Water mobility in acidified milk drinks studied by low-field 1H NMR

Effects of addition of phenolic compounds on the acid gelation of milk

“…During acidification of the skim milk two mobile water phases T 21 (0.1 mse100 ms) and T 22 (100 mse1000 ms) were detectable by means of T 2 relaxation times (Fig. 5), in agreement with Mok, Qi, Chen, and Ruan (2008) and Salomonsen et al (2007). In these studies the T 21 phase appeared immediately after GDL addition; however in the present study T 21 appeared after w1 h of gelation.…”

“…5). Previous studies have suggested that a broader distribution of T 2 corresponds to more inhomogeneous samples (Salomonsen et al, 2007). This was in agreement with the rheological properties of the gel containing 1% gallic acid, as the final G 0 at 30 C was very low (56 AE 14 Pa) indicating manufacture of a very weak gel.…”

“…Similarly, Mok et al (2008) found an increase in T 2 times as yogurt gel network formed and Hinrichs, Bulca, and Kulozik (2007) reported an increase in the relaxation time of the mobile phase during the acid coagulation of casein solutions due to the evolving microstructure of these gels. The T 22 times obtained for the control gel were similar to previous studies although the milk was not acidified in the same way; milks acidified with HCl were reported to have a T 2 value of w250 ms (Roefs, van As, & van Vilet, 1989), a lower T 2 value of w194 ms was reported for milk drinks acidified with bacteria (Salomonsen et al, 2007) and a T 2 value of w250 ms was found for set yogurts (Mok et al, 2008). The addition of tannic acid (1%) to the skim milk before GDL addition resulted in an immediate decrease in the T 22 time from 137.2 ms in reconstituted skim milk powder to 62.9 ms, indicating that the addition of tannic acid immediately caused the water within the skim milk to become less mobile.…”

“…More recently, the water mobility in acidified milk drinks has been studied using nuclear magnetic resonance (NMR) and it has been used to detect textural problems such as whey separation (Salomonsen, Sejersen, Viereck, Ipsen, & Engelsen, 2007). The rheological properties and water mobility of these gels may be modified by fortification with either dairy or non-dairy ingredients, such as starch (Oh, Anema, Wong, Pinder, & Hemar, 2007) or pectin (Matia-Merino & Singh, 2007;Salomonsen et al, 2007). Phenolic compounds or extracts rich in phenolic compounds may be ideal ingredients to add to milk gels as they could improve the nutritional value and may also enhance the rheological properties, but to date there has been little work published on the addition of phenolic compounds to acidified milk gels.…”

A novel, sensitive and non‐destructive method for quantitative determination of lipid in live Eriocheir sinensis using low‐field 1H Nuclear magnetic resonance

“…Low‐field 1 H Nuclear magnetic resonance (LF‐ 1 H NMR) technique is a rapid, non‐destructive, highly reproducible, and sensitive technique (Hazlett et al., 1999; Seton, Hutchison, & Bussell, 1997), and has successfully been applied in quality control of food products such as porcine muscle (Qin, Xu, Zhou, & Wang, 2015; Shao, Deng, Jia, et al., 2016; Shao, Deng, Song, et al., 2016), pork (Shao, Deng, Jia, et al., 2016; Shao, Deng, Song, et al., 2016), salmon (da Silva Carneiro et al., 2016), crude lipid (Barbosa, Sad, Morgan, Figueiras, & Castro, 2016; Jia et al., 2016), egg (Zhao et al., 2016), milk (Salomonsen, Sejersen, Viereck, Ipsen, & Engelsen, 2007), honey (Ribeiro et al., 2014), and cod (Gudjónsdóttir, Arason, & Rustad, 2011). The LF‐ 1 H NMR technique is often employed to investigate the water mobility and/or lipid content of foods because it can measure water or lipid proton relaxation.…”