β-Galactosidase activity of commercial lactase samples in raw and pasteurized milk at refrigerated temperatures

Horner, T.W.; Dunn, Michael L.; Eggett, Dennis L.; Ogden, Lynn V.

doi:10.3168/jds.2010-3742

Cited by 54 publications

(20 citation statements)

References 16 publications

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“…Horner et al [19] evaluated the lactose hydrolysis of raw and pasteurized milk using four commercial Kluyveromyces β -galactosidases at 2°C for 72 h. The authors observed that the fourfold increase in the enzyme concentration doubled the hydrolyzed lactose concentration in the milk after a 12 h reaction.…”

Section: Resultsmentioning

confidence: 99%

Lactose Hydrolysis in Milk and Dairy Whey Using Microbial β-Galactosidases

et al. 2015

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This work aimed at evaluating the influence of enzyme concentration, temperature, and reaction time in the lactose hydrolysis process in milk, cheese whey, and whey permeate, using two commercial β-galactosidases of microbial origins. We used Aspergillus oryzae (at temperatures of 10 and 55°C) and Kluyveromyces lactis (at temperatures of 10 and 37°C) β-galactosidases, both in 3, 6, and 9 U/mL concentrations. In the temperature of 10°C, the K. lactis β-galactosidase enzyme is more efficient in the milk, cheese whey, and whey permeate lactose hydrolysis when compared to A. oryzae. However, in the enzyme reaction time and concentration conditions evaluated, 100% lactose hydrolysis was not reached using the K. lactis β-galactosidase. The total lactose hydrolysis in whey and permeate was obtained with the A. oryzae enzyme, when using its optimum temperature (55°C), at the end of a 12 h reaction, regardless of the enzyme concentration used. For the lactose present in milk, this result occurred in the concentrations of 6 and 9 U/mL, with the same time and temperature conditions. The studied parameters in the lactose enzymatic hydrolysis are critical for enabling the application of β-galactosidases in the food industry.

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Section: Resultsmentioning

confidence: 99%

Lactose Hydrolysis in Milk and Dairy Whey Using Microbial β-Galactosidases

et al. 2015

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“…Hence, the temperature of 8°C for milk storing was selected mainly in order to limit the growth of psy-chrotrophic microflora and to preserve the activity of lactase. The lactase of K. lactis source shows an increase in the activity of 85-95% at 38°C as compared to that measured at 4-5°C (Mlichová and Rosenberg, 2006; Horner et al ., 2011). In the cheese making process the increase of temperature during milk warming (35°C) and the cooking of curd (42°C), allow the complete hydrolysis of the residual lactose before the curd acidification drops pH below 5.5, limiting the activity of the lactase.…”

Section: Discussionmentioning

confidence: 99%

“…The high concentration of lactase needed was probably due to the specific operative conditions rather than the use of raw sheep’s milk. In cow’s milk, no differences have been observed in lactase activity in relation to the type of milk (raw or pasteurized) or in relation to milk fat content (Horner et al ., 2011). The only modification proposed in the manufacturing of lactose-free variants of Pecorino di Osilo , fresh ricotta and Ricotta mustia cheeses, was the replacement of raw sheep’s milk with the lactose-free sheep’s milk.…”

Section: Discussionmentioning

confidence: 99%

“…Low-lactose and lactose-free products are obtained in the dairy industry by the hydrolysis of lactose in milk using the enzyme beta-galactosidase (lactase), by chromatographic separations or by use of membrane separation, that could be also combined with lactose hydrolysis techniques (Jelen and Tossavainen, 2003). The hydrolysis of lactose, obtained by means of free or immobilized lactase (Horner et al ., 2011), can influence both the technological and the sensorial properties of products. Lactose hydrolysis could also results in transgalactosylation reactions, in which glucose and galactose released by hydrolysis served as galactosyl acceptors, producing oligosaccharides with prebiotic activity.…”

Section: Introductionmentioning

confidence: 99%

“…Mesophilic lactase show the highest activity at ca . 30°C, while thermostable lactases are effective until 50-65°C and temperature <15°C are needed for cold-active lactases (Mlichová and Rosenberg, 2006; Horner et al ., 2011). The EU regulatory framework governing lactose-free foods (or low lactose foods) has just been changed (European Commission, 2013).…”

Section: Introductionmentioning

confidence: 99%

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Production of farmstead lactose-free Pecorino di Osilo and ricotta cheeses from sheep’s milk

et al. 2017

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The present work was aimed to define and validate farmstead production of lactose-free Pecorino di Osilo cheese, fresh ricotta cheese, and salted and smoked ricotta cheese (Ricotta mustia). The enzymatic activity of the commercial preparation containing lactase (1.1 g/mL), preliminarily tested using a spectrophotometric titration, showed activity equal to 4950±40 neutral lactase unit/g. The amount of lactase required to obtain the lactose-free milk was then established in triplicate laboratory trials, by adding the enzyme at concentrations of 0.7, 0.9 and 1.1 g/L in flasks containing 160 mL of raw sheep’s milk. Samples were incubated under conditions expected during milk storage and cheese-making. The residual lactose content in milk was determined by enzymatic method. The addition of lactase at concentration of 1.1 g/L of milk reduced the lactose concentration below the limit of detection (LOD) of 0.06 g/L. The procedure was validated at a dairy farm, using three different batches of bulk raw sheep’s lactose-free milk that were transformed into Pecorino di Osilo cheese. The resulting whey was used to produce fresh ricotta and Ricotta mustia cheese. Raw milk and whey samples were always below lactose detection limit. The residual lactose was measured in Pecorino di Osilo cheese, after 24 hours and 30 days from production; in fresh ricotta cheese, after 48 hours; in Ricotta mustia cheese after 7 days. The determination of lactose content in cheese samples was conducted by a gas chromatography-flame ionization detection method, which showed a LOD and limit of quantification respectively of 1.8 and 5.6 mg/kg for cheese, and 1.35 and 4.2 mg/kg for both ricotta cheeses. The lactose concentration was always below the relevant LOD values in all samples. The mean concentration of galactose and glucose were respectively 13,000±2000 and 11,000±2000 mg/kg in fresh Pecorino di Osilo, 1100±300 and 1200±300 mg/kg in fresh ricotta, and 950±400 and 750±250 mg/kg in Ricotta mustia. The results of the present study showed that the production of farmstead lactose-free Pecorino di Osilo cheese and ricotta cheeses from raw sheep’s milk is easily achievable. The main issue for farmstead production of artisanal lactose-free products is the implementation of permanent procedures based on hazard-analysis and critical control principles aimed at guaranteeing the effectiveness of the process and at acquiring analytical evidences to demonstrate the fulfilment of law requirements for labelling.

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