A fluorimetric method for determination ofPseudomonas fluorescensAR11 lipase in skim milk powder, whey powder and whey protein concentrate

1984 ◽  
Vol 51 (4) ◽  
pp. 623-628 ◽  
Author(s):  
Donald Stead
Keyword(s):  
Whey Protein ◽  
Lipolytic Activity ◽  
Sodium Taurocholate ◽  
Milk Powder ◽  
Skim Milk ◽  
Milk Proteins ◽  
Skim Milk Powder ◽  
Whey Protein Concentrate ◽  
Protein Concentrate ◽  
Whey Powder

SummaryA method which was developed for assaying the extracellular lipases of psychrotrophic bacteria in milk (Stead, 1983, 1984) and which uses the fluorogenic substrate 4-methylumbelliferyl oleate has been adapted for use with skim milk powder (SMP), whey powder (WP) and whey protein concentrate (WPC). A five-fold increase in the concentration of sodium taurocholate (NaTC), in the mixture of NaTC and cetyltrimethylammonium bromide needed to dissociate lipase from milk proteins, removed the excessive sensitivity of the assay to variations in the concentrations of SMP, WP or WPC incorporated. Commercially available pancreatic lipase provided a suitable standard of lipolytic activity and as little as 1–2 μ could be detected in each assay system.

scholarly journals Karakteristik Fisikokimia Yogurt Tanpa Lemak dengan Penambahan Whey Protein Concentrate dan Gum Xanthan

2018 ◽  
Vol 38 (2) ◽  
pp. 178
Author(s):  
Mohamad Djali ◽  
Syamsul Huda ◽  
Lovita Andriani
Keyword(s):  
Whey Protein ◽  
Block Design ◽  
Milk Powder ◽  
Skim Milk ◽  
Chemical Properties ◽  
Skim Milk Powder ◽  
Whey Protein Concentrate ◽  
Protein Concentrate ◽  
Randomized Block Design ◽  
Physical And Chemical

Non-fat yogurt exhibited weak body, poor texture, and whey separation because of reduction of fat. The separation of whey in yogurt is not desired by consumer. The aim of present study was to evaluate the effect of adding whey protein concentrate (WPC) and xanthan gum on physical, chemical and sensory properties of non-fat yogurt. Physical and chemical properties were tested using randomized block design whereas the yogurts properties during 21 days of cold storage included syneresis index and organoleptic. There were 6 treatments : A (full fat yogurt = control 1); B (skim milk + skim milk powder (SMP) 3% = control 2); C (skim milk + SMP 3% + WPC 1%); D (skim milk + SMP 3% + WPC 1,25%); E (skim milk + SMP 3% + WPC 0,5% + xanthan 0,005%); F (skim milk + SMP 3% + WPC 0,5% + xanthan 0,004%). The fat content 0,12%-0,14% of non-fat yogurt with the addition of WPC and blend of WPC-xanthan could increased firmness, cohesiveness and consistency compared to control 1 and control 2. In the organoleptic properties, non-fat yogurt with the addition of WPC and blend of WPC-xanthan were gained color, flavor, aroma, and consistency of the panelists preferred higher than control yogurt. Non-fat yogurt with only addition of WPC gained the lowest syneresis index. ABSTRAKYogurt tanpa lemak memiliki kekuatan struktur yang rendah dan rentan terjadi pemisahan whey karena berkurangnya kandungan lemak. Pemisahan whey pada yogurt tidak disukai oleh konsumen. Tujuan penelitian ini adalah untuk mengevaluasi efek penambahan whey protein concentrate (WPC) dan gum xanthan terhadap karakteristik fisik, kimia sensori yogurt tanpa lemak. Karakteristik fisik dan kimia diuji menggunakan metode RAK, sedangkan karakteristik yogurt selama penyimpanan dingin 21 hari meliputi indeks sineresis dan organoleptik. Terdapat 6 perlakuan yaitu: A (susu segar = kontrol 1); B (susu skim + skim milk powder (SMP) 3% = kontrol 2); C (susu skim + SMP 3% + WPC 1%); D (susu skim + SMP 3% + WPC 1,25%); E (susu skim + SMP 3% + WPC 0,5% + gum xanthan 0,005%); F (susu skim + SMP 3% + WPC 0,5% + gum xanthan 0,004%). Kandungan lemak 0,12%-0,14% pada yogurt tanpa lemak dengan penambahan WPC dan kombinasi WPC-gum xanthan dapat meningkatkan firmness, cohesiveness, dan konsistensi dibandingkan kontrol 1 dan kontrol 2. Secara organoleptik, yogurt tanpa lemak dengan penambahan WPC dan kombinasi WPC-gum xanthan mendapatkan tingkat kesukaan panelis lebih tinggi untuk warna, rasa, aroma, dan kekentalan dibandingkan yogurt lemak utuh tanpa perlakuan. Yogurt tanpa lemak dengan penambahan WPC saja mendapatkan indeks sineresis lebih rendah dibandingkan perlakuan lainnya.

scholarly journals Quality properties of non-fat yogurt with addition of whey protein concentrate

2007 ◽  
Vol 23 (5-6-1) ◽  
pp. 291-299 ◽  
Author(s):  
M. Sady ◽  
J. Domagała ◽  
T. Grega ◽  
D. Najgebauer-Lejko
Keyword(s):  
Whey Protein ◽  
Milk Powder ◽  
Skim Milk ◽  
Storage Period ◽  
Skim Milk Powder ◽  
Whey Protein Concentrate ◽  
Protein Concentrate ◽  
Quality Properties ◽  
Sensory Score ◽  
Ph Level

The aim of the study was investigation of quality of fat-free, settype yoghurt made at 5% (w/w) protein level with addition of skim milk powder (SMP) and whey protein concentrate (WPC) blends. The ratio SMP/WPC in used blends was: 1/0; 2/1; 1/2; 0/1. On 1st, 7th and 21st day of refrigerated storage yoghurt was analysed for sensory properties, titrable acidity, pH, free fatty acids (FFA), acetaldehyde, and diacethyl. Also enumeration of viable L. delbrueckii ssp. bulgaricus and S. thermophilus was carried out. During the whole storage period products with SMP/WPC ratio at 1/2 and 2/1 obtained the best sensory score. Addition of WPC to yoghurt significantly decreased lactic acid concentration which positively influenced its stability during shelf life. It was shown that during storage acidity of yoghurt was growing up in concern of pH level. The acetaldehyde content tended to increase significantly in the yoghurt fortified with higher proportion of WPC opposite to diacethyl level which was the lowest in yoghurt with an SMP/WPC addition at 0/1. During storage concentration of both volatile compounds were the highest on 7th day and the lowest on 21st day. The maximum concentration of FFA was stated in products with SMP/WPC ratio 1/2. During the storage period FFA content significantly increased after 7th days and had no changed during next 14 days. The total number of yoghurt bacteria during the whole storage time was up to 1010 and did not vary depending on SMP/WPC ratio. Amount of L. delbrueckii ssp. bulgaricus was about one log cycle lower than S. thermophilus in all kinds of yoghurt.

Comparison of heat and pressure treatments of skim milk, fortified with whey protein concentrate, for set yogurt preparation: effects on milk proteins and gel structure

2000 ◽  
Vol 67 (3) ◽  
pp. 329-348 ◽  
Author(s):  
ERIC C. NEEDS ◽  
MARTA CAPELLAS ◽  
A. PATRICIA BLAND ◽  
PRETIMA MANOJ ◽  
DOUGLAS MACDOUGAL ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Whey Protein ◽  
Skim Milk ◽  
Milk Proteins ◽  
Whey Protein Concentrate ◽  
Protein Concentrate ◽  
Casein Micelles ◽  
Micelle Structure ◽  
Dynamic Structures ◽  
Β Lactoglobulin

Heat (85 °C for 20 min) and pressure (600 MPa for 15 min) treatments were applied to skim milk fortified by addition of whey protein concentrate. Both treatments caused > 90% denaturation of β-lactoglobulin. During heat treatment this denaturation took place in the presence of intact casein micelles; during pressure treatment it occurred while the micelles were in a highly dissociated state. As a result micelle structure and the distribution of β-lactoglobulin were different in the two milks. Electron microscopy and immunolabelling techniques were used to examine the milks after processing and during their transition to yogurt gels. The disruption of micelles by high pressure caused a significant change in the appearance of the milk which was quantified by measurement of the colour values L*, a* and b*. Heat treatment also affected these characteristics. Casein micelles are dynamic structures, influenced by changes to their environment. This was clearly demonstrated by the transition from the clusters of small irregularly shaped micelle fragments present in cold pressure-treated milk to round, separate and compact micelles formed on warming the milk to 43 °C. The effect of this transition was observed as significant changes in the colour indicators. During yogurt gel formation, further changes in micelle structure, occurring in both pressure and heat-treated samples, resulted in a convergence of colour values. However, the microstructure of the gels and their rheological properties were very different. Pressure-treated milk yogurt had a much higher storage modulus but yielded more readily to large deformation than the heated milk yogurt. These changes in micelle structure during processing and yogurt preparation are discussed in terms of a recently published micelle model.

scholarly journals Viability and growth promotion of starter and probiotic bacteria in yogurt supplemented with whey protein hydrolysate during refrigerated storage

2017 ◽  
Vol 71 (0) ◽  
pp. 0-0 ◽  
Author(s):  
Anna Dąbrowska ◽  
Konrad Babij ◽  
Marek Szołtysik ◽  
Józefa Chrzanowska
Keyword(s):  
Whey Protein ◽  
Growth Promotion ◽  
Protein Hydrolysate ◽  
Milk Powder ◽  
Skim Milk ◽  
Whey Protein Concentrate ◽  
Protein Concentrate ◽  
Bifidobacterium Adolescentis ◽  
Initial Stage ◽  
Whey Protein Hydrolysate

The effect of whey protein hydrolysate (WPH) addition on growth of standard yoghurt cultures and Bifidobacterium adolescentis during co-fermentation and its viability during storage at 4ºC in yoghurts has been evaluated. WPH was obtained with the use of serine protease from Y. lipolytica yeast. Stirred probiotic yoghurts were prepared by using whole milk standardized to 16% of dry matter with the addition of either whey protein concentrate, skim milk powder (SMP), WPH-SMP (ratio 1:1), WPH. The hydrolysate increased the yoghurt culture counts at the initial stage of fermentation and significantly inhibited the decrease in population viability throughout the storage at 4ºC in comparison to the control. The post-fermentation acidification was also retarded by the addition of WPH. The hydrolysate did not increase the Bifidobacterium adolescentis counts at the initial stage. However, the WPH significantly improved its viability. After 21 days of storage, in the yogurts supplemented with WPH, the population of these bacteria oscillated around 3.04 log10 CFU/g, while in samples where SMP or whey protein concentrate was used, the bacteria were no longer detected.

scholarly journals Mutu Keju Putih Rendah Lemak Diproduksi Dengan Bahan Baku Susu Modifikasi

2016 ◽  
Vol 40 (2) ◽  
pp. 144 ◽  
Author(s):  
Abubakar Abubakar
Keyword(s):  
Whey Protein ◽  
Milk Fat ◽  
Dry Matter ◽  
Corn Oil ◽  
Skim Milk ◽  
Raw Material ◽  
Whey Protein Concentrate ◽  
Protein Concentrate ◽  
Water Emulsion ◽  
White Cheese

This research was conducted to investigate the quality of low-fat white cheese produced using raw material of modified milk. Five treatments applied were (A1) Using reduced fat (60%) milk, (A2) Using emulsion of corn oil in skim milk (replacing milk fat with corn oil), (A3) Using emulsion of corn oil in skim milk and addition of whey protein concentrate (replacing milk fat with corn oil and the addition of whey protein concentrate=WPC), (A4) Using skim milk and water emulsion oil in water, and (A5) replacing milk fat with corn oil and the addition of probiotic (Lactobacillus casei). Each treatment was replicated three times. The selected that skim milk in corn oil emulsion with the addition of probiotics, the results showed had cheese quality characteristics as follow: yield 12.94±0.16%, hardnes 48.07±10.12 g, softness 8.51±0.54 kg/s, moisture content 50.37±1.60%, ash content 7.38±1.75% (dry matter), fat content 41.06±6.07% (dry matter), protein content 37.85±3.25% (dry matter), phosphorus content 346.62±25.61 mg/100g (dry matter), calcium content 860.78±87.91 mg/100g (dry matter), white color, regular texture, not flavorfull, salty taste, soft texture, elastic, ordinary preference acceptance.

Determination of Aflatoxin M1 in Liquid Milk, Cheese, and Selected Milk Proteins by Automated Online Immunoaffinity Cleanup with Liquid Chromatography‒Fluorescence Detection

2020 ◽  
Author(s):  
Jackie E Wood ◽  
Brendon D Gill ◽  
Harvey E Indyk ◽  
Ria Rhemrev ◽  
Monika Pazdanska ◽  
...  
Keyword(s):  
Whey Protein ◽  
High Throughput ◽  
Milk Proteins ◽  
Whey Protein Concentrate ◽  
Aflatoxin M1 ◽  
Protein Concentrate ◽  
Compliance Testing ◽  
Liquid Milk ◽  
Hydroxylated Metabolite ◽  
Single Laboratory

Abstract Background Aflatoxins are secondary metabolites produced by a number of species of Aspergillus fungi. Aflatoxin M1 (AFM1) is a hydroxylated metabolite of aflatoxin B1 and is found in the milk of cows fed with feed spoilt by Aspergillus species. AFM1 is carcinogenic, especially in the liver and kidneys, and mutagenic, and is also an immunosuppressant in humans. Objective A high-throughput method for the quantitative analysis of AFM1 that is applicable to liquid milk, cheese, milk protein concentrate (MPC), whey protein concentrate (WPC), whey protein isolate (WPI), and whey powder (WP) was developed and validated. Method AFM1 in cheese, milk, and protein products is extracted using 1% acetic acid in acetonitrile with citrate salts. The AFM1 in the resulting extract is concentrated using RIDA®CREST/IMMUNOPREP® ONLINE cartridges followed by quantification by HPLC‒fluorescence. Results The method was shown to be accurate for WP, WPC, WPI, MPC, liquid milk, and cheese, with acceptable recovery (81–112%) from spiked samples. Acceptable precision for WP, WPC, WPI, MPC, liquid milk, and cheese was confirmed, with repeatabilities of 4–12% RSD and intermediate precisions of 5–13% RSD. Method detection limit and ruggedness experiments further demonstrated the suitability of this method for routine compliance testing. An international proficiency scheme (FAPAS) cheese sample showed that this method gave results that were comparable with those from other methods. Conclusions A method for high-throughput, routine testing of AFM1 is described. The method was subjected to single-laboratory validation and was found to be accurate, precise, and fit-for-purpose. Highlights An automated online immunoaffinity cleanup HPLC‒fluorescence method for milk proteins, cheese, and milk was developed and single-laboratory validated. It allows for high-throughput analysis of AFM1 and can be used for the analysis of AFM1 in whey protein products.

scholarly journals Development and Validation of a Method for the Quantification of Milk Proteins in Food Products Based on Liquid Chromatography with Mass Spectrometric Detection

2011 ◽  
Vol 94 (4) ◽  
pp. 1043-1059 ◽  
Author(s):  
Petra Lutter ◽  
Véronique Parisod ◽  
Hans Weymuth
Keyword(s):  
Milk Powder ◽  
Skim Milk ◽  
Internal Standard ◽  
Milk Proteins ◽  
Skim Milk Powder ◽  
Selected Reaction Monitoring ◽  
Validation Data ◽  
Development And Validation ◽  
Protein Rich ◽  
Β Lactoglobulin

Abstract The protection of allergic consumers is crucial to the food industry. Therefore, accurate methods for the detection of food allergens are required. Targeted detection of selected molecules by MS combines high selectivity with accurate quantifcation. A confrmatory method based on LC/selected reaction monitoring (SRM)-MS/MS was established and validated for the quantifcation of milk traces in food. Tryptic peptides of the major milk proteins β-lactoglobulin, β-casein, αS2-casein, and κ-casein were selected as quantitative markers. Precise quantifcation was achieved using internal standard peptides containing isotopically labeled amino acids. For each peptide, qualifer and quantifer fragments were selected according to Commission Decision 2002/657/EC. A simple sample preparation method was established without immunoaffnity or SPE enrichment steps for food matrixes containing different amounts of protein, such as baby food, breakfast cereals, infant formula, and cereals. Intermediate reproducibility, repeatability, accuracy, and measurement uncertainty were determined for each matrix. LOD values of 0.2–0.5 mg/kg, e.g., for β-lactoglobulin, were comparable to those obtained with ELISA kits. An LOQ of approximately 5 mg/kg, expressed as mass fraction skim milk powder, was validated in protein-rich infant cereals. The obtained validation data show that the described LC/SRM-MS/MS approach can serve as a confrmatory method for the determination of milk traces in selected food matrixes.

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