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The effect of nanosized bamboo dietary fiber (NBDF) on whey syneresis in yogurt during shelf storage was studied. The milk wettability of micro- and nano-modified NBDF with different particle sizes was analyzed. The inhibitory mechanism of the modified NBDF exhibiting the best milk wettability on whey syneresis during the shelf storage of yogurt was investigated. The results showed that the morphology of NBDF changed from blocky to filamentous after sequential ultrasound, pressurized heating and enzymatic hydrolysis. The microfibrils were fractured after high-energy mechanical ball milling, forming nanoclusters. The milk wettability of modified NBDF initially increased and then decreased with the decrease in particle size. The microfibrils with a particle size of 10–30 μm had the strongest milk wettability. Addition of the microfibrils at a mass concentration of 9 g/L improved the oscillation stability of set yogurt. After 28 days of shelf storage, the whey separation rate was 5.84%, which was only 57.87% of that of the control group. This may be related to the fact that the microfibrils effectively increased the proportion of bound water in yogurt (by 41.4%), improved the casein network structure, and increased the coatability, contributing to the formation of tiny and uniform whey pore channels in yogurt.

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• Linoleic acid inhibiting whey syneresis in the fermentation of set yogurt. • LA interacts with CS, β -Lg and BSA and promotes cross-linking of milk proteins. • The set yogurt fortified with CLA possesses stable physicochemical characteristics. The study aimed to investigate the impact of fermentation conditions on c 9, t 11-conjugated linoleic acid (CLA) synthesis by Lactobacillus casei , as well as its effects on whey syneresis, water holding capacity (WHC), and texture characteristics of set yogurt. The amount of whey syneresis decreased about 30% with the adding of 0.1% linoleic acid (LA). The interaction between LA and casein (CS), β -lactoglobulin (β -Lg) and bovine serum albumin (BSA) was observed by UV–Vis absorption spectroscopy, 3D fluorescence spectroscopy and CD spectroscopy. It found that LA changed the microenvironment and polarity around amino acids, as well as the conformation of the three milk proteins. Scanning electron microscope (SEM) analysis revealed that the addition of LA resulted in a more uniform and compact microstructure of the set yogurt. It indicates that LA can promote the crosslink of milk proteins, which may be the reason for the reduction of whey syneresis in set yogurt. [ABSTRACT FROM AUTHOR]

Abstract: Milk from 94 Ethiopian goats (four breeds) was assessed for casein level, micellar size, coagulation properties and whey syneresis to evaluate cheese-making potential. Casein content (g/kg) ranged from 6.84 to 8.94 (αs1); 4.16–4.98 (αs2); 12.51–15.37 (β) and 6.89–8.93 (κ). Arsi-Bale goats had the highest αs1-casein (8.94g/kg) followed by the Somali goats (7.90g/kg); and were higher than Boer (7.05g/kg) and Cross (6.84g/kg) (P <0.001). Milk from Arsi-Bale and Somali goats had significantly (P <0.05) smaller micelles; 207.47 and 209.29nm respectively than Boer (230.30nm) and Cross (228.71nm). Significantly stronger gels (P <0.05) were obtained from milk samples with higher αs1-CN level and smaller micelles (Arsi-Bale 37.99mm and Somali 36.19mm) than samples with lower αs1-CN level and larger micelles (Boer 31.13mm and Cross 33.51mm). Syneresis was significantly higher (P <0.001) in milk with good coagulation properties. Curd firmness was negatively correlated with coagulation rate (R, −0.832) and micellar size (R, −0.647). Milk from Arsi-Bale and Somali goats had significantly higher αs1-CN level, smaller micelle and better cheese making property than the cross and Boer goats. This study shows that there exists high potential among indigenous goats for cheese production. [Copyright &y& Elsevier]

The quality of set mango yoghurt prepared by varying total milk solids ( TMS) level in mango yoghurt mix, by adding 5× ultrafiltered cow skim milk retentate and cow milk cream, was investigated. The water-holding capacity ( WHC) and values of textural attributes of mango yoghurt increased, whereas body and texture and overall acceptability scores decreased significantly ( P < 0.05) with increasing TMS level. The optimised product (10.2% TMS level) was compared with conventional mango yoghurt. Acetaldehyde concentration, WHC, values of textural attributes, body and texture, overall acceptability scores and pH were significantly ( P < 0.05) higher in optimised compared with conventional mango yoghurt. [ABSTRACT FROM AUTHOR]

This paper presents research on the effect of enzymatic cross-linking of milk proteins on the properties of yoghurt. Whole milk was incubated with transglutaminase (TG) prior to fermentation (2 h, 40°C, E/S ratio 1/2000). Enzyme action was stopped by heating (1 min, 80°C). Skim-milk was treated by simultaneous use of TG and thermophilic yoghurt starter culture without inactivation of the enzyme. A TG treatment of milk prior to fermentation led to prolonged fermentation, while the concomitant use of TG and culture had no influence on fermentation time. Post acidification of yoghurt during storage was lower for products from enzyme-treated milk. This applies both for products cross-linked prior to fermentation with enzyme inactivation, and for simultaneous use of culture and TG without inactivation of the enzyme. Scanning electron microscopic studies revealed that a TG treatment of milk led to reduced mesh sizes of the protein network, and a more regular distribution of the proteins in the yoghurt gel. As a result, yoghurt products from enzyme-treated milk showed increased gel strength and less syneresis, especially when the enzyme was not inactivated. Sensory studies revealed that odour and consistency properties of products from TG-treated milk were assessed as less ‘yoghurt specific’. On the other hand, products from enzyme-treated milk were described as being more creamy, indicating that a TG treatment may simulate fat in fermented milk products. [ABSTRACT FROM AUTHOR]