Effect of temperature and concentration of βeta-galactosidase on the composition of reduced lactose pasteurized goat milk

Nkarthe Guerra Araújo,Ricardo Targino Moreira,José Barros Da Silva,Haíssa Roberta Cardarelli

doi:10.1590/fst.05220

Nkarthe Guerra Araújo, Ricardo Targino Moreira + Show 2 more

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https://doi.org/10.1590/fst.05220

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Abstract

Abstract This study evaluated the influence of temperature and β-galactosidase concentration on lactose hydrolysis and on the composition of pasteurized goat milk. Goat milk was pasteurized at 75 °C/15 s and cooled to 10 °C and 30 °C, received 0 (control); 0.04%; 0.07%; 0.20% (v/v) β-galactosidase and was incubated for 5 h, followed by enzymatic inactivation at 85 °C. The hydrolysis degree, pH and acidity were evaluated hourly. Physico-chemical parameters were determined after hydrolysis. The maximum hydrolysis degree (100%) has been reached in 4 h when using 0.07% and 0.20% lactase concentrations at 30 °C; however, the minimum hydrolysis percentage of 70% has been reached at 10 °C for all lactase concentrations tested since 1 h of incubation. The degree of hydrolysis and the total acidity of pasteurized goat milk increased with temperature. Low lactase concentrations resulted in an increase in protein levels, total casein, density, total and defatted dry extract. Therefore, combination of low lactase levels and hydrolysis at 10 °C promoted positive changes in lactose-free pasteurized goat milk. This study was the first reporting the changes resulting from enzymatic hydrolysis in the composition of pasteurized goat milk.

Highlights

Goat milk production and commercialization is traditional in South America; it has been affected by continuous regional economic fluctuations
These results showed that hydrolysis using higher lactase concentrations at 30 °C is higher in a shorter time interval, the hydrolysis percentage surpasses 70% using the temperature of 10 °C for all lactase concentrations tested at all incubation time intervals
The results obtained in this study using only the enzymatic hydrolysis process during the 5h period were satisfactory when compared to the findings of Antunes et al (2014), which obtained 0.2 g/100 mL lactose in skimmed bovine milk subjected to enzymatic hydrolysis using 0.4 mL/L lactase from Kluyveromyces lactis for 21 h at 10 ± 1 °C, followed by the microfiltration process

Summary

Introduction

Goat milk production and commercialization is traditional in South America; it has been affected by continuous regional economic fluctuations. The prevalence of diseases related to the consumption of certain foods has increased considerably in recent years, with lactose intolerance and bovine milk protein allergy being the most frequent Excluding this product from the diet is the main recommendation of health professionals. Research related to goat milk has indicated that its proteins as well as the peptides produced from them have important biological activity such as antimicrobial, immunomodulator, antioxidant, hypocholesterolemic and antihypertensive activities (Medeiros et al, 2018; Mal et al, 2018) It has better digestibility, greater bioavailability of iron and magnesium and higher calcium and copper content than bovine milk (Lucatto et al, 2020; Fangmeier et al, 2019). The composition of long-chain fatty acids in its fraction of monounsaturated and polyunsaturated fatty acids (ω-6 and ω-3 fatty acids, eicosapentaenoic acid- EPA and docosahexaenoic acid- DHA, and medium-chain triglycerides) present in goat milk which are considered beneficial to human physiology surpasses bovine milk, (Hodgkinson et al, 2018); and is rich in niacin, thiamine, riboflavin, and pantothenate (Ranadheera et al, 2019)

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