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# Investigate the use of three-different models for predicting the effect of time/temperature treatments on the formation of lactulose

The formation of lactulose from lactose has been described in the article on the UHT-processing of milk. Lactulose, 4-0-β-galactopyranosyl-D-fructose, is not normally present in raw milk unless milk reconstituted from powder has been added. It is formed by a process called epimerization. Epimerization of lactose in milk is a heat-induced process that causes a molecular rearrangement of lactose into a compound with the same molecular weight.

The article on UHT processing contains calculators that enable the effect of time/temperature treatments applied to milk to be modelled and the results integrated to predict the formation of lactulose and other compounds.

This simpler calculator enables the concentration of lactulose to be predicted after a single, defined heat treatment using 3-algorithms developed by Browning et at. (2001), Claeys et al. (2003) and Rombaut et al. (2002). All algorithms use the Arrhenius rate equation and use slightly different values for activation energy (E). Note that a value of E = 122 kJ/mol has been used in the algorithm reported by Browning et at. (2001).

 Investigate the effect of holding milk at elevated temperatures on the formation of lactulose Time , s Temperature, °C

Note the different methods were validated over defined temperature ranges and caution must be taken in extrapolating the results outside these ranges.

Typical values for lactulose production following the heat treatment of milk are given in Table 1.

 TABLE 1. Formation of lactulose  during heat treatment of milk at 135 to 150°C for 10 to 40 s Temperature , °C Time, s Content (mg/L) mean ± SD, n = 4 Lactulose 135 20 121.7 (8.69) 30 229.2 (27.60) 35 232.5(11.30) 40 303.3(10.60) 140 20 161.6 (4.17) 30 276.4 (27.30) 35 376.2 (25.20) 40 456.3 (27.50) 145 10 109.3 (31.70) 15 237.8(11.00) 20 344.9 (30.60) 30 650.1 (49.85) 150 10 168.2 (6.57) 15 326.5(16.02) 20 535.5 (29.52) 30 988.2 (34.50) Source: Montilla et al. (1996)

## References

Browning , E, Lewis, M. and McDougall, D. (2001) Predicting safety and quality parameters for UHT-processed milks. International J Dairy Technology. 54, 111-120.

Claeys, W., Van Loey, A., and Hendrickx, M. (2003). Kinetics of hydroxymethylfurfural, lactulose and furosine formation in milk with different fat content. Journal of Dairy Research. 70, 85-90.

Montilla, A., Calvo, M.M., Santa-Marıa, G., Corzo, N., and Olano, A.(1996). Correlation between lactulose and furosine in UHT-heated milk. J. Food Prot., 59:1061–1064.

Rombaut, R., Dewettinck, K., De Mangelaere, G., & Huyghebaert, A. (2002). Inactivation of heat resistant spores in bovine milk and lactulose formation. Milchwissenschaft. 57, 432–436.

## How to cite this calculator

Mullan, W.M.A. (2021) [On-line] Available from: Accessed: