Molecular details of the formation of soluble aggregates during ultrafiltration or microfiltration combined with diafiltration of skim milk

2022 ◽  
Vol 124 ◽  
pp. 107244
Author(s):  
Özgenur Coşkun ◽  
Lars Wiking ◽  
Saeed Rahimi Yazdi ◽  
Milena Corredig
Keyword(s):  
2006 ◽  
Vol 73 (1) ◽  
pp. 79-86 ◽  
Author(s):  
Marie Renan ◽  
Omar Mekmene ◽  
Marie-Hélène Famelart ◽  
Fanny Guyomarc'h ◽  
Véronique Arnoult-Delest ◽  
...  

The pH-dependent behaviour of soluble protein aggregates produced by the pre-heating of reconstituted skim milk at 90 °C for 10 min was studied, in order to understand the role of these aggregates in acid gelation of heated milk. The following milk samples were prepared: (1) control (unheated reconstituted milk, pH 6·5); (2) milk heat-treated at pH 6·5 (mHtd6·5) and (3) milk heat-treated at pH 7·2 (mHtd7·2). They were centrifuged and the supernatants (SPNT 1) pH-adjusted to yield a series of pH values ranging from 6·5 or 7·2 to 4·6 using HCl at 20 °C or GDL at 20 and 38 °C. pH-Adjusted SPNTs 1 were re-centrifuged. The resulting supernatants (SPNTs 2) were analysed by OD (at 600 and 280 nm) and SDS-PAGE in order to characterise proteins still soluble as a function of pH. Particle size in SPNTs 1 was analysed by Steric Exclusion Chromatography. The OD600 nm revealed that during acidification soluble casein in both control and heat-treated samples exhibits variations in its optical properties or size as previously shown with micellar casein. In heat-treated samples, soluble casein and heat-induced covalent soluble aggregates precipitate at the same pH value. A progressive acidification of the soluble phase did not separate them. Increasing the temperature of acidification from 20 to 38 °C resulted in an increase in the precipitation pH of the proteins. However choice of acidifier did not have a significant effect on OD profiles. The soluble covalent aggregates from mHtd7·2 were smaller, more numerous, and had a higher content of κ-casein than mHtd6·5. Both types of aggregates began to precipitate at the same pH value but precipitation occurred over a narrower pH-range for soluble aggregates prepared from mHtd7·2. This may explain the higher gelation pH of mHtd7·2 compared with mHtd6·5.


Author(s):  
Ghanyia J. Shanyoor ◽  
Fatima R. Abdul ◽  
Nehad A. Taher ◽  
Ihsan A. Raheem

About (20) Pseudomonas rogenosa isolate were experienced for their ability of protease production by calculating the diameter of lysis area after developing on skim milk agar medium (qualitatively ) and the results exhibited that only isolate no (5), was higher isolate for protease making of (26mm) of lysis area. Then, the protein concentration also identified by Bradford method and it was found of 0.16 mg/ ml , then purification was done by using an ion- exchange chromatography with DEAE sephadex G- 100 column and the results showed the presence of 1 peak of enzyme with 50 Kd of molecular weight 2 peaks of other proteins . we tried to investigate the invitro Cytotoxic effect of purified enzyme against two human cancer lines, HeP2 (Human larynx epidermed carcinoma ) , RD ( Rabdo- Sarcoma ) , and one normal cell line Ref ( Rat embryonic fibroblast ) . The cancer and normal cells were treated with different concentrations of protease enzyme ranging from ( 0.05, 0.1, 0.2, 0.4,0.8and 0.16 mg/ml) then incubated for additional 48h at 37C0 and the results showed highest toxicity ( 80.28%) of protease enzyme on RD , moderate cytotoxicity (45.52%) on Hep andslight toxicity ( 37.12% ) on normal cell line (Ref) in a concentration (0.8mg/ml).


2018 ◽  
pp. 14-15
Author(s):  
Anisimov G.S. ◽  
◽  
Evdokimov I.A. ◽  
Ryabtseva S.A. ◽  
Donskih A.N. ◽  
...  

2019 ◽  
pp. 48-50 ◽  
Author(s):  
O.V. Salova ◽  
◽  
S.A. Ryabtseva ◽  
Y.A. Tabakova ◽  
G.S. Anisimov ◽  
...  
Keyword(s):  

2017 ◽  
Vol 9 (1) ◽  
pp. 16
Author(s):  
Amanda Kania Diandini

The safe ice cream which is consumed by Diabetes Mellitus sufferers is made by subtituting skim milk, cream and sugar with kefir, pure pumpkin, cornstarch, vegetable oil, and artificial sweetener special gor Diabetes Mellitus. Kefir is known can decrease (blood sugar) because of its bioactive content. The aim of this research is knowing predilection level test to ice cream pumpkin kefir. This research is conducted with experimental method. The data analysis includes predilection test, nutrient value analysis, and price analysis. Ice cream pumpkin kefir that is liked most are from texture side, the cheapest price, and also the highest fiber content exists in balance 578 with the ratio of kefir and pumpkin 50%:50%. Ice cream pumpkin kefir that is liked most from colour side exists in balance 236 with the ratio of kefir and pure pumpkin 70%:30%. Ice cream pumpkin kefir that is liked most from taste side and aroma exists in balance 522 with the ratio between kefir and pure pumpkin 80%:20%.


2019 ◽  
Vol 6 (03) ◽  
Author(s):  
PK SUNDARAM ◽  
BIKASH SARKAR ◽  
UJJWAL KUMAR ◽  
AP ANURAG ◽  
DK RAGHAV ◽  
...  

About (20) Pseudomonas rogenosa isolate were experienced for their ability of protease production by calculating the diameter of lysis area after developing on skim milk agar medium (qualitatively ) andamp; the results exhibited that only isolate no (5), was higher isolate for protease making of (26mm) of lysis area. Then, the protein concentration also identified by Bradford method andamp; it was found of 0.16 mg/ ml , then purification was done by using an ion- exchange chromatography with DEAE sephadex G- 100 column andamp; the results showed the presence of 1 peak of enzyme with 50 Kd of molecular weight 2 peaks of other proteins . we tried to investigate the invitro Cytotoxic effect of purified enzyme against two human cancer lines, HeP2 (Human larynx epidermed carcinoma ) , RD ( Rabdo- Sarcoma ) , andamp; one normal cell line Ref ( Rat embryonic fibroblast ). The cancer andamp; normal cells were treated with different concentrations of protease enzyme ranging from ( 0.05, 0.1, 0.2, 0.4,0.8andamp; 0.16 mg/ml) then incubated for additional 48h at 37C 0 andamp; the results showed highest toxicity ( 80.28%) of protease enzyme on RD , moderate cytotoxicity (45.52%) on Hep andamp;slight toxicity ( 37.12% )on normal cell line (Ref) in a concentration (0.8mg/ml).


1984 ◽  
Vol 67 (3) ◽  
pp. 637-640 ◽  
Author(s):  
David O Biltcliffe ◽  
Dick H Kleyn ◽  
J Richard Trout ◽  
◽  
D Azzara ◽  
...  

Abstract Collaborators in 8 dairy and food industry laboratories performed one lactose determination on each of 8 unknown samples of milk, lowfat milk, or skim milk, as 3 pairs of blind duplicates. Two known samples were provided to gain experience prior to analysis of the unknown samples. All of the above samples were also analyzed for lactose content by the official AOAC gravimetric method (16.507) by a commercial laboratory. From the overall mean of results on all samples, determinations by the enzymatic method averaged 0.49% lower than by the AOAC method. This difference was significant by the t-test (P = 0.05), which indicated a lack of agreement between the compared methods in determining lactose content. Standard deviations were similar for the 3 sets of blind duplicates which ranged between 3.67 and 4.55% lactose content. F-values revealed that variations between means obtained by laboratories differed significantly as compared with variations within laboratory means. The method has been adopted official first action.


1982 ◽  
Vol 45 (6) ◽  
pp. 561-565 ◽  
Author(s):  
R. T. MARSHALL ◽  
Y. H. LEE ◽  
B. L. O'BRIEN ◽  
W. A. MOATS

Samples of skim milk and nonfat dry milk (NDM) made from it were collected, paired and tested for pyruvate concentration, [P], and Direct Microscopic count (DMC). The skim milk was tested for Standard Plate Count (SPC) and Psychrotrophic Plate Count (PPC). The geometric average DMC of skim milk was more than three times higher than that of the paired NDM samples. However, [P] of NDM was not significantly different from that of the skim milk. Although [P] of skim milk was poorly correlated with SPC and PPC, r = .31 and .26, respectively, it was relatively well correlated with DMC, r = .64. Data were widely dispersed around the regression line when [P] was ≤ 4.0 mg/L. However, [P] increased rapidly when DMCs were > 106/ml. A limit of 10 mg/L of [P] in NDM reconstituted 1:9 was chosen to represent the current U.S. Department of Agriculture Standard for DMC in NDM. This limit failed to classify about 10% of the samples correctly, assuming that each geometric mean DMC was correct. However, the probability that samples meeting the DMC standard would be rejected by the pyruvate test was quite low and the probability was moderate that samples which would be acceptable by the pyruvate test would be rejected by the DMC. For the latter, 28% of the samples having DMCs of ≥ 107/ml contained < 10 mg/L of pyruvate. No sample having ≥ 10 mg/L of pyruvate had a DMC of ≤ 107/ml. Pyruvate concentration in NDM did not change during storage at 5 or 32°C for 90 days.


1989 ◽  
Vol 52 (12) ◽  
pp. 852-855 ◽  
Author(s):  
SEHAM A. FARRAG ◽  
ELMER H. MARTH

Autoclaved samples of skim milk were inoculated with Listeria monocytogenes (strain Scott A, California or V7), Pseudomonas fluorescens (strain P26 or B52), or a combination of L. monocytogenes plus P. fluorescens, and incubated at 7 or 13°C for 8 weeks. McBride Listeria Agar was used to determine populations of L. monocytogenes (at 0, 7, 14, 28, 42, or 56 d), and Pseudomonas isolation agar to enumerate P. fluorescens. Growth of L. monocytogenes was somewhat enhanced after 7 d of incubation at 7 but not at 13°C in the presence of pseudomonads. However, after 14 d and until the end of the incubation period (56 d), slight inactivation of L. monocytogenes in the presence of P. fluorescens was observed. L. monocytogenes did not affect growth or survival of P. fluorescens; also, no marked changes in pH of the milk were caused either by L. monocytogenes alone or by L. monocytogenes plus P. fluorescens.


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