Application of ATP bioluminescence for evaluation of surface cleanliness of milking equipment

The ATP bioluminescence method was used to evaluate the cleanliness of milking equipment surfaces (teat cup rubbers, teat dip containers, milk receivers, and pipeline joints) in dairy farms in Galicia (northwest Spain) with parlour, pipeline tie-stall or bucket tie-stall milking systems. The cleanest surfaces were teat cup rubbers. The use of non-chlorinated water for cleaning, and of pipeline or bucket tie-stall milking systems, was associated with high ATP bioluminescence values. However, ATP bioluminescence values only explained 12% of the variability in bulk-tank bacterial count; this is attributable to the importance of other factors (notably the correct functioning of the tank cooling system) for maintenance of low bacterial count.     

Enhancing the bactericidal effect of electrolyzed water on Listeria monocytogenes biofilms formed on stainless steel

Biofilms are potential sources of contamination to food in processing plants, because they frequently survive sanitizer treatments during cleaning. The objective of this research was to investigate the combined use of alkaline and acidic electrolyzed (EO) water in the inactivation of Listeria monocytogenes biofilms on stainless steel surfaces. Biofilms were grown on rectangular stainless steel (type 304, no. 4 finish) coupons (2 by 5 cm) in a 1:10 dilution of tryptic soy broth that contained a five-strain mixture of L. monocytogenes for 48 h at 25 degrees C. The coupons with biofilms were then treated with acidic EO water or alkaline EO water or with alkaline EO water followed by acidic EO water produced at 14 and 20 A for 30, 60, and 120 s. Alkaline EO water alone did not produce significant reductions in L. monocytogenes biofilms when compared with the control. Treatment with acidic EO water only for 30 to 120 s, on the other hand, reduced the viable bacterial populations in the biofilms by 4.3 to 5.2 log CFU per coupon, whereas the combined treatment of alkaline EO water followed by acidic EO water produced an additional 0.3- to 1.2-log CFU per coupon reduction. The population of L. monocytogenes reduced by treatments with acidic EO water increased significantly with increasing time of exposure. However, no significant differences occurred between treatments with EO water produced at 14 and 20 A. Results suggest that alkaline and acidic EO water can be used together to achieve a better inactivation of biofilms than when applied individually.     

Adenosine triphosphate bioluminescence for hygiene testing of rubber liners and tubes on dairy farms

Prevention of biofilm formation in milking equipment is important to ensure good hygiene quality of raw milk. Key factors to achieving good results are a successful cleaning procedure and a method to check the cleanliness of milking equipment surfaces. Adenosine triphosphate bioluminescence is a fast and easy method for investigating bacterial contamination of surfaces. However, previous studies on the potential of ATP bioluminescence to assess the hygiene status of milking equipment have been hampered by lack of a validated test procedure. The aim of this work was therefore to establish a test procedure for assessing the cleanliness of milking equipment using ATP bioluminescence, and apply the method on-farm to study the hygiene status of aging rubber material in milking equipment. In developing the test procedure, the effects of sampling location in tubes and liners, sampling of dry versus wet barrels, milking point in the parlor, and acid or alkali detergent on ATP values were investigated. The results showed that, to obtain reproducible results, replicate sampling from the same milking points in the parlor is important. For milk tubes, samples should preferably be taken from the milk meter side, for liners on the inside of the barrel. For best results, sampling should be performed after use of alkali detergent. No beneficial effect was observed of sampling dry liner barrels, so sampling in the standardized test procedure is performed directly after cleaning. The standardized test procedure was used on 3 different commercial farms and sampling was initiated after replacement of old rubber parts. On one of the farms, additional sampling was performed to evaluate total bacteria count and determine the association with ATP level. The results suggest that, provided an efficient cleaning procedure is used, the hygiene quality of milking equipment can be maintained during the recommended lifetime of the rubberware. However, due to occasional variation in cleaning efficiency between milking points and liner barrels, random sampling on single occasions can lead to incorrect conclusions. Replicate sampling over time is therefore important for correct interpretation of ATP bioluminescence data. If ATP levels are very high, complementary sampling for total bacteria count should be used to verify that the level is due to bacterial contamination, and not other organic ATP-contributing material (e.g., milk residues).     

Influence of the pre-rinse on the efficiency of circulation cleaning milking machines

The effect of volume and temperature of pre-rinse water on the cleaning efficiency of five circulation cleaned recorder milking machines was investigated. A hot (> 75 °C) pre-rinse gave the lowest bacteriological rinse total colony counts. As the rinse count differences were small, the least expensive cold water pre-rinse is considered satisfactory for most farms. A pre-rinse volume of 16 litres per unit removed more residual milk than eight litres per unit but gave no significant difference in rinse counts. For most plants 8–10 litres per unit is considered a satisfactory pre-rinse volume     

Milking system and premilking routines have a strong effect on the microbial community in bulk tank milk

In this study, we investigated the variation in the microbial community present in bulk tank milk samples and the potential effect of different farm management factors. Bulk tank milk samples were collected repeatedly over one year from 42 farms located in northern Sweden. Total and thermoresistant bacteria counts and 16S rRNA gene-based amplicon sequencing were used to characterize microbial community composition. The microbial community was in general heterogeneous both within and between different farms and the community composition in the bulk tank milk was commonly dominated by Pseudomonas, Acinetobacter, Streptococcus, unclassified Peptostreptococcaceae, and Staphylococcus. Principal component analysis including farm factor variables and microbial taxa data revealed that the microbial community in milk was affected by type of milking system. Milk from farms using an automatic (robot) milking system (AMS) and loose housing showed different microbial community composition compared with milk from tiestall farms. A discriminant analysis model revealed that this difference was dependent on several microbial taxa. Among farms using an automatic milking system, there were further differences in the microbial community composition depending on the brand of the milking robot used. On tiestall farms, routines for teat preparation and cleaning of the milking equipment affected the microbial community composition in milk. Total bacteria count (TBC) in milk differed between the farm types, and TBC were higher on AMS than tiestall farms (log 4.05 vs. log 3.79 TBC/mL for AMS and tiestalls, respectively). Among tiestall farms, milk from farms using a chemical agent in connection to teat preparation and a more frequent use of acid to clean the milking equipment had lower TBC in milk, than milk from farms using water for teat preparation and a less frequent use of acid to clean the milking equipment (log 3.68 vs. 4.02 TBC/mL). There were no significant differences in the number of thermoresistant bacteria between farm types. The evaluated factors explained only a small proportion of total variation in the microbiota data, however, despite this, the study highlights the effect of routines associated with teat preparation and cleaning of the milking equipment on raw milk microbiota, irrespective of type of milking system used.     

Water use on nonirrigated pasture-based dairy farms: Combining detailed monitoring and modeling to set benchmarks

Water use in intensively managed, confinement dairy systems has been widely studied, but few reports exist regarding water use on pasture-based dairy farms. The objective of this study was to quantify the seasonal pattern of water use to develop a prediction model of water use for pasture-based dairy farms. Stock drinking, milking parlor, and total water use was measured on 35 pasture-based, seasonal calving dairy farms in New Zealand over 2 yr. Average stock drinking water was 60 L/cow per day, with peak use in summer. We estimated that, on average, 26% of stock drinking water was lost through leakage from water-distribution systems. Average corrected stock drinking water (equivalent to voluntary water intake) was 36 L/cow per day, and peak water consumption was 72 L/cow per day in summer. Milking parlor water use increased sharply at the start of lactation (July) and plateaued (August) until summer (February), after which it decreased with decreasing milk production. Average milking parlor water use was 58 L/cow per day (between September and February). Water requirements were affected by parlor type, with rotary milking parlor water use greater than herringbone parlor water use. Regression models were developed to predict stock drinking and milking parlor water use. The models included a range of climate, farm, and milk production variables. The main drivers of stock drinking water use were maximum daily temperature, potential evapotranspiration, radiation, and yield of milk and milk components. The main drivers for milking parlor water use were average per cow milk production and milking frequency. These models of water use are similar to those used in confinement dairy systems, where milk yield is commonly used as a variable. The models presented fit the measured data more accurately than other published models and are easier to use on pasture-based dairy farms, as they do not include feed and variables that are difficult to measure on pasture-based farms.     

Use of Electrolyzed Oxidizing Water for Quality Improvement of Frozen Shrimp

The bactericidal effect of electrolyzed oxidizing (EO) water was evaluated on Escherichia coli O157:H7‐inoculated and Salmonella‐inoculated shrimp. The shrimp were inoculated on day 0 and stored frozen at ‐20°C. Bacterial enumeration was done on days 0, 24, 49, and 119 of frozen storage. Acidic EO water at 40 ppm free available chlorine was as effective as aqueous chlorine of the same concentration and was significantly more effective (P < 0.05) than tap water in reducing pathogen load on the inoculated shrimp. Further reduction of pathogen numbers was observed after each frozen storage period. Prewashing with alkaline EO water did not enhance the bactericidal activity of the acidic EO water on the shrimp. The washed acidic EO water of the inoculated shrimp had a nondetectable bacterial population compared with treated aqueous chlorine, alkaline EO water, and tap water. Non‐inoculated shrimp subjected to similar treatments were served cooked or uncooked to a minimum of 10 experienced panelists for sensory evaluation on days 0, 24, 49, and 119 of frozen storage. The cooked shrimp were evaluated for the presence of off‐odor, juiciness, tenderness, shrimpy flavor, aftertaste, and overall acceptability; whereas the raw shrimp were evaluated for color, firmness, presence of off‐odors, melanosis, and overall acceptability. Raw shrimp thawed from each frozen storage period were stored at refrigeration temperature (4 °C) for 3 d to observe for melanosis. No difference of sensory attributes was detected among the various treatment groups. Therefore, acidic EO water can be used as an effective disinfectant to replace aqueous chlorine for thawing shrimp blocks.     

Water changes in canned dry peas and beans during heat processing

The amount of water absorbed by dry peas ( Pissum sativum L. cv. 'Marrowfat') and dry beans ( Phaseolus vulgaris L. cv. 'Haricot') during soaking, blanching and canning was studied. The temperature during soaking significantly affected the water absorption rate up to 40 °C, but not beyond this temperature. The final water content of the product was significantly increased by blanching after soaking as opposed to blanching before soaking. Water uptake was also significantly affected by the water used. Total water uptake was about 150% greater in peas when soft water was used (60 °C). High soaking temperatures with correspondingly short soaking time (4 h at 60 °C) would be advantageous to a food manufacturer. Under these conditions, water absorption is increased in the finished product and the amount of product 'in process' is reduced, allowing a greater flexibility and control of the process.     

Effects of cleaning duration and water temperature on oxytocin release and milk removal in an automatic milking system

Four different methods of teat preparation during milking in an automatic milking system were studied in 2 experiments on Red Holstein/German Fleckvieh cross-breed cows. Milking routines used were milking: 1) without premilking teat preparation; 2) with one cleaning cycle (58 to 60 s) with cold (13 to 15 degrees C) water; 3) with one cleaning cycle with warm water (30 to 32 degrees C); or 4) with 2 cleaning cycles (122 s) with warm water. In experiment 1, milking characteristics were evaluated and milking routines were randomly assigned to 62 cows during 3 measuring periods of 24 h each. In experiment 2, 10 randomly selected cows were assigned to the same milking routines during 4 d and blood samples for oxytocin (OT) determination were taken during milking in addition to milk flow recording. Milk production, peak flow rate, total, and quarter milk yields showed no differences among treatments. Premilking preparation with cold water compared with warm water showed no differences in OT release, milk yield, peak flow rate, main milking time, average flow rate, or time until main milk flow. Baseline OT concentrations were consistently low. At the start of teat cup attachment without premilking teat preparation OT concentrations remained on the basal level but were elevated in all other treatments. By 30 s from the start of milking, OT concentrations were markedly increased in all treatments and were no longer different between treatments. In conclusion, the teat cleaning device used in the automatic milking system, either with warm or cold water, was suitable to induce milk ejection in cows before the start of milking.     

Parboiling of paddy by simple soaking in hot water

Parboiling of paddy by mere hot water soaking, without steaming, has the advantage of not requiring a boiler. Soaking at a temperature 10–15°C above the gelatinization temperature (i.e. generally at about 80–85°C) is necessary to achieve fair to moderate gelatinization (i.e. parboiling). However, soaking at such temperatures for a time sufficient for the water to penetrate and gelatinize the grain core invariably leads to over-imbibition of moisture, husk splitting and leaching; soaking for less time, on the other hand, leaves many grains with 'white belly'. The best method therefore is to soak the grain for such time as to imbibe about 30% moisture (wet basis) (i.e. for about 1 1/2–2 hr), drain out the water, and temper the hot paddy for another 1–2 hr. This process yields optimally parboiled paddy without 'white belly' or grain splitting and with reasonably good milling quality and colour.     

Efficacy of electrolyzed water in the inactivation of planktonic and biofilm Listeria monocytogenes in the presence of organic matter

The ability of electrolyzed (EO) water to inactivate Listeria monocytogenes in suspension and biofilms on stainless steel in the presence of organic matter (sterile filtered chicken serum) was investigated. A five-strain mixture of L. monocytogenes was treated with deionized, alkaline EO, and acidic EO water containing chicken serum (0, 5, and 10 ml/liter) for 1 and 5 min. Coupons containing L. monocytogenes biofilms were also overlaid with chicken serum (0, 2.5, 5.0, and 7.5 ml/liter) and then treated with deionized water, alkaline EO water, acidic EO water, alkaline EO water followed by acidic EO water, and a sodium hypochlorite solution for 30 and 60 s. Chicken serum decreased the oxidation-reduction potential and chlorine concentration of acidic EO water but did not significantly affect its pH. In the absence of serum, acidic EO water containing chlorine at a concentration of 44 mg/liter produced a > 6-log reduction in L. monocytogenes in suspension, but its bactericidal activity decreased with increasing serum concentration. Acidic EO water and acidified sodium hypochlorite solution inactivated L. monocytogenes biofilms to similar levels, and their bactericidal effect decreased with increasing serum concentration and increased with increasing time of exposure. The sequential 30-s treatment of alkaline EO water followed by acidic EO water produced 4- to 5-log reductions in L. monocytogenes biofilms, even in the presence of organic matter.     

An alternative heat treatment for milk pasteurization in Cameroon

In order to determine a suitable temperature and time combination for the proper pasteurization of milk under conditions in Cameroon, the destructive effects of heat on the peroxidase and micro-organisms in local milk were studied. In the first step, fresh milk samples were heated at temperatures of 64–100°C for 1 min. Peroxidase was found to be sensitive to heat treatment at temperatures of 74–76°C and completely destroyed above 78°C. In the second step, fresh milk samples were heated to 74°C and held at that temperature for 15 s, 5 min, 10 min, 15 min or 20 min; microbiological analyses revealed that survival rates were 56.7, 1.5, 0.2, 0.06 and 0.05%, respectively. Peroxidase was completely destroyed after 10 min at this temperature. In terms of microbial quality, there were no significant differences ( P  < 0.001) between holding times of 10, 15 and 20 min. A heat treatment of 74°C for 10 min yielded milk free of peroxidase and with < 10 000 cfu/mL. It is recommended that raw milk be given at least this treatment to ensure safe milk supplies in Cameroon.     

CLEANING AND DISINFECTION IN MILK PRODUCTION

Methods for reducing bacterial contamination derived from surfaces of cows' teats and milking equipment, the main sources of bacteria in raw milk, are described. Examples are given showing the effects of refrigerated storage on bacterial counts in raw milk. Costs of cleaning and prospects for cold cleaning and disinfection are considered.     

THE DEVELOPMENT OF AN IN-LINE REFRIGERATED MILK COOLER

A very simple but effective in-line cooler is described comprising a stainless steel coil which may be lowered into an agitated chilled water bath for cooling, or raised clear for washing.
The coil is easy to clean and may be used in conjunction with pipeline milking installations or with a dump station.
In the experimental prototype the milk cooling capacity was limited to 70 gal/day by the quantity of ice which could be stored, but this quantity of milk could be cooled from 35° to 2·8°C (95° to 37°F).
A simple insulated tank of 70 gal capacity has been constructed from which the milk can be collected in bulk; on test, the mean temperature rise of 70 gal water at 5°C (41 °F) was 1·5°C (2·7°F) in 8 h in an ambient temperature of 32°C (90°F). This tank could be trolley-mounted for roadside collection.     

A COMPARISON OF DIFFERENT METHODS OF CHEMICAL DISINFECTION OF FARM DAIRY UTENSILS

A comparison of separate and combined detergent disinfectant treatments of milk contact surfaces using an alkaline detergent and sodium hypochlorite was made by farm trials of naturally contaminated milking machine equipment and by laboratory soiled milking machine units. With six farms tested over a period of 3 months the combined treatment was superior and was still further improved by the addition of a sanitizing rinse immediately before milking. With laboratory soiled equipment there was no significant difference between the two methods, though the addition of a further sanitizing rinse to the combined method brought about a significant improvement. With the combined process the disinfectant rinse of 75 ppm hypochlorite exerted a greater disinfecting action than the hot detergent-disinfectant wash of 200 ppm hypochlorite. This appeared to be solely a result of the high pH of the alkaline wash. The importance of the sanitizing rinse immediately before milking was demonstrated, and its value attributed not to the concentration of disinfectant but to the timing of the rinse. Disinfectant rinses done several hours before milking (or bacteriological rinsing) allowed development of microorganisms on the utensil surface.     

Technical note: Effects of attachment of hind teats before cleaning and attachment of front teats on milking characteristics in automatic milking systems

Milking characteristics differ between the 4 quarters of a dairy cow udder. In particular, milking time is mostly prolonged in hind quarters compared with front quarters because of the usually higher amount of stored milk. The standard milking routine (STDMR) in both conventional and automatic milking systems (AMS) consists of teat preparation of all 4 quarters, followed by attachment of the 4 teat cups, regardless of the distribution of milk between quarters. In the current study, an alternative teat preparation and milking routine (ALTMR) in AMS was tested, which consisted of cleaning and starting the milking of hind teats before cleaning and attachment of front teats. The hypothesis was based on the fact that hind quarters have usually a longer milking time than front quarters. Starting the milking of hind quarters while the front teats are being cleaned may reduce the difference in the end of milking between front and hind quarters and thus reduce total milking time. Both routines were tested on 5 Swedish dairy farms equipped with AMS in a 4-wk experiment in which treatments were alternated weekly. Total milk yield did not differ between treatments. Machine-on time (MOT) was longer in ALTMR than in STDMR because the difference in milking time between hind and front quarters was less than the time needed to prepare the front teats. However, the longer MOT in ALTMR was compensated by a shorter total preparation time, including the attachment of the first teat cup, as only the hind teats (instead of all 4 teats) were cleaned before milking was started. This resulted in a similar total milking time from start of cleaning of the first quarter until the end of milking of the last quarter in both treatments. Because of the prolonged MOT, average milk flow rate was lower in ALTMR than STDMR. Peak flow rate was higher in ALTMR than STDMR, but only in teat cups 1 (first attached, hind quarter) and 3 (third attached, front quarter), whereas main milk flow was higher in ALTMR than STDMR in both front quarters. In conclusion, splitting teat cleaning and the start of milking between hind and front quarters does not prolong total milking time, including teat cleaning. The partially positive effect on peak and main milk flow indicates that the ALTMR is a suitable milking routine in AMS. In herds with a greater difference of milk stored in hind compared with front quarters, a reduced total milking time can be expected for ALTMR.     

No seasonal effect on culturable pseudomonads in fresh milks from cattle herds

Freshly drawn raw milk from 37 single herds on farms manufacturing raw cow cheese under the Protected Designation of Origin (PDO) label were sampled over 13 mo for pseudomonad counts. Coliforms, somatic cells, and coagulase-positive staphylococci were counted and total fat and protein contents measured. For pseudomonad counts, the overall mean value was 3.60×10(3) cfu/mL. We observed very high variation between different producers and within the same producers (average standard deviation 1.30×10(4) cfu/mL), but we did not detect a seasonal effect. The only statistical correlation with other milk quality parameters was with coliforms. A survey of milking practices and milking machine sanitation together with environmental and milk sampling for pseudomonad counts in 7 cheese workshops showed that no real negligence or error could be imputed to producers. The main problems were the presence of non-aeruginosa pseudomonads in potable water and a few isolated failures during the cleaning and rinsing phases of sanitation.     

LOW-TEMPERATURE DESTRUCTION OF Trichinella spiralis USING LIQUID NITROGEN AND LIQUID CARBON DIOXIDE

The destruction of Trichinella spiralis by low temperature treatment has been demonstrated to be an effective tool in combatting this parasite in fresh pork products. Current procedures, however, require a holding period under varying times and temperatures to accomplish this destruction. Freezing with cryogenic materials offers the opportunity to attain ultra low temperatures and, thus, eliminate post–freezing holding periods. Four trials were conducted using trichina-infected fresh pork patties approximately 9 mm thick and 88 mm square. In trials 1, 2 and 3 the patties were frozen with LN, using a modified Heath freezing tunnel to final equilibrated temperatures of –12C, –14°C, –20°C, –23°C, –25°C, –28°C, –29°C, –39°C and −47°C. In trial 4 the patties were frozen in a Certified Multideck tunnel using liquid CO₂ as a refrigerant to −10°C, –17°C, –23°C, –29°C and –39°C. Patties were thawed immediately and checked for viable T. spiralis. No positive samples were found at temperatures of –29°C or below.     

The effect of using nonchlorine products for cleaning and sanitising milking equipment on bacterial numbers and residues in milk

Seven milking machine cleaning procedures which differed in the working solution content of sodium hydroxide, presence of chlorine, temperature of water, and inclusion of acid and four antimicrobial products used as sanitisers in the premilking rinse water were evaluated. The cleaning system, which incorporated a high working solution of sodium hydroxide (2525 ppm) used in cold water combined with a hot (70 °C) daily acid wash, had lower total bacterial counts (TBC) (1040 colony forming units (cfu)/mL) than the same detergent product without the addition of acid (1980 cfu/mL) (P < 0.05). Lower TBC were observed in milk and on equipment surfaces when a sanitiser was applied (P < 0.01). Trichloromethane levels in milk were higher when chlorine was used as a sanitiser (P < 0.01).     

Instant infusion pasteurisation of bovine milk. I. Effects on bacterial inactivation and physical–chemical properties

Two types of milk, skim milk and non-standardised raw milk, were heat treated using direct heating by instant infusion pasteurisation with treatment temperatures in the range from 72°C to 120°C and with holding times of less than 1 second. Indirect heating by HTST pasteurisation (72°C for 15 seconds) was used for comparison. The inactivation of microorganisms reached at least the same level when using instant infusion pasteurisation compared to HTST pasteurisation. Changes in the physical-chemical properties were observed in the skim milk fractions of instant infusion pasteurised non-standardised milk, whereas for instant infusion pasteurised skim milk less influence from the treatments was observed.