Immobilization of lactase for the continuous hydrolysis of whey permaete

Illanes, Andrés; Ruiz, A.; Zúñiga, Marı́a Elvira; Aguirre, Carolina; O'Reilly, Sybil; Curotto, E.

doi:10.1007/bf00369375

Cited by 44 publications

(10 citation statements)

References 5 publications

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“…Despite the obvious advantage of this type of process, the preferred method for producing delactosed milk consists in hydrolyzing the milk already packed in the carton and let it react during storage until enzyme deactivation (Gänzle et al 2008). β-galactosidase has also been used in the upgrading of whey (and permeate) as ingredients of food and feed and in the production of sugar substitutes from permeate (Knopf et al 1979, Illanes et al 1990b). The production of high-fructose syrups by a sequential enzymatic process of hydrolysis and isomerization of whey permeate with immobilized β-galactosidase and glucose isomerase has been developed, obtaining a product of similar sweetening power than sucrose (Illanes et al 1999), which represents an option for sugar-importing countries (Marwaha and Kennedy, 1988).…”

Section: Upgrading By Enzymatic Hydrolysismentioning

confidence: 99%

Whey upgrading by enzyme biocatalysis

Illanes¹

2011

Electro Journal of Biotech

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Whey is a co-product of processes for the production of cheese and casein that retains most of the lactose content in milk. World production of whey is estimated around 200 million tons per year with an increase rate of about 2%/per year. Milk production is seasonal, so surplus whey is unavoidable. Traditionally, whey producers have considered it as a nuisance and strategies of whey handling have been mostly oriented to their more convenient disposal. This vision has been steadily evolving because of the upgrading potential of whey major components (lactose and whey proteins), but also because of more stringent regulations of waste disposal. Only the big cheese manufacturing companies are in the position of implementing technologies for their recovery and upgrading, so there is a major challenge in incorporating medium and small size producers to a platform of whey utilization, conciliating industrial interest with environmental protection within the framework of sustainable development. Within this context, among the many technological options for whey upgrading, transformation of whey components by enzyme biocatalysis appears as prominent. In fact, enzymes are green catalysts that can perform a myriad of transformation reactions under mild conditions and with strict specificity, so reducing production costs and environmental burden. This review pretends to highlight the impact of biocatalysis within a platform of whey upgrading. Technological options are shortly reviewed and then an in-depth and critical appraisal of enzyme technologies for whey upgrading is presented, with a special focus on newly developed enzymatic processes of organic synthesis, where the added value is high, being then a powerful driving force for industrial implementation.

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Section: Upgrading By Enzymatic Hydrolysismentioning

confidence: 99%

Whey upgrading by enzyme biocatalysis

Illanes¹

2011

Electro Journal of Biotech

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“…CPBR with chitin-immobilized β-galactosidase (Illanes et al 1998a) is presented to illustrate enzyme reactor design under modulated thermal inactivation. Diffusional restrictions are in this case negligible, the enzyme is inhibited by the product galactose competitively and neither glucose nor lactose at high concentrations are inhibitors (Illanes et al 1990), so that Fig. 5.14 simplifies to the scheme in Fig.…”

Section: Reactor Design and Performance Under Modulated Enzyme Inactimentioning

confidence: 99%

Enzyme Reactors

Illanes

Altamirano

2008

Enzyme Biocatalysis

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More than 80% of the commercial value of enzymes is linked to their applications as process catalysts. Hydrolytic reactions conducted mainly with the enzyme dissolved in the aqueous medium has been the traditional way of using enzymes, this technology still representing a major share of enzyme processes. However, in recent decades the use of enzymes in organic synthesis has widened its scope of application to unprecedented levels.Enzyme reactors can operate batch-wise or continuously; fed-batch operation has also been proposed (Kumar et al. 1996). Batch processes with the enzymes (usually hydrolases) dissolved in an aqueous reaction medium, despite its wide application have several drawbacks, since enzymes are poorly stable and hard to recover in such systems, leading to low productivity; besides, such processes are characterized by a rather low added value so that process optimization is critical for being and keeping competitive. Poor stability is usually the limiting factor in any enzyme process so that enzyme stabilization during reactor operation is a major concern (Ballesteros et O'Fágáin 2003) and among the many strategies for enzyme stabilization (Illanes 1999) enzyme immobilization is the most relevant (Guisán 2006). Immobilized enzymes can be used in batch processes but in this case the enzyme is recovered to be used in subsequent batches until the accumulated inactivation makes necessary to replace the spent biocatalyst. As a consequence, specific productivity (mass of product/mass of biocatalyst · time of operation) is increased and bioreactor design becomes flexible to suit the particular needs of a given process.Immobilized enzymes, despite the complexities introduced by the heterogeneous nature of the catalytic process, are usually much more stable than their soluble

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“…Values for kinetic parameters at operating pH and temperature are in Table 1 [29]. Chitin is an impervious material [30] and external diffusional restrictions are negligible [25], so that kinetic parameters can be considered inherent.…”

Section: Enzyme Kineticsmentioning

confidence: 99%

Design of immobilized enzyme reactors for the continuous production of fructose syrup from whey permeate

Illanes

Wilson

Raiman

1999

Bioprocess Engineering

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Biocatalyst inactivation is inherent to continuous operation of immobilized enzyme reactors, meaning that a strategy must exist to ensure a production of uniform quality and constant throughput. Flow rate can be pro®led to compensate for enzyme inactivation maintaining substrate conversion constant. Throughput can be maintained within speci®ed margins of variation by using several reactors operating in parallel but displaced in time. Enzyme inactivation has been usually modeled under non-reactive conditions, leaving aside the effect of substrate and products on enzyme stability. Results are presented for the design of enzyme reactors under the above operational strategy, considering ®rst-order biocatalyst inactivation kinetics modulated by substrate and products. The continuous production of hydrolyzed-isomerized whey permeate with immobilized lactase and glucose isomerase in sequential packed-bed reactors is used as a case study. Kinetic and inactivation parameters for immobilized lactase have been determined by the authors; those for glucose isomerase were taken from the literature. Except for lactose, all other substrates and products were positive modulators of enzyme stability. Reactor design was done by iteration since it depends on enzyme inactivation kinetics. Reactor performance was determined based on a preliminary design considering non-modulated ®rst-order inactivation kinetics and confronted to such pattern. The new pattern of inactivation was then used to redesign the reactor and the process repeated until reactor performance (considering modulation) matched the assumed pattern of inactivation. Convergence was very fast and only two iterations were needed. List of symbolsA m 2 cross sectional area of reactor a kat/kg speci®c activity of catalyst D m reactor diameter d s total operation time for each reactor cycle E kat enzyme activity e kat/m 3 volumetric enzyme activity F m 3 /s total process¯ow rate F 0i m 3 /s initial feed¯ow-rate to each reactor H number of enzyme half-lives used in the reactor H b m catalyst bed height H R m reactor height K eq kg-mole/m 3 equilibrium constant of glucose isomerization to fructose ( V G K F aV F K G ) K F kg-mole/m 3 IGI Michaelis constant for fructose K G kg-mole/m 3 IGI Michaelis constant for glucose K L kg-mole/m 3 CIL Michaelis constant for lactose K P kg-mole/m 3 CIL competitive inhibition constant for galactose k cat catalytic rate constant for lactose hydrolysis k H cat catalytic rate constant for glucose isomerization k D s À1 ®rst-order inactivation rate constant under no modulation k DJ s À1 ®rst-order inactivation rate constant under modulation by J M kg catalyst mass N 1 ± CIL global modulation factor N 2 ± IGI global modulation factor N R ± number of reactors n L ± CIL modulation factor by lactose n P ± CIL modulation factor by galactose n G ± IGI modulation factor by glucose n F ± IGI modulation factor by fructose R F ± ratio of minimum to maximum ow rate s 0 kg-mole/m 3 feed lactose concentration t s time of operation t s s time interval between e...

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Immobilization of lactase for the continuous hydrolysis of whey permaete

Cited by 44 publications

References 5 publications

Whey upgrading by enzyme biocatalysis

Whey upgrading by enzyme biocatalysis

Enzyme Reactors

Design of immobilized enzyme reactors for the continuous production of fructose syrup from whey permeate

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