scholarly journals Effect of heat treatment at alkaline pH on the rennet coagulation properties of skim milk

2005 ◽  
Vol 85 (6) ◽  
pp. 515-526 ◽  
Author(s):  
Olivia Ménard ◽  
Bénédicte Camier ◽  
Fanny Guyomarc’h
Keyword(s):  
Heat Treatment ◽  
Skim Milk ◽  
Alkaline Ph ◽  
Rennet Coagulation

scholarly journals Changes in the acid gelation of skim milk as affected by heat-treatment and alkaline pH conditions

2007 ◽  
Vol 87 (2) ◽  
pp. 119-137 ◽  
Author(s):  
Fanny Guyomarc’h ◽  
Orlane Mahieux ◽  
Marie Renan ◽  
Marc Chatriot ◽  
Valérie Gamerre ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Skim Milk ◽  
Alkaline Ph ◽  
Ph Conditions ◽  
Acid Gelation

Rheological properties of milk gels formed by a combination of rennet and glucono-δ-lactone

2000 ◽  
Vol 67 (3) ◽  
pp. 415-427 ◽  
Author(s):  
JOHN A. LUCEY ◽  
MICHELLE TAMEHANA ◽  
HARJINDER SINGH ◽  
PETER A. MUNRO
Keyword(s):  
Heat Treatment ◽  
Rheological Properties ◽  
Large Scale ◽  
Whey Proteins ◽  
Skim Milk ◽  
Rheological Behaviour ◽  
Intermolecular Forces ◽  
Heated Milk ◽  
Rennet Coagulation ◽  
Tan Δ

The effects of heat treatment of milk, and a range of rennet and glucono-δ-lactone (GDL) concentrations on the rheological properties, at small and large deformation, of milk gels were investigated. Gels were made from reconstituted skim milk at 30 °C, with two levels each of rennet and GDL. Together with controls this gave a total of sixteen gelation conditions, eight for unheated and eight for heated milk. Acid gels made from unheated milks had low storage moduli (G′) of < 20 Pa. Heating milks at 80 °C for 30 min resulted in a large increase in the G′ value of acid gels. Rennet-induced gels made from unheated milk had G′ values in the range ∼ 80–190 Pa. However, heat treatment severely impaired rennet coagulation: no gel was formed at low rennet levels and only a very weak gel was formed at high levels. In gels made with a combination of rennet and GDL unusual rheological behaviour was observed. After gelation, G′ initially increased rapidly but then remained steady or even decreased, and at long ageing times G′ values increased moderately or remained low. The loss tangent (tan δ) of acid gels made from heated milk increased after gelation to attain a maximum at pH ∼ 5·1 but no maximum was observed in gels made from unheated milk. Gels made by a combination of rennet and GDL also exhibited a maximum in tan δ, indicating increased relaxation behaviour of the protein–protein bonds. We suggest that this maximum in tan δ was caused by a loosening of the intermolecular forces in casein particles caused by solubilization of colloidal calcium phosphate. We also suggest that in combination gels made from unheated milk a low value for the fracture stress and a high tan δ during gelation indicated an increased susceptibility of the network to excessive large scale rearrangements. In contrast, combination gels made from heated milk formed firmer gels crosslinked by denatured whey proteins and underwent fewer large scale rearrangements.

Rennet coagulation of heated milk: influence of pH adjustment before or after heating

1988 ◽  
Vol 55 (2) ◽  
pp. 205-215 ◽  
Author(s):  
Harjinder Singh ◽  
Samweul I. Shalabi ◽  
Patrick F. Fox ◽  
Albert Flynn ◽  
Anne Barry
Keyword(s):  
Heat Treatment ◽  
Adverse Effect ◽  
Adverse Effects ◽  
Skim Milk ◽  
Ph Adjustment ◽  
Milk Samples ◽  
Heated Milk ◽  
Rennet Coagulation ◽  
Low Concentrations ◽  
Influence Of Ph

SummaryThe rennet coagulation times of infant milk formulae or fresh skim milk (milk) samples heated at temperatures in the range 70–140 °C for 1–10 min decreased on acidification, usually to pH < 6·0. Heated milk samples acidified to pH 5·5 and reneutralized to pH 6·6 retained good rennet coagulability. Acidification of such milk samples before heating also reduced the adverse effect of severe heat treatment (95 °C for 1 min) on rennet coagulation. Addition of low concentrations of CaCl2 to heated milks offset the adverse effects of heating. Acidification of heated milks increased the [Ca2+], and reneutralization of acidified milk only partly restored the [Ca2+], i.e. acidified/reneutralized milk had a higher [Ca2+] than normal milk, suggesting this as the mechanism via which acidification/neutralization improves the rennet coagulability of heated milk. Approximately 50% of the whey protein can be incorporated into rennet gels in heated milks while retaining good coagulability and curd tension; this may be a useful technique for increasing cheese yield.

scholarly journals Rennet coagulation of skim milk and curd drainage: effect of pH, casein concentration, ionic strength and heat treatment

2000 ◽  
Vol 80 (4) ◽  
pp. 397-415 ◽  
Author(s):  
Célina Daviau ◽  
Marie-Hélène Famelart ◽  
Alice Pierre ◽  
Henri Goudédranche ◽  
Jean-Louis Maubois
Keyword(s):  
Heat Treatment ◽  
Ionic Strength ◽  
Skim Milk ◽  
Effect Of Ph ◽  
Rennet Coagulation ◽  
Drainage Effect

Assessment of the rennet coagulation of skim milk: A comparison of methods

2007 ◽  
Vol 17 (10) ◽  
pp. 1151-1160 ◽  
Author(s):  
A.H. Klandar ◽  
A. Lagaude ◽  
D. Chevalier-Lucia
Keyword(s):  
Skim Milk ◽  
Comparison Of Methods ◽  
Rennet Coagulation

Distribution and Resistance to Pasteurization of Aflatoxin M1 in Naturally Contaminated Whole Milk, Cream and Skim Milk

1983 ◽  
Vol 46 (6) ◽  
pp. 530-532 ◽  
Author(s):  
DANA W. WISEMAN ◽  
RHONÁS. APPLEBAUM ◽  
ROBERT E. BRACKETT ◽  
ELMER H. MARTH
Keyword(s):  
Heat Treatment ◽  
Skim Milk ◽  
Aflatoxin M1 ◽  
Whole Milk

Milk, naturally contaminated with aflatoxin M1 (AFM1) was separated with a hand-operated separator. Distribution of AFM1 paralleled the partitioning of whole milk into cream and skim milk. Most of the whole milk was recovered as skim milk, which also contained most of the AFM1. Cream accounted for 5–15% of the amount of whole milk and had 2–14% of AFM1 that originally occurred in whole milk. Cream and skim milk were pasteurized at 64°C for 30 min, AFM1 was stable in both products given this heat treatment.

Heat Resistance of Escherichia coli in Cow and Buffalo Milk

1980 ◽  
Vol 43 (5) ◽  
pp. 376-380 ◽  
Author(s):  
R. S. SINGH ◽  
B. RANGANATHAN
Keyword(s):  
Escherichia Coli ◽  
Heat Treatment ◽  
Heat Resistance ◽  
Skim Milk ◽  
Buffalo Milk ◽  
Time Interval ◽  
E Coli ◽  
Heat Resistant ◽  
Whole Milk

Three Escherichia coli cultures (0111:B4, 0127:B8 and NP) were selected to study their heat-resistant characteristics when in cow skim, cow whole and buffalo whole milk. The temperatures of heat-treatment included in this study were 50, 55, 60 and 63 C. The time interval during heat-treatment was 10 min at 50 and 55 C and 5 min at 60 and 63 C. Marked differences in heat-resistance were observed in the three E. coli cultures. The z-values obtained for strain 0111:B4 were 8.3, 9.0 and 10.2 when tested in cow skim milk, cow whole milk and buffalo milk, respectively. The z-values for 0127:B8 and NP were 17.5, 18.0 and 19.2 and 18.8, 19.0 and 20.3, respectively, for the three types of milk.

The influence of milk composition on pH and calcium activity measured in situ during heat treatment of reconstituted skim milk

2010 ◽  
Vol 77 (3) ◽  
pp. 257-264 ◽  
Author(s):  
Jayani Chandrapala ◽  
Ian McKinnon ◽  
Mary Ann Augustin ◽  
Punsandani Udabage
Keyword(s):  
Heat Treatment ◽  
High Temperatures ◽  
Skim Milk ◽  
Milk Composition ◽  
Complexing Agents ◽  
Calcium Activity ◽  
Initial Ph ◽  
Ph Decrease ◽  
Milk Solids

The pH and calcium activity of reconstituted skim milk solutions (9–21% w/w milk solids non-fat) on heating and after cooling were studied as a function of milk pH prior to heating (pH 6·2–7·2 at 25°C) and added calcium complexing agents (phosphate or EDTA). The pH decreased as the temperature was raised from 25 to 90°C and the magnitude of the pH decrease was greater with increase in initial pH at 25°C before heating or milk concentration. The pH decrease on heating from 25 to 90°C in skim milk solutions with added calcium complexing agents was lower than that of milk without the addition of these salts. The calcium activity decreased on heating from 25 to 60°C. The magnitude of the change decreased with increase in initial pH at 25°C before heating and milk concentration. The decrease in calcium activity on heating from 25 to 60°C for skim milk solutions with added calcium complexing agents was lower than that of milk solutions without the addition of calcium complexing agents. The changes in pH and calcium activity on heating milk were largely reversible after cooling the milk. The results suggested that the pH and calcium activity at high temperatures are a function of the milk composition. Knowledge of the initial pH prior to heating alone is not sufficient for predicting the changes that occur during heating.

Sign in / Sign up

Export Citation Format

Share Document