693. A rejection test for raw milk

1958 ◽  
Vol 25 (1) ◽  
pp. 32-51 ◽  
Author(s):  
Peggy B. Taylor ◽  
L. F. L. Clegg
Keyword(s):  
Lactic Acid ◽  
Ferric Chloride ◽  
Technical Assistance ◽  
Milk Proteins ◽  
Raw Milk ◽  
Ph Change ◽  
Yellow Colour ◽  
A Value ◽  
Keeping Quality

The determination of apparent lactic acid has been used as a basis for a rejection test for raw milk. The method consists of precipitation of milk proteins with barium chloride, sodium hydroxide and zinc sulphate, and the addition of ferric chloride to the filtrate to produce the yellow colour of ferric lactate. Lactic acid is not solely responsible for the production of the yellow colour, which, nevertheless, gives a good relationship with keeping quality of milk (measured as hours to the C.O.B. end-point at 22° C.) and the values have been expressed as ‘apparent lactic acid’.The relationship of winter and summer milks to keeping quality has been studied, and a value of 0·03% apparent lactic acid in milk is equivalent to an average keeping quality of 5¾ and 8½ hr. for winter and summer milks, respectively. A value of 0·03% is recommended as the earliest value of apparent lactic acid at which milk could be rejected.The apparent lactic acid in colostrum and late-lactation milk and in milk from cows suffering from mastitis has been determined, and only in late-lactation milk were the values found to be significantly higher than usual in fresh raw milk, and an inverse relationship between yield and apparent lactic acid is suggested.Permanent glass matching disks have been prepared for use in a Lovibond comparator. This permits the intensity of the yellow colour produced with 1% ferric chloride to be determined and the apparent lactic acid in milk estimated.Grateful acknowledgement is made to the management and staff of the Dairy Department of the Reading Co-operative Society and the Farmer's Clean Milk Dairy, Reading, and local milk producers for supplying samples for experiments; to the N.M.T.S. staff in Reading for help in finding suitable farmers, and to the Dairy Husbandry Department of the N.I.R.D. for information about and samples of abnormal and late-lactation milk. Our particular thanks are due Miss Marie Gruber for technical assistance, to Dr N. J. Berridge for the suggestion and help on the work on pH change as an indication of keeping quality (given in the appendix), and to Dr A. T. R. Mattick for the advice given in this work.

scholarly journals Study on the Extension of Shelf-life by Activation of Inherent Lactoperoxidase System in Raw Cow Milk

2014 ◽  
Vol 7 ◽  
pp. 57-60
Author(s):  
Prashanta Pokhrel ◽  
Suman Kumar Lal Das
Keyword(s):  
Hydrogen Peroxide ◽  
Lactic Acid ◽  
Shelf Life ◽  
Room Temperature ◽  
Raw Milk ◽  
Potassium Thiocyanate ◽  
Cow Milk ◽  
Lactoperoxidase System ◽  
Keeping Quality

Effectiveness of lactoperoxidase in raw cow milk was studied to observe the increase in shelf-life. Lactoperoxidase system was activated within two hours after milking by the addition of hydrogen peroxide and potassium thiocyanate, then milk was kept at different conditions viz. refrigerated condition (5±2)°C, room temperature (25±3)°C and at (35±2)°C. The keeping quality of raw milk was determined by the acidity, which when reached 0.18 % as lactic acid, was considered spoiled. Results indicated that the lactoperoxidase system (LP-s) increased the shelf-life of raw cow milk kept at room temperature (25±3)°C and refrigeration temperature (5±2)°C significantly (p<0.05);however no significant increase in shelf-life was observed between the control and LP-s treated raw milk sample held at (35±2)°C. DOI: http://dx.doi.org/10.3126/jfstn.v7i0.10606   J. Food Sci. Technol. Nepal, Vol. 7 (57-60), 2012   

scholarly journals MAILLARD REACTIONS – AN IMPORTANT FACTOR OF THE SAFETY AND QUALITY OF INFANT FORMULA

2018 ◽  
Vol 63 (4) ◽  
pp. 30-42
Author(s):  
I. N. Skidan ◽  
C. Prosser ◽  
I. N. Zakharova
Keyword(s):  
Infant Formula ◽  
Milk Proteins ◽  
Goat Milk ◽  
Raw Milk ◽  
Biological Properties ◽  
Maillard Reaction Products ◽  
Powdered Infant Formula ◽  
Reaction Products ◽  
Maillard Reactions

The physicochemical properties of infant adapted milk formulae that affect their tolerability and effectiveness depend on the composition and quality of the raw ingredients, the production process, the storage conditions and the quality control of the finished products. The technology of manufacturing a powdered infant formula includes a variety of methodsfor processing componentsthat make up its composition, including raw milk. This processing is accompanied by a noticeable change in a number of physical, chemical and biological properties of the individual components of milk, their loss, the formation of fundamentally new chemical compounds. The most frequent reactions observed during the heat treatment of milk include the formation of bonds between reactive carbonyl groups of the sugar and the amino groups of amino acids, followed by the appearance of a large number of low- and high-molecular compounds, the so-called Maillard Reaction Products(MRP). The study of MRP in recent years hasincreasingly attracted the attention of medical practitioners because of the discovery of these compounds in infant formula and their potential danger to children’s health. This review provides evidence that powdered infant adapted formulae produced with an original technology based on whole goat milk with a native ratio of the main groups of milk proteins(whey – 20% and casein – 80%) have a minimum potential for unwanted effects associated with MRP.

Microbiological Conditions and Keeping Quality of Veal Tongues as Affected by Lactic Acid Decontamination and Vacuum Packaging

1988 ◽  
Vol 51 (3) ◽  
pp. 208-213 ◽  
Author(s):  
INGRID J. R. VISSER ◽  
PETER A. KOOLMEES ◽  
PETER G. H. BIJKER
Keyword(s):  
Lactic Acid ◽  
Tap Water ◽  
Treated Group ◽  
Vacuum Packaging ◽  
Delayed Effect ◽  
Veal Calf ◽  
Keeping Quality ◽  
Stratified Squamous Epithelium ◽  
Ice Water

The effect of a lactic acid decontamination treatment on the microbiological condition and keeping quality of veal calf tongues was assessed. Thirty tongues were collected 45 min post mortem. Ten were washed with tap water in a centrifuge, 10 were treated with 2.0% (v/v) L-lactic acid instead of water, and 10 tongues received no treatment and served as control samples. Immediately following these treatments all tongues were vacuum-packaged, chilled 2 h in ice-water and stored at 3±1 °C and 85±5 % ERH. At 0, 14, and 28 d postmortem samples were taken for bacteriological, histobacterioscopic and sensory examination. The histobacterioscopic examination showed that the initial microflora appeared to be predominantly located under and between the papillae of the tongue surface. Centrifugation with water only did not significantly affect the bacteriological condition of tongues, although the overall appearance improved. Decontamination with lactic acid decreased mesophilic aerobic colony counts from 5.6 to 2.7 log10 CFU/cm2. After 14 d of storage the so-called “delayed” effect of lactic acid was still observed. At that time aerobic colony counts and Enterobacteriaceae counts of controls were 6.5 and 2.8 log10 CFU/cm2, while these counts of the lactic acid treated group were 4.0 and &lt;1.3, respectively. Results of the bacteriological examinations were substantiated by the histobacterioscopic findings. Centrifugation with lactic acid detached superficial cells from the stratified squamous epithelium. Decontamination of tongues by centrifugation with lactic acid before vacuum packaging will increase storage life and safeguard public health.

Studies on the manufacture of sweet cream starter butter: II. Effect of variation in proportion of starter added to cream

1960 ◽  
Vol 27 (1) ◽  
pp. 91-102 ◽  
Author(s):  
F. H. McDowall ◽  
J. A. Singleton ◽  
B. S. Le Heron
Keyword(s):  
Lactic Acid ◽  
Low Temperatures ◽  
Starter Culture ◽  
Skim Milk ◽  
Ph Values ◽  
Commercial Scale ◽  
Increase With Increase ◽  
Keeping Quality ◽  
Higher Temperature

SummaryProduction of diacetyl and acetoin by starters in cold skim-milk and cream was shown to increase with increase in the proportion of starter culture added, with some limitations at the higher rates of starter addition.With Streptococcus diacetilactis starter in skim-milk at 50°F the relation between proportion of starter added and production of diacetyl was linear up to addition at the 4% level, whereas at 43°F it was approximately linear up to the 10% level. At both 50 and 43°F the relation between the proportion of starter added and the production of acetoin was linear up to the 10% level.With Camb starter in skim-milk at both 50 and 43°F there were regular increases in production of diacetyl up to the 4% level of addition, but only minor changes thereafter with increase in the proportion of starter added up to 10%. At both temperatures the maximum production of acetoin was reached with the 7% rate of addition.Production of diacetyl and acetoin in skim-milk was greater at 50°F than at 43°F with both starters for all proportions up to 10%, and it was greater for Str. diacetilactis than for the mixed cultures.Except at the higher rates of addition of starter and at the higher temperature there were no concomitant increases in the acidity of the milk or lowering of the pH values. It appears that at low temperatures production of diacetyl by starters in sweet milk and cream proceeds independently of production of lactic acid.Similar results were obtained in a series of experimental buttermaking trials and some small commercial-scale trials, in which varying proportions of starter were added to creams after pasteurizing and before holding overnight for churning. With the cream-holding temperatures used, mainly 40–50°F, the pH values of the butters were not appreciably lowered by the starter additions to the cream. At all the rates of addition there were with Str. diacetilactis starter higher contents of diacetyl in the butter than with Camb starter. There was no indication of any relationship between the proportion of starter added and the keeping quality of the butter.

Chemical and Microbiological Quality of Raw Milk Produced by Smallholder Farmers in Zimbabwe

1996 ◽  
Vol 59 (9) ◽  
pp. 984-987 ◽  
Author(s):  
A. N. MUTUKUMIRA ◽  
S. B. FERESU ◽  
J. A. NARVHUS ◽  
R. K. ABRAHAMSEN
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Smallholder Farmers ◽  
Microbiological Quality ◽  
Titratable Acidity ◽  
Raw Milk ◽  
Chemical Characteristics ◽  
Yeasts And Molds ◽  
Microbiological Analyses

Chemical and microbiological analyses were carried out on 10 samples of raw milk collected over 6 months from the Nharira/Lancashire Milk Collection Center. The milk center is run by smallholder farmers. The purpose of the study was to evaluate the quality of the raw milk delivered to the milk collection center. The average chemical characteristics of the milk were (%): titratable acidity expressed as lactic acid, 0.21; total protein, 3.19; fat, 3.52; total solids, 11.76; and solids not fat, 8.25; the pH varied from 6.15 to 6.65. There were large variations in the microbiological composition of the raw milk with total aerobic counts ranging from 6.2 × 103 to 7.8 × 107 CFU/ml, coli forms from 3.2 × 102 to 2.3 × 105, and lactic acid bacteria from less than 1 × 103 to 2.9 × 106 CFU/ml. Yeasts and molds were less than 100 CFU/ml in 7 of the 10 samples analyzed.

Keeping quality and raw-milk grading: I. Dye tests as measures of the keeping quality of milk

1950 ◽  
Vol 17 (2) ◽  
pp. 159-191 ◽  
Author(s):  
A. T. R. Mattick ◽  
A. Rowlands ◽  
H. Barkworth ◽  
Zena Hosking ◽  
O. Kempthorne
Keyword(s):  
Raw Milk ◽  
Keeping Quality ◽  
Quality Of Milk

The experiments analysed in this series of papers were undertaken as the result of a discussion on methods of measuring the keeping quality of milk, at a Conference of Advisory Bacteriologists of the Ministry of Agriculture and Fisheries.Owing to the disturbance and difficulty following the outbreak of war and the dislocation of handling and distribution, a serious decline in the keeping quality of raw-milk supplies was threatened.

scholarly journals Evaluation of the Hygienic Quality of Raw Cow’s Milk in Oujda City Morocco

2017 ◽  
Vol 14 (2) ◽  
pp. 587-591
Author(s):  
K. Mchiouer ◽  
S. Bennani ◽  
N. Sh. El-Gendy ◽  
M. Meziane
Keyword(s):  
Staphylococcus Aureus ◽  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Fecal Coliform ◽  
Raw Milk ◽  
Total Coliform ◽  
Aerobic Bacteria ◽  
Milk Samples ◽  
Fecal Streptococci

ABSTRACT: The aim of this study is to determine the microbiological quality of raw cows’ milk of Oujda city. Raw milk samples are collected randomly between June 2014 and May 2015 from 20 Mahlaba (dairies) for microbiological evaluation. The samples are analyzed to determine total mesophilic aerobic bacteria (TMAB), total coliform, fecal coliform, staphylococcus aureus, fecal streptococci, proteolytic bacteria and lactic acid bacteria. The results of bacterial count showed that there is a variation between all the milk samples and a period effect is also observed. The mean counts of total mesophilic aerobic bacteria from all sale points are between 1.76×106 and 40.17×106 CFU/ml. Milk samples reveled counts total coliform and fecal coliform ranging from 0.58×105 to 11.10×105 CFU/ml and from 0.60×103 to 14.64×103 CFU/ml, respectively. Staphylococcus aureus are also detected in all samples with counts ranging from 0.35 ×103 to 3.08×103 CFU/ml. Fecal streptococci are found in all milk samples, at counts ranging from 0.16 ×102 to 2.18 ×102 CFU/ml. And finally, proteolytic and lactic acid bacteria are between 0.3×103 and 2.86×103 CFU/ml and 2.37×106 and 24.14 ×106 CFU/ml respectively. These results indicate a lack of compliance with good manufacturing practice at milking, collection and transportation of raw milk.

Effect of Pullulan on Physicochemical, Microbiological, and Sensory Quality of Yogurts

2019 ◽  
Vol 20 (6) ◽  
pp. 489-496 ◽  
Author(s):  
Anna Chlebowska-Śmigiel ◽  
Katarzyna Kycia ◽  
Katarzyna Neffe-Skocińska ◽  
Marek Kieliszek ◽  
Małgorzata Gniewosz ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Sensory Quality ◽  
Culture Medium ◽  
Titratable Acidity ◽  
Refrigerated Storage ◽  
Ph Change ◽  
Fermentation Capacity ◽  
Dietetic Food

Background: Pullulan can partially or completely replace starch or fat, thanks to which it can be used for the production of dietetic food. It allows you to maintain the desired consistency, and increases the viscosity of the product. Objective: Therefore, an attempt was made to produce yogurts with pullulan addition and determine the effect of its presence on the number of LAB, pH change, titratable acidity, and sensory quality of yogurts during storage at 4°C for 28 days. Method: The effect of addition of 0; 1.0 and 2.0 % w/v pullulan as a yogurt ingredient on the changes in pH, acidity, LAB number, and sensory quality of yogurt during storage at 4°C for 28 days was examined. Results: Pullulan did not affect yogurt pH, but the addition of 2.0 % w/v pullulan increased the acidity of yogurt as compared to that of the control yogurt. A statistically significantly higher total number of Lactobacillus, by approximately 1 logarithmic cycle, was found in yogurts with pullulan than in the control yogurt on the 28th day of storage. The yogurt with 1.0% w/v pullulan addition showed better sensory characteristics than that with 2.0% pullulan w/v addition. Conclusion: The conducted research proved that the presence of pullulan in the culture medium stimulates the growth of selected lactic acid bacteria and influences their fermentation capacity. The use of 1.0 % w/v pullulan during the production of yogurts allowed to obtain a sensorically acceptable product, it had a protective effect on the number of lactic acid bacteria during 28 days of refrigerated storage of yogurt.

462. The keeping quality of composite milk

1952 ◽  
Vol 19 (1) ◽  
pp. 63-71 ◽  
Author(s):  
J. Babad ◽  
A. Shenhav-Hetman
Keyword(s):  
Milk Powder ◽  
Skim Milk ◽  
Raw Milk ◽  
Skim Milk Powder ◽  
Keeping Quality ◽  
Better Than

The keeping quality of various mixtures, made up of raw milk and skim milk-powder in varying proportions, has been studied. It has been found that the keeping quality of unpasteurized samples containing milk powder was slightly better than that of raw milk. The keeping quality of the pasteurized mixtures was satisfactory during the time of storage for 40 hr. at 23 and 18° C. and for 60 hr. at 10° C.

Effect of carbon dioxide on improving the keeping quality of raw milk

1986 ◽  
Vol 39 (2) ◽  
pp. 62-64 ◽  
Author(s):  
M. A. RASHED ◽  
N. M. MEHANNA ◽  
A. S. MEHANNA
Keyword(s):  
Carbon Dioxide ◽  
Raw Milk ◽  
Keeping Quality
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