SANITATION OF DAIRY EQUIPMENTS (RINSE SOLUTION AND SWAB CONTACT METHODS)

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1 EXPERIMENT 10 Structure 10.1 Introduction 10.2 Objectives 10.3 Experiment Principe Requirement Procedure Observation Resuts 10.4 Precautions TESTS FOR SANITATION OF DAIRY EQUIPMENTS (RINSE SOLUTION AND SWAB CONTACT METHODS) Microbioogica Anaysis of Air and Water 10.1 INTRODUCTION Impropery ceaned and sanitized equipment and containers constitute major sources of contamination of mik and mik products. Hence it is obigatory to check the sanitary condition of pant, equipment, containers and packaging materias whose surface comes in contact with mik and mik products and to take corrective measures for the fauts or apses as reveaed by the resuts of bacterioogica examination. The methods for the examination of surface infection are numerous but in a dairy pant rinse and swab methods are preferred. Swab contact method is used for arge pieces of equipment ike tanks, cooers, pates of pasteurizer and pipeines. The rinse soution method is empoyed for examining steriity of containers ike mik bottes and cans OBJECTIVES After doing this practica we wi be abe to: reca the significance of assessment of the pant hygiene; seect and perform the appropriate samping techniques for inspection of dairy pant; anayze the sampe coected; and infer the resuts obtained from various tests in terms of sanitary conditions of dairy pant. 49

2 10.3 EXPERIMENT i. Principe Equipments. (Rinse Soution Examination of surface infections is one of the methods of Evauation of dairy hygiene and heps to achieve foowing objectives: To ensure that the pant surfaces wi not contaminate the product To trace the source or point of contamination aong the processing circuit if contamination has taken pace, To meet quaity contro requirements within the pant To ensure compiance of product with ega requirements To obtain information on checking and samping procedures use to endorse the hygienic practices adopted in the pant. Swab Contact Surface Method: The swab technique consists of appying a sterie swab dipped in an appropriate soution over a measured surface area. The swab is rinsed in a measured amount of sterie soution which is subsequenty anayzed microbioogicay. Rinse Soution Method: The sanitary conditions of containers and equipment can be evauated by repeating fushing of a measured voume of sterie, buffered sanitizer-neutraising soution over the product contact surface foowed by determination of bacteria popuation of the rinse soution by SPC method. ii. Requirements Apparatus and materia used for standard pate count method Test tubes and fasks containing ringer s or phosphate buffer soution (20 m, 25 m, 500 m) Composition of Ringer s soution: Sodium choride: 9.00 g Potassium choride: 0.42 g Cacium Choride: 0.24 g Sodium Bicarbonate: 0.20 g Distied Water: 1,000 m Composition of phosphate buffer: Potassium dihydrogen phosphate: g Distied Water: 1, 000 m Swab: Swab consists of wire gauge or cotton woo wound round the end of a meta wire. Take a piece of a meta wire (35 cm ong x 2.6 mm diameter) formed in to a oop at one end and eaving a straight ength of 30 cm and notched at the other end to hod the gauge or cotton woo. Wind a piece of 50 mm unmedicated 50

3 ribbon gauge (150 mm ong) and secure the swab with a thread. Pace the swab in 25 m of the ringers or phosphate buffer soution in a test tube, pug with cotton woo and steriize by autocaving at 120 C for 15 minutes. Equipments. (Rinse Soution iii. Procedure i) Swab Method Press the swab with a roing motion against the side of the test tube to remove excess iquid. Remove the swab and with heavy pressure rub back and forth over the area to be examined so that a parts of the surface are treated twice. Rotate the swab so that a parts of it make contact with the surface under test. Return the swab to the test tube and insert the cotton woo pug. The swabbing shoud be repeated over a spots of 10x5 cm area in different parts of the surface so that the tota area covered comes to 900 sq cm wherever possibe. Aow the swab to be immersed in the iquid for five minutes and mix by swiring the swab vigorousy in the soution six times. Remove the swab after expressing the excess iquid by pressing against the side of test tube. Prepare 1/10 diution of the sampe using a nine m. Diution bank. Transfer 1 m. Portions of the swab sampes as we as the 1/10 diution x dupicate pates and agar medium. Incubate the pates at 37 +/- 0.5 C for 48 hrs. At the end of incubation period, count the pates having and find the coony count per m of the swab sampe. This number mutipied by 25 gives the coony count of the tota area swabbed from which the count per 900 sq cm area can be cacuated. Express the resuts as coony count per 900 sq cm area of the surface of the equipment. ii) Rinse method Add Ringer s or buffer soution (20m in case of mik bottes, 500m for other pieces of equipments of size bigger than bottes) Rotate the piece of equipment to make 12 compete revoutions so as to wet as far as possibe, the whoe surface of the piece of the equipment to be rinsed with the rinse soution. Return the rinse to the botte. Examine the soution immediatey. If this is not possibe, pace in the refrigerator unti examined (preferaby within 36h) 51

4 Invert the container 3 times to mix the rinse soution. Transfer 1 m of the sampe into pates in dupicate. Prepare 1/10 diution of the sampe using a 9 m diution bank and transfer 1 m of the diution into another set of pates. Pour agar medium into pates and after the medium is set, incubate the pates at 37±0.5 0 C for 48 hr. After the incubation period, remove the pates and count the coonies, and pates having coonies from 25 to 250 shoud be used for counting. The average counts in dupicate pates (mutipied by 10 in case of 1:10 diution) represents the coony count per m of the rinse sampe. Express the resuts in terms of coony count per m (coony count per m of rinse x tota voume of rinse i.e. 20 or 500 m). Equipments. (Rinse Soution iv. Observations The pupi shoud record the foowing observations: Tabe 10.1 Examination of Sanitary Condition of Equipment Equipment Method Coony Count Average Coony Count per Used 1 2 Count Litre/900 cm v. Resuts Foowing standards are suggested as a guide for judging the sanitary conditiond of the equipment: (a) Swab Contact Method Coony Count per 900 cm 2 Less than 5,000 Grade Satisfactory 5,000 to 25,000 Fair More than 25,000 Unsatisfactory 52

5 (b) Rinse Soution method Coony Count per iter capacity Less than 1,000 Grade Satisfactory Equipments. (Rinse Soution 1,000 to 5,000 Fair More than 5,000 Unsatisfactory 10.4 PRECAUTIONS At reguar intervas, pumps, vaves shoud be opened and seas and rubbers inspected visuay especiay if products with high viscosity are processed. Whie samping from contact surfaces, a specia attention shoud be given to those paces which are difficut to cean e.g. recesses, ebows, vaves, shafts, stirrer, paddes, gauges, probes etc. The sampe container shoud be rinsed two or three times with the materia being coected before fiing. To obtain a fina quantity of 25 m of swab soution, it is necessary to start initiay with a arger quantity to aow for evaporation during autocaving. The rinse soution and swabs after samping shoud be maintained at 4 o C and the anayzed within 36 hours. Samping of iquid products shoud be performed whie the materia is in motion. 53