling bacterial growth of Listeria mono...

Page 47: ...Ciencia Y Tecnologia De Alimentos 33 651 656 Hand L 1994 Controlling water activity and pH in snack sticks Meat Marketing and Technology May 55 56 Lee M B and S Styliadis 1996 A survey of pH and water...

Page 48: ...ller 1992 Influence of aw value and storage temperature on the multiplication and enterotoxin forma tion of staphylococci in dry cured raw hams International Journal of Food Microbiology 16 109 115 Wi...

Page 49: ...r ac tivity levels in processed salamis and sausages in Metro Toronto Journal of Food Protection 59 1007 1010 Luecke F K 1994 Fermented meat products Food Res Intl 27 299 307 Malec L S A S Pereyra Gon...

Page 50: ...ulosus marmoratus fillets under simulated retail conditions Journal of Food Science 60 636 639 Fruits and Vegetables Ayub M R Khan S Wahab A Zeb and J Muhammad 1995 Effect of crystalline sweeteners on...

Page 51: ...56 Kiranoudis C T Z B Maroulis E Tsami and D Marinos Kouris 1993 Equilibrium moisture content and heat of desorption of some vegetables Journal of Food Engineering 20 55 74 Lopez Malo A and E Palou 2...

Page 52: ...V Roa and R V Diaz de Tablante 1995 Combined stress effects on growth of Zygosaccharomyces rouxii from an intermediate moisture papaya product Journal of Food Sci ence 60 356 359 Zeb A R Khan A Khan M...

Page 53: ...M E A J Ramos L Seto P Purroy V Sanchis and S Marin 2003 Antifungal activity of volatile compounds generated by essential oils against fungi commonly causing deterioration of bakery products Harris M...

Page 54: ...in Argentina and Uruguay Journal of Food Protection 63 965 969 Seiler D A L 1979 The mould free shelf life of bakery products FMBRA Bulletin April 71 74 Sumner S S J A Albrecht and D L Peters 1993 Oc...

Page 55: ...lity Sarhad Journal of Agriculture 8 23 28 Ferragut V J A Salazar and A Chiralt 1993 Stability in the conservation of emulsified sauces low in oil content Alimentaria 30 67 69 Gleiter R A H Horn and H...

Page 56: ...rugs in the solid state International Journal of Pharmaceutics 62 87 95 Bell L N and K L White 2000 Thiamin Stability in Solids as Affected by the Glass Transition Journal of Food Science 65 498 501 C...

Page 57: ...al Journal of Food Prop erties 10 61 71 Zografi G 1988 States of Water Associated with Solids Drug Dev Ind Pharm 14 1905 1926 Zografi G and M J Kontny 1986 The interactions of water with cellulose and...

Page 58: ...on and Analysis 6 364 369 Juhan K and G K Byung 2000 Lipase catalyzed synthesis of lysophosphatidylcholine using organic cosolvent for in situ water ac tivity control Journal of American Oil Chemists...

Page 59: ...METER Group Inc 2365 NE Hopkins Ct Pullman WA 99163 USA Type of Equipment water activity meter Model Number Pawkit Year of First Manufacture 2007 The undersigned hereby declares on behalf of METER Gr...

Page 60: ...for Sampling 5 Enzymes and Water Activity 6 Equilibrium 7 of sample aw and rh 7 Gibbs Free Energy 8 Homogeneous 8 Hot Samples 19 Humidity Related to aw 4 Inserting Samples 13 LiCl Standards 27 Lids f...

Page 61: ...ulti Component 12 Sample Cups 4 12 Filling Level 12 Stainless Steel 12 Seller s Liability 2 Sensor Damage 19 Filter 21 Filter Cleaning 21 Filter Replacement 21 Sorption Isotherm 9 Specifications 3 Sto...