The influence of temperature and solid matter content on the viscosity of whey protein concentrates and skim milk powder before and after tribomechanical treatment

2005 ◽  
Vol 66 (4) ◽  
pp. 433-438 ◽  
Author(s):  
Zoran Herceg ◽  
Vesna Lelas
2005 ◽  
Vol 85 (4-5) ◽  
pp. 315-323 ◽  
Author(s):  
François Morgan ◽  
Corinne Appolonia Nouzille ◽  
Robert Baechler ◽  
Gilles Vuataz ◽  
Alois Raemy

2018 ◽  
Vol 39 (2) ◽  
pp. 631
Author(s):  
Janislene Mach Trentin ◽  
Luiz Augusto Machado Centeno ◽  
Taison De Souza Balestrin ◽  
Thainá Minela ◽  
Guilherme Machado Zanatta ◽  
...  

The composition of semen diluents can modify its viability during cooling. The buffering effects of HEPES and sodium bicarbonate were evaluated considering the pH and sperm viability. The semen of seven adult Brazilian ponies was evaluated before and after cooling at 5oC for 24 h and 48 h. A non-buffered skim milk powder extender (C) and the same extender buffered with sodium bicarbonate (SB) and HEPES (H) were used. After dilution, semen (three ejaculates/pony) was centrifuged and the seminal plasma discarded. Sperm was then diluted with SB, H or C and its concentration adjusted to 50 x 106 sptz/mL. Progressive motility evaluated after dilution showed similar results with all extenders (71.42% (SB), 74.28% (H), and 74.52% (C)). Sperm motility was evaluated 24 h and 48 h after cooling for SB (44.76% and 25.23%), H (51.42% and 38.09%) and C (54.05% and 41.66%, respectively). Plasma membrane integrity was similar after exposure to the three extenders (62.71% (SB), 68.76% (H), and 69.23% (C)). Mitochondrial activity was higher in SB immediately after dilution (SB= 1.05nm, H= 0.81nm, C= 0.79nm), and after 24 h (0.83nm (SB), 0.73nm (H) and 0.64nm (C)). After 48 h, the mitochondrial activity decreased to 0.72nm (SB), 0.69nm (H), and 0.63nm (C) (P > 0.05). The pH, osmolarity and pH after 48 h of cooling of the diluted semen were higher in SB (8; 382; 7.9), intermediate in H (7.5; 362; 7.32) and lower in C (7.16; 350; 7.07). Lipid peroxidation and its induction were similar in all groups. Data were analyzed by analysis of variance (ANOVA), and Duncan’s test was used to evaluate the significant differences (P < 0.05). Sodium bicarbonate reduced the progressive motility and increased the semen pH. The extender C was considered more appropriate for immediate use in artificial insemination. The non-buffered and HEPES-buffered extenders were considered appropriate for the cooling of equine semen for 48 h at 5°C.


1976 ◽  
Vol 56 (2) ◽  
pp. 335-338
Author(s):  
D. B. EMMONS ◽  
E. E. LISTER ◽  
D. L. CAMPBELL

Reconstituted commercial skim milk powder samples which produced a firm (> 30 g) rennet curd had high levels (> 4 mg N/g) of undenatured whey protein nitrogen (WPN) as measured by the modified Harland–Ashworth test. However, similar samples which also had high levels of WPN (> 6 mg N/g) had low curd firmness or failed to coagulate. Of 24 commercial samples of milk replacers, 2 formed a soft curd; the rest did not coagulate. Five had high levels of WPN (> 6 mg N/g); one sample contained 17.8 mg N/g, well above normal levels of skim milk powder. Plant proteins may have caused high WPN values and interfered with the Harland–Ashworth test. It was concluded that WPN is neither an acceptable index of rennet coagulability of milk replacers, nor a reliable index for selecting commercially produced skim milk powders with good rennet coagulability.


1984 ◽  
Vol 51 (4) ◽  
pp. 623-628 ◽  
Author(s):  
Donald Stead

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.


1992 ◽  
Vol 59 (2) ◽  
pp. 177-185 ◽  
Author(s):  
Catharina H. McCrae ◽  
D. Donald Muir

SummaryTwo types of lecithin, namely egg and soya lecithin, were investigated as potential stabilizers of recombined milk. They were incorporated into recombined milk both before and after homogenization (20·7 MPa; 60 °C). Their presence at homogenization changed neither mineral equilibria nor homogenization efficiency. However, heat stability varied significantly irrespective of batch of low-heat skim milk powder used in recombined milk. The variation in heat stability depended on type of lecithin. Soya lecithin proved to be a very effective stabilizer. It improved heat stability over a wide pH range (6·3–7·1) and the effect occurred even when the lecithin was added after homogenization. In contrast, egg lecithin destabilized the system to heat at pH < 6·7 by converting a Type A into a Type B heat coagulation time-pH profile if it was incorporated before homogenization; after homogenization it had no effect. The effects of both egg and soya lecithin on the heat stability of recombined milk strongly suggest that interactions occur between phospholipids and milk protein.


2018 ◽  
Vol 38 (2) ◽  
pp. 178
Author(s):  
Mohamad Djali ◽  
Syamsul Huda ◽  
Lovita Andriani

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.


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