Milk Powder Manufacture Research Articles

Evaluating the effectiveness of minimum chlorate technologies employed by manufacturers of skim milk powder from both microbiological quality and chemical residue perspectives

Dairy processors in the Republic of Ireland have adopted chlorine-free chemicals for cleaning and chlorine gas for water disinfection as a means of minimizing chlorate residue in dairy products. For these "minimum chlorate technologies" to be satisfactory, they must be able to deliver product with acceptable levels of bacteria as well as minimum levels of chlorate and other chlorine-based residues. To establish the effectiveness of these technologies, sampling was conducted across the skim milk powder (SMP) manufacturing chain in 3 separate milk processing sites. Across the 3 sites a total of 11 different batches of SMP were sampled in duplicate from the whole milk silo through the manufacturing process to the powder product; yielding a total of 137 samples. Samples were tested for chlorate, perchlorate and trichloromethane alongside a suite of microbiological plate count tests including total bacteria, thermophilic bacteria, thermoduric bacteria and both mesophilic and thermophilic spore-forming bacteria. Chlorate was detected at reportable levels (≥0.01 mg/kg) in 9 of 22 SMP samples analyzed; resulting in a mean chlorate concentration 0.0183 mg/kg. Bacteria were ubiquitous across all samples analyzed with spore-forming bacteria counts ranging from 1.30 to 2.33 log cfu/g in SMP.

Detection of risk areas in dairy powder processes: The development of thermophilic spore forming bacteria taking into account their growth limits

Anoxybacillus flavithermus, Geobacillus stearothermophilus and Bacillus licheniformis are the main contaminants found in dairy powders. These spore-forming thermophilic bacteria, rarely detected in raw milk, persist, and grow during the milk powder manufacturing process. Moreover, in the form of spores, these species resist and concentrate in the powders during the processes. The aim of this study was to determine the stages of the dairy powder manufacturing processes that are favorable to the growth of such contaminants. A total of 5 strains were selected for each species as a natural contaminant of dairy pipelines in order to determine the minimum and maximum growth enabling values for temperature, pH, and aw and their optimum growth rates in milk. These growth limits were combined with the environmental conditions of temperature, pH and aw encountered at each step of the manufacture of whole milk, skim milk and milk protein concentrate powders to estimate growth capacities using cardinal models and the Gamma concept. These simulations were used to theoretically calculate the population sizes reached for the different strains studied at each stage in between two successive cleaning in place procedures. This approach highlights the stages at which risk occurs for the development of spore-forming thermophilic bacterial species. During the first stages of production, i.e. pre-treatment, pasteurization, standardization and pre-heating before concentration, physico-chemical conditions encountered are suitable for the development and growth of A. flavithermus, G. stearothermophilus and B. licheniformis. During the pre-heating stage and during the first effects in the evaporators, the temperature conditions appear to be the most favorable for the growth of G. stearothermophilus. The temperatures in the evaporator during the last evaporator effects are favorable for the growth of B. licheniformis. In the evaporation stage, low water activity severely limits the development of A. flavithermus.

Karakterisasi santan instan bubuk yang dibuat menggunakan filler Na-CMC dari bacterial cellulose

The development of the times demands the problem of food being available in a fast and ready-to-eat time, one of which is the problem of providing coconut milk. Making coconut milk during this time requires a long process and takes a long time. To answer this problem, instant coconut milk powder is the solution. This product has the advantages of long shelf life, easy packaging, easy storage and easy to transport due to reduced volume and weight. This study aims to determine the role of Sodium - Carboxymethyl Cellulose (Na-CMC) from bacterial cellulose as a filler in the manufacture of instant coconut milk powder combined with maltodextrin. The experimental design used in the study was a Single Factor Completely Randomized Design, the factor was the proportion between Na-CMC and Maltodextrin consisting of 4 levels of C1 (Na-CMC 0% : Maltodextrin 20%), C2 (Na-CMC 5% : Maltodextrin 15%), C3 (Na-CMC 10% : Maltodextrin 10%), C4 (Na-CMC 15% : Maltodextrin 5%), C5 (Na-CMC 20% : Maltodextrin 0%). Observed parameters of moisture content, fiber content and solubility. The results showed the highest water content of instant coconut milk powder in the C5 treatment (Na-CMC 20% : Maltodextrin 0%) of 11.51%, the highest fiber content of 0.34% in the C5 treatment (Na-CMC 20% : Maltodextrin 0%), while the solubility was highest in the C1 treatment (Na-CMC 0% : Maltodextrin 20%) of 40.50%.

The effect of homogenisation pressure on the microstructure of milk during evaporation and drying: particle-size distribution, electronic scanning microscopy, water activity and isotherm.

Homogenisation is a widely used technique in manufacturing powdered milk with a direct impact on product solubility, and the homogenisation pressure is a central attribute of this process. We aimed to understand the effect of increasing homogenisation pressures (0/0, 15/5, and 75/5 MPa, 1st/2nd stages) on particle-size distribution during homogenised whole milk powder manufacture and rehydration of the final product. The fluid milk was thermally treated, homogenised, concentrated by rotary evaporation, and then dried using a spray dryer. Particle size (Dv90) was monitored at all stages of the manufacturing process. The final product (milk powder) was analysed using particle-size distribution, electronic scanning microscopy, water activity, and isotherms. The results demonstrated that increasing the homogenisation pressure leads to milk powder with smaller particle size when rehydrated (Dv90 values: 6.08, 1.48 and 0.64 μm for 0, 20 and 80 MPa, respectively). Furthermore, the volume (%) of the particles in the 'sub-micro' region (smaller than 1.0 μm) presented an inversely proportional profile to the homogenisation pressure (homogenised fluid milk: 86.1, 29.3 and 2.4%; concentrated milk: 86.1, 26.5 and 5.7%, and reconstituted milk powder: 84.2, 31.8 and 10.9%). Surprisingly, this pattern was not observed in the SPAN value (which corresponds to the width or range of the size distribution based on the volume). Additionally, the increase in the homogenisation pressure did not affect the sorption isotherm pattern. These results demonstrate that increasing the homogenisation pressure decreases the particle size of the reconstituted powdered milk, indicating the potential for future studies on how this phenomenon affects its physicochemical and final product properties.

Stabilisation of evaporation and spray drying processes with municipal or reverse osmosis water as an entry point for chlorate during manufacture of skim milk powder

Chlorate is a concern in the food and beverage industry, associated with chlorine sanitisers in industrial processing and water treatment. This study monitored chlorate entry and accumulation points during skim milk evaporation and spray drying when using municipal and reverse osmosis water to stabilise processing equipment. Municipal water was associated with a 9.2 ± 1.7 and 6.6 ± 1.4 fold increase in chlorate on a dry matter basis during the initial transition from water to product for evaporation and spray drying, respectively. This was not observed when the equipment was stabilised with reverse osmosis water, but could vary depending on the time taken to stabilise processing equipment. Once equipment was in a steady state, there was no entry of chlorate into the finished product for processes stabilised using either water sources; the main points of concern are transitionary periods of operation linked to co-mixing of the product and water.

A process optimization approach for microwave vacuum drying of concentrated skim milk.

Microwave vacuum drying (MVD) of concentrated skim milk and its resulting powder properties have been studied to a very limited extent. To explore the potential of this technology for the manufacture of milk powder, MVD of concentrated skim milk (37.5% total solids) was evaluated with respect to product properties and drying efficiency. A custom factorial design was used to optimize drying parameters, which enabled us to find optimal drying conditions with a minimal number of drying experiments (16). Vacuum level (3.3-13.3 kPa), specific power input (0.86-1.72 W·g -1), and product layer thickness (1-4 mm) were studied as factors. Total drying time, product foaming at the beginning of the process, product temperature in the last drying interval, browning, insolubility index, and calculated product yield were used as responses to identify optimal MVD processing parameters. Optimal drying of concentrated skim milk that maximized yield and minimized drying time while maintaining good product quality was achieved at a layer thickness of 2 mm, pressure of 6.0 kPa, and a specific power input of 1.29 W·g -1. Under constant power output, layer thickness was found to be the most important processing parameter to control product temperature during the final drying stage. Maximum product temperatures below 55°C yielded powder with good solubility. The findings of this exploratory study for MVD of concentrated skim milk yield important information and guidelines for production of good quality milk powders or preservation of starter cultures in a dairy matrix such as infant formula.

Stabilisation of Evaporation and Spray Drying Processes with Municipal or Reverse Osmosis Water as an Entry Point for Chlorate During Manufacture of Skim Milk Powder

Stabilisation of Evaporation and Spray Drying Processes with Municipal or Reverse Osmosis Water as an Entry Point for Chlorate During Manufacture of Skim Milk Powder

Evaluation of potential methods to minimize solid loss during the manufacture of coconut milk powder

A coconut milk powder manufacturing plant encountered about 4.7% solid loss. This study was undertaken to identify measures to minimize this solid loss. Solid losses through different modes were quantified. Sample size for determination of total solid in coconut milk and conductivity cut-off point of the drain plate were optimized. Solid losses (kg run-1) through the dryer (2,954.6±106.2), drain plate (2,575.1±734.1) and due to over estimation of total solid in coconut milk (394.7±69.1) accounted for 46.5, 40.5 and 6.2% of the total solid loss, respectively. About 63% reduction in solid loss through the drain plate was evident when the conductivity cut-off point reduced from 4 to 1 mS cm-1. It was also revealed 92% reduction in over estimation of total solid when the sample size of coconut milk reduced from 2.0 to 1.5 g. In conclusion, sample size of 1.5 g for rapid total solid determination and 1 mS cm-1 conductivity cut-off point for the drain plate are recommended to minimize solid loss of this plant.

Improving quality of maintenance task for milk powder manufacturing unit through TOPSIS

PurposeThe purpose of this paper is to explore the possibilities of improving the quality of existing maintenance task of the atomizer of milk powder manufacturing unit of a dairy plant. Looking to the past business volume and expected growth, the milk powder manufacturing unit forms a noticeable sector of processing plant. The lack of quality in maintenance standards leads to reliability losses of about 20–25% with low productivity and profit. Such facts and challenges of keeping the system in ready-state motivate a definite maintenance plan to be modeled based on a live failure analysis to be executed during shutdown or scheduled period.Design/methodology/approachThe deliverables are achieved by collecting the historical failure data i.e. downtime and failure frequencies; from January 2020 to July 2020 at Dudhsagar dairy, Gujarat, India. Reliability modeling is done in a view to understand the failure pattern behavior of the milk powder manufacturing unit. The atomizer is discriminated as a critical component based on these data and their functional failures, failure causes, effects and repercussions of failures with existing control and maintenance practices has been modeled based on live shop-floor study. Scores are assigned on 1 to 10 levels by analyzing attributes effects from lowest to highest concern respectively for every modes of failure through realistic brain-storming among maintenance team by incorporating some advanced attributes like maintainability, economic safety, economic cost and spares with basic criteria in this study. The maintainability criticality index (MCI) is narrated by these score values through multi-attribute decision-making (MADM) based failure analysis models like Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS).FindingsThe primary findings of this research work are to propose improvements in the quality of the maintenance plan of critical component like; atomizer of a milk powder manufacturing unit which is commonly representing critical component in a major range of industrial processes. The case study recommended four silent maintenance strategies i.e. scheduled maintenance scheduled discard, scheduled failure finding and redesign as a qualified maintenance plan for the atomizer based on MCI and rankings of its potential failure causes. The results are helpful in upgrading quality standards for the maintenance activities of a process industry of alike or of dissimilar kinds in accordance with the failure analysis.Originality/valueOriginality mainly consists of investigating the scope of enhancing the existing maintenance practices through actual failure analysis with the help of TOPSIS. The criteria employed in this study are probability of chances of failure, degree of detectability and degree of severity as basic criteria along with some advanced criteria like; maintainability, spare parts, economic cost, economic safety are selected based on the outcome of shop-floor study and reliability modeling. The notable past failure statistics (downtime, frequency of failures) of a milk powder manufacturing unit were recorded and these data are analyzed based on reliability to extract an explicative component i.e. atomizer.

A Methodology for Industrial Water Footprint Assessment Using Energy-Water-Carbon Nexus

Recent national government policy in Ireland proposes a radical transformation of the energy sector and a large reduction in CO2 emissions by 2050. Water and energy form the water–energy nexus, with water being an essential component in energy production. However, the connection between the production of energy and water is rarely made. In particular, the end-user processes are generally excluded because they occur outside the water industry. The present study includes two simple approaches for industrial sites to calculate their carbon footprint in the water sector. The assessment of the milk powder manufacturing using both approaches indicates that the combined emission factor of the water supply and treatment is approximately 1.28 kg CO2 m−3 of water. The dairy production among steel, textile, and paper industries appears to be the most carbon-emitting industry. However, the results show that the carbon intensity of the water supply and treatment can be minimized by the integration of renewable energy sources for the onsite heat/steam and electricity generation. The uniqueness of our approaches compared to calculations illustrated by the ecoinvent and other governmental databases is its simplicity and a focus on the main energy consuming manufacturing steps in the entire industrial process. We believe that the management of water and energy resources will be more efficient when “active water citizens” raise environmental awareness through promoting measures regarding data monitoring and collection, observed leaks and damages, dissimilation and exchange of information on sustainable water stewardship to public and various industrial stakeholders.

Influence of the incubation temperature and total dissolved solids concentration on the biofilm and spore formation of dairy isolates of Geobacillus stearothermophilus.

Geobacillus species are an important contaminant in the dairy industry and their presence is often considered as an indicator of poor plant hygiene with the potential to cause spoilage. They can form heat resistant spores that adhere to surfaces of processing equipment and germinate to form biofilms. Therefore, strategies aimed towards preventing or controlling biofilm formation in the dairy industry are desirable. In this study we demonstrate that the preferred temperature for biofilm and spore formation among Geobacillus stearothermophilus A1, D1, P3 and ATCC 12980 was 65°C. Increasing the total dissolved milk solids concentration to 20% (w/v) caused an apparent delay in the onset of biofilm and spore formation to detectable concentrations among all the strains at 55°C. Compared to the onset time of the biofilm formation of A1 in 10% (w/v) reconstituted skim milk, addition of milk protein (whey protein and sodium caseinate) caused an apparent delay in the onset of biofilm formation to detectable concentrations by an average of 10 h at 55°C. This study proposes that temperature and total dissolved solids concentration have a cumulative effect on the biofilm and spore formation of G. stearothermophilus A1, D1, P3 and ATCC 12980. In addition, the findings from this study may indicate that preconditioning of stainless-steel surface with adsorbed milk proteins may delay the onset of biofilm and spore formation of thermophilic bacteria during milk powder manufacture.IMPORTANCE The thermophilic bacilli, Geobacillus stearothermophilus is a predominant spoilage bacterium in milk powder manufacturing plants. If their numbers exceed the accepted levels, this may incur financial loses by lowering the price of the end product. Furthermore, they can form heat resistant spores which adhere to processing surfaces and can germinate to form biofilms. Previously conducted research had highlighted the variation in the spore and biofilm formation among three specific strains of G. stearothermophilus isolated from a milk powder manufacturing plant in New Zealand. The significance of our research is demonstrating the effect of two abiotic factors namely temperature and total dissolved solids concentration on the biofilm and spore formation of these three dairy isolates, leading to modifications in the thermal processing steps aimed towards controlling the biofilm and spore formation of G. stearothermophilus in the dairy industry.

RAM assessment of the repairable industrial structure with genuine human-mistake working conditions with generalized fuzzy numbers

PurposeThe present paper investigated a skim milk powder production plant with genuine human mistake for analyzing its performance in terms of its reliability, availability and maintainability (RAM) indices along with mean time between failure (MTBF) and expected number of failure (ENOF).Design/methodology/approachIn the proposed work, the generalized fuzzy lambda–tau methodology has been used to carry out the analysis of the repairable structure using the improved arithmetic operations for generalized fuzzy numbers by considering the degree of confidence levels.FindingsRAM indices along with MTBF and ENOF are obtained to increase the quality of skim milk powder manufacturing structures of a dairy plant with genuine human-mistake working conditions.Originality/valueIn the present paper, a mathematical model for a complex industrial system based on fuzzy has been developed. Finally, the results are more realistic and comprehensive for the decision-maker for farther application.

Prevalence of Cronobacter spp. and Salmonella in Milk Powder Manufacturing Facilities in the United States

The U.S. Food and Drug Administration (FDA) conducted a sampling assignment in 2014 to ascertain the prevalence of Cronobacter spp. and Salmonella in the processing environment of facilities manufacturing milk powder. Cronobacter was detected in the environment of 38 (69%) of 55 facilities. The average prevalence of Cronobacter in 5,671 subsamples (i.e., swabs and sponges from different facility locations) was 4.4%. In the 38 facilities where Cronobacter was detected, the average prevalence of positive environmental subsamples was 6.25%. In 20 facilities where zone information of the sampling location was complete, Cronobacter was most frequently detected in zone 4, followed by zone 3, then zone 2, with zone 1 yielding the lowest percentage of positive samples. The prevalence of Cronobacter across the zones was statistically different (P < 0.05). There was no significant association between product type (i.e., lactose, whey products, buttermilk powder, and nonfat dried milk) and prevalence of Cronobacter in the facility. Salmonella was detected in the environment of three (5.5%) of the 55 facilities; all three facilities produced dried whey product. The overall prevalence of Salmonella in 5,714 subsamples was 0.16%. In facilities in which Salmonella was detected, the average prevalence was 2.5%. Salmonella was most frequently detected in zone 4, followed by zone 3. Salmonella was not detected in zone 1 or zone 2. The disparity between Salmonella and Cronobacter prevalence indicates that additional measures may be required to reduce or eliminate Cronobacter from the processing environment.

SIFAT FISIK, SIFAT ORGANOLEPTIK DAN AKTIVITAS ANTIOKSIDAN SUSU BUBUK KEDELAI HITAM BERDASARKAN KONSENTRASI TWEEN 80

Soy milk is one alternative to cow's milk for lactusa intolerance patients. The utilization of black soy less is attention and not as popular as yellow soybean because of the color that is less interesting. Another alternative in the processing of milk is the manufacture of milk powder. Processing of instant soy milk powder using foam-mat drying method required addition of filler material ie maltodextrin and Tween 80. With the addition of proper Tween 80 concentration expected to produce more stable milk powder. The general purpose of this research is to know the effect of Tween 80 concentration variation on physical properties, organoleptic properties and antioxidant activity of black soybean milk powder. Experimental method of experimental type using Completely Randomized Design (RAL) monofactor with Factor addition of Tween 80 concentration (0, 0,25, 0,5, 0,75 and 1 percent). The product analyzed physical properties (water absorption, moisture content, solubility and settling rate), organoleptic properties and antioxidant activity. The best result of antioxidant activity was 33,70% RSA at concentration 0,25%, water absorption 2,77 ml / g at concentration 0,25%, water content, 8,98% at concentration 0,25%, solubility 84,435% at a concentration of 0.75% and a precipitation rate of 10 s at a concentration of 0.25%. While the best organoleptic test is at concentration 0.25%. The conclusions of the research on black soybean milk powder with the addition of Tween 80 concentration showed a real difference for each test conducted where black soybean milk powder with the addition of Tween 80 0.25% concentration was the best treatment.

Changes in bioactive milk serum proteins during milk powder processing

This study mainly investigated changes in milk serum proteins by simulating the industrial processing of whole milk powder using a label-free proteomic approach. A total of 391 proteins were identified, 89 of which were quantified in all groups. Compared with raw milk, the milk subjected to the heating pasteurization process showed significantly decreased the serum protein profile, whereas that subjected to vacuum concentration and spray-drying showed minimal changes. The LC-MS/MS results were further confirmed by determining the activity of bioactive xanthine oxidase and retention of lactoferrin and immunoglobulins. The data showed that 70%–85% of lactoferrin and immunoglobulins were retained in vacuum-concentrated or spray-dried milk but were hardly identifiable in heat-pasteurized milk or whole milk powders. These findings indicate the need for improving the current milk powder-manufacturing techniques to allow the retention of active milk proteins.

Monitoring residue concentrations in milk from farm and throughout a milk powder manufacturing process.

The experiments reported in this research paper aimed to investigate differences in the levels of chlorate (CHLO), perchlorate (PCHLO), trichloromethane (TCM) and iodine residues in bulk tank (BT) milk produced at different milk production periods, and to monitor those levels throughout a skim milk powder (SMP) production chain (BTs, collection tankers [CTs], whole milk silo [WMS] and skim milk silo [SMS]). Chlorate, PCHLO and iodine were measured in SMP, while TCM was measured in the milk cream. The CHLO, TCM and iodine levels in the mid-lactation milk stored in the WMS were lower than legislative and industrial specifications (0.0100 mg/kg, 0.0015 mg/kg and 150 µg/l, respectively). However, in late-lactation, these levels were numerically higher than the mid-lactation levels and specifications. Trichloromethane accumulated in the cream portion after separation. Perchlorate was not detected in any of the samples. Regarding iodine, the levels in mid-lactation reconstituted SMP were higher than that required by manufacturers (100 µg/l), indicating that the levels in milk should be lower than 142 µg/l. The higher residue levels observed in late-lactation could be related to the low milk volume produced during that period and changes in sanitation practices, while changes in feed management could have affected iodine levels. This study could assist in controlling and setting limits for CHLO, TCM and iodine levels in milk, ensuring premium quality dairy products.

Evaluation and validation of an inline Coriolis flowmeter to measure dynamic viscosity during laboratory and pilot-scale food processing

Abstract Inline process analytical technology tools are increasingly employed in industry as they facilitate real time process parameter monitoring and optimization of product quality. Use of an inline viscometer in milk powder manufacture allows greater process control by monitoring the dynamic viscosity of the process concentrate pumped to the spray drier. In this study, an inline Promass I300 was used to measure the dynamic viscosity of both a Newtonian fluid (10–60% w/w sucrose solutions) and a non-Newtonian fluid (10–40% w/w skim milk concentrate) at laboratory scale at 25 °C. Validation of the instrument for measurement of a non-Newtonian fluid was completed at pilot-scale under similar operating conditions. Coefficient of determination (R2 = 0.99) was obtained between inline and offline viscosity measurements for both Newtonian and non-Newtonian fluids investigated. This study demonstrated the potential of an inline Coriolis flowmeter for rapid and accurate measurement of dynamic viscosity during processing of dairy streams. Industrial relevance Control of milk concentrate viscosity during the manufacture of milk powder is critical to reduce energy consumption, reduce fouling and meet powder functional properties e.g. dispersability, flowability, particle size and powder hydration. The use of inline instruments for continuous monitoring of viscosity offers economic benefits to the producer as it can contribute to reduction in commonly encountered process issues such as fouling, blocking of nozzles and evaporator, which can result in process downtime and in extreme cases, product rework. Inline instruments can thus be employed to improve process control and reduce production waste during the manufacture of dairy powders.

Microbiological quality of milk from farms to milk powder manufacture: an industrial case study.

The experiments reported in this research paper aimed to track the microbiological load of milk throughout a low-heat skim milk powder (SMP) manufacturing process, from farm bulk tanks to final powder, during mid- and late-lactation (spring and winter, respectively). In the milk powder processing plant studied, low-heat SMP was produced using only the milk supplied by the farms involved in this study. Samples of milk were collected from farm bulk tanks (mid-lactation: 67 farms; late-lactation: 150 farms), collection tankers (CTs), whole milk silo (WMS), skim milk silo (SMS), cream silo (CS) and final SMP. During mid-lactation, the raw milk produced on-farm and transported by the CTs had better microbiological quality than the late-lactation raw milk (e.g., total bacterial count (TBC): 3.60 ± 0.55 and 4.37 ± 0.62 log 10 cfu/ml, respectively). After pasteurisation, reductions in TBC, psychrotrophic (PBC) and proteolytic (PROT) bacterial counts were of lower magnitude in late-lactation than in mid-lactation milk, while thermoduric (LPC-laboratory pasteurisation count) and thermophilic (THERM) bacterial counts were not reduced in both periods. The microbiological quality of the SMP produced was better when using mid-lactation than late-lactation milk (e.g., TBC: 2.36 ± 0.09 and 3.55 ± 0.13 cfu/g, respectively), as mid-lactation raw milk had better quality than late-lactation milk. The bacterial counts of some CTs and of the WMS samples were higher than the upper confidence limit predicted using the bacterial counts measured in the farm milk samples, indicating that the transport conditions or cleaning protocols could have influenced the microbiological load. Therefore, during the different production seasons, appropriate cow management and hygiene practices (on-farm and within the factory) are necessary to control the numbers of different bacterial groups in milk, as those can influence the effectiveness of thermal treatments and consequently affect final product quality.

Life cycle assessemnt (LCA) study of a milk powder product in aluminium foil packaging

Dairy processing industry is one of the industries that give positive contribution to the economic growth, however it also contributes in many impacts on the environment, as well as milk powder product manufactured by PT X. The main objective of this study was to determine the most significant environmental impact caused by production and transportation of milk powder in bag 250 gram (Product X) using Life Cycle Assessment (LCA) methodology. The boundary of the LCA study is “cradle to gate”, including: materials production, materials transportation from supplier to the PT X factory, manufacture of milk powder in PT X, and distribution of the products from factory to distributor. Four impact categories will be calculated on this study: global warming potential (GWP), eutrophication potential (EP), acidification potential (AP), and photochemical oxidant creation potential (POCP). The impact assessment was calculated by software SimaPro v.8.3.2 faculty license, and the calculation result validated manually by Microsoft Excel. The result of environmental impact calculation showed the GWP, EP, AP, and POCP of 1 kg milk powder is 1.3245 kg CO2 eq/kg, 0.0033 kg PO43- eq/kg, 0.0066 kg SO2 eq/kg and 0.0020 kg C2H4 eq/kg. The material production subsystem has the highest environmental impact on GWP, POCP, AP and EP categories. In particular, production activity in PT X also contributes to GWP. An environmental impact reduction strategy can focus on reducing GWP with electricity usage efficiency and developing a material supplier selection plan with environmental impacts of material production as one of criteria.

Nitrite production by thermophilic aerobic bacteria isolated during the manufacture of milk powder

Nitrite contamination in milk powder is hypothesised to be caused by thermophilic bacteria that form biofilms in milk powder manufacturing plants. Regulatory limits in some countries have made nitrite contamination in milk powder an issue influencing product sales. In this study, thermophilic bacteria were isolated from milk samples obtained from a milk processing plant to investigate the potential of different isolates to convert nitrate to nitrite. Eight bacteria species were identified through 16s rDNA gene sequencing (Bacillus licheniformis, Bacillus aerius, Bacillus subtilis, Bacillus sonorensis, Bacillus firmus, Enterococcus faecium, Geobacillus stearothermophilus and Macrococcus caseolyticus). Most bacteria isolated were able to convert nitrate to nitrite, and surprisingly in aerobic conditions. The most interesting species was G. stearothermophilus as its nitrate reducing capability was highly variable between different isolates. This could explain why there was no relationship reported between nitrite level in milk powder and high thermophile count.