Lactase Preparations Research Articles

Insight into protein cross-linking and casein polymerization in pre- and post-hydrolyzed lactose-free UHT milk during long-term storage

During processing and storage of both conventional and lactose-hydrolyzed UHT milk (LHM), aggregation of milk proteins occurs. Protein aggregation can inter alia occur via non-reducible covalent cross-links derived from either Maillard or dehydroalanine (DHA) pathways. To study this further in relation to processing method and lactase enzyme purity, LHM was produced using 3 different lactase preparations, with lactase enzymes added in a dairy setting either before (pre-hydrolysis) or after (post-hydrolysis) UHT treatment. The prepared LHM types were subsequently stored at either 25°C or 35°C for up to one year. Mass spectrometry was used to absolutely quantify the level of furosine, N-ɛ-(carboxymethyl)lysine (CML) and N-ɛ-(carboxyethyl)lysine (CEL), lanthionine (LAN) and lysinoalanine (LAL) in these products using a newly developed method on Triple Q for these processing-induced markers. The results showed higher levels of Maillard related processing markers in pre-hydrolyzed LHM compared with post-hydrolyzed LHM and conventional UHT milk which, on the other hand, contained higher concentrations of DHA-derived cross-links. Proteomics of collected particles from asymmetrical flow field-flow fractionation (AsFlFFF) in combination with gel electrophoresis indicated presence of intra-micellar cross-links during storage, for especially larger particles involving αS1- and αS2-caseins.

Impact of hydrolysis method and lactase preparation on proteolysis and glycation in long-term stored lactose-hydrolysed UHT milk

Shorter shelf-life of lactose-hydrolysed UHT milk (LHM) can be linked to lactase purity both due to unwanted proteolytic activity and Maillard reactions. To study this, pre- and post-hydrolysed milk was added one of three types of lactase enzymes of increasing purity (A, B and C), and stored for up to 1 year at 25 or 35 °C. Proteolytic side-activities in post-hydrolysed milk depended on lactase purity, with lactase A causing the highest proteolysis. The lowest proteolytic activity occurred with lactase C in both pre- and post-hydrolysed milk. LHM with lactase A exhibited proteolysis in C-terminal regions of major milk proteins, particularly in post-hydrolysed milk, which also showed endopeptidase activity. Glycation initiated by UHT treatment was higher in pre-hydrolysed milk than in post-hydrolysed milk, but subsequent storage led to similar glycation levels in both. Therefore, using post-hydrolysis with highly purified lactases, proteolytic side-activities can be lowered and glycation can be delayed.

Молекулярно-генетична концепція формування психотипів особистості в дітей при ожирінні, асоційованому з лактозною інтолерантністю

Мета дослідження — визначення асоціації однонуклеотидних поліморфізмів (SNP) у гені лактази (LCT) із формуванням ожиріння в дітей на основі вивчення особистісної та реактивної тривожності (тест Спілбергера — Ханіна) та оцінки якості життя (методика MOS-SF-36). Матеріали та методи. Проведено генотипування за поліморфним локусом енхансера гена MCM6 (minichromosome maintenance complex component 6), що кодує експресію гена LCT у 62 дітей віком 12–18 років із різними формами ожиріння. До першої групи (n = 31) увійшли діти, які мали рецесивну алель С/С 13910 поліморфізму rs4988234. Другу групу (n = 31) становили діти з домінантною гомозиготною алеллю Т/Т 13910 або гетерозиготною алеллю С/Т 13910. Результати. Установлено 6-кратне збільшення частоти зустрічальності генотипу С/С 13910 у дітей із тяжкими формами ожиріння (індекс маси тіла > 97-го перцентиля). Доведено наявність високого рівня особистісної (46,5 ± 0,4) та середнього рівня реактивної тривожності (33,2 ± 0,9) у дітей із генотипом С/С 13910 порівняно з помірно високим рівнем особистісної (37,5 ± 0,8) та низьким рівнем реактивної тривожності (24,3 ± 0,8) у пацієнтів із генотипами С/Т та Т/Т 13910 (р < 0,05). Наведено результати оцінки якості життя підлітків з ожирінням, що характеризуються погіршенням рівня фізичного компонента (РН) здоров’я при генотипі С/С 13910, а саме в юнаків за рахунок зниження показника рольового функціонування, обумовленого фізичним станом (RP), у дівчат за рахунок зниження рівня загального здоров’я (GH), р < 0,05. Висновки. Таким чином, дослідження однонуклеотидних поліморфізмів у гені LCT (rs4988234) виявило асоціацію генотипу С/С 13910 із тяжкими формами абдомінального ожиріння в дітей (індекс маси тіла > 97-го перцентиля), підвищеним рівнем тривожності та зниженням оцінки якості життя за рахунок фізичного компонента здоров’я, що може бути використане при моделюванні поведінкової інтервенції та потребувати можливої замісної терапії препаратами екзогенної лактази.

Експресія мРНК галектину-9 при ожирінні у дітей з поліморфізмами гена лактази

Мета. Вивчення асоціації експресії мРНК галектину-9 (Gal-9) та мальабсорбції лактози при ожирінні у дітей з поліморфізмами (SNP) гена лактази (LCT) та дослідження ефективності лікування лактазної недостатності з використанням препаратів екзогенної лактази. Матеріали та методи. Обстежено 70 дітей з ожирінням (індекс маси тіла > 95-го перцентиля), а також 16 дітей без ожиріння віком 6–18 років. Визначено SNP LCT (матеріал для дослідження — венозна кров) методом полімеразної ланцюгової реакції (ПЛР) у реальному часі, експресії мРНК Gal-9 (матеріал для дослідження — букальний епітелій) методом ПЛР у реальному часі зі зворотною транскрипцією, дослідження мальабсорбції лактози за допомогою водневого дихального тесту. Серед дітей з ожирінням першу групу спостереження становили 38 дітей з генотипом С/С 13910, другу групу — 32 дитини з фенотипово ідентичними генотипами С/Т 13910 та Т/Т 13910, р > 0,05. У дітей з першої групи спостереження також визначався рівень експресії мРНК Gal-9 та мальабсорбції лактози після використання препаратів екзогенної лактази. Результати. Генотип С/С 13910 реєструвався у 38 (54,3 %), генотип С/Т 13910 — у 22 (31,4 %), генотип Т/Т — у 10 (14,3 %) пацієнтів. Мальабсорбція лактози у дітей з генотипом С/С 13910 становила в середньому 32,7 ± 10,4 рmm, у дітей з генотипами С/Т 13910 — 26,3 ± 4,9 рmm (р > 0,05), при генотипі Т/Т 13910 та у дітей без ожиріння була відсутня (р < 0,05). Середній рівень експресії мРНК Gal-9 у дітей з генотипом С/С 13910 дорівнював 564,3 ± 32,8 УО ∆mRNA Gal-9/mRNA actin, у дітей з генотипами С/Т і Т/Т 13910 — 61,04 ± 15,30 УО ∆mRNA Gal-9/mRNA actin, р < 0,01. Важливим є той факт, що в підгрупі дітей з генотипом С/С 13910 і мальабсорбцією лактози (n = 20) зареєстрований найнижчий середній рівень експресії мРНК Gal-9 (42,47 ± 13,30 УО ∆mRNA Gal-9/mRNA actin), тоді як у підгрупі дітей з генотипом С/С 13910 без мальабсорбції лактози (n = 18) — найвищий (1086,73 ± 52,60 УО ∆mRNA Gal-9/mRNA actin), що перебільшив рівень експресії мРНК Gal-9 у дітей без ожиріння та мальабсорбції лактози (313,34 ± 19,70 УО ∆mRNA Gal-9/mRNA actin), р < 0,01. Після використання препаратів екзогенної лактази у дітей з генотипом С/С 13910 та мальабсорбцією лактози протягом 1 місяця рівень експресії мРНК Gal-9 наблизився до рівня 246,21 ± 15,70 УО ∆mRNA Gal-9/mRNA actin, тоді як при використанні лише низьколактозної дієти збільшився незначно — до 58,72 ± 21,10 УО ∆mRNA Gal-9/mRNA actin, р < 0,01. Цікаво, що у дітей з генотипом С/С 13910 без мальабсорбції лактози на фоні низьколактозної дієти рівень експресії мРНК Gal-9 знизився до рівня 388,38 ± 20,40 УО ∆mRNA Gal-9/mRNA actin, наблизившись до рівня здорових дітей без ожиріння. Висновки. У дітей з генотипом С/С 13910 рівень експресії мРНК Gal-9 залежить від мальабсорбції лактози, яка потребує замісної терапії, що поєднує низьколактозну дієту та використання препаратів екзогенної лактази. За відсутності мальабсорбції лактози використання лише низьколактозної дієти у дітей з генотипом С/С 13910 наближає рівень експресії мРНК Gal-9 до рівня здорових дітей без ожиріння.

Understanding the effect of storage temperature on the quality of semi-skimmed UHT hydrolyzed-lactose milk: an insight on release of free amino acids, formation of volatiles organic compounds and browning

Proteolytic side activity of the lactase preparations (LPs) intended for ultra-high temperature hydrolyzed-lactose milk (UHLM) production induces changes in the product quality during shelf-life. The problem is particularly relevant when the enzyme is added aseptically in the packaging (“in pack” process), while the negative quality effects can be mitigated following the “in batch” process adding the LP before thermal sterilization. In this study, we monitored the quality over time of UHLM produced “in batch” and stored at 4, 20, 30 and 40 °C focusing on proteolysis, volatiles organic compounds (VOCs) formation and color changes. The goal was to identify the key reactions and compounds relevant for the product quality. An increase in storage temperature determined significant changes in the free amino acids profile increasing Strecker aldehydes and methyl ketones formation. At 30 and 40 °C, Maillard reaction and lipid oxidation ended up in a modification of the milk color, whereas at 4 and 20 °C no significant alteration was observed. Altogether, the results suggested a coordinate involvement of Maillard reaction, protein and lipid oxidation to milk browning and off-flavors formation in UHLM.

Identification and characterization of proteinase B as an unstable factor for neutral lactase in the enzyme preparation from Kluyveromyces lactis

The stability of the commercial lactase enzyme is important for the dairy industry. A destabilizing factor for neutral lactase in the enzyme preparation from Kluyveromyces lactis was investigated. We found that lactase had lower thermal stability when fragmented bands of lactase were confirmed on SDS-PAGE. After the destabilizing factor of lactase was purified, that was identified by BLAST search as a hypothetical protein in K.lactis similar to proteinase B (PRB) of Saccharomyces cerevisiae. The molecular mass of protease was estimated to be approximately 30kDa with SDS-PAGE. The purified protease exhibited activity toward lactase and FITC-casein but not toward bovine serum albumin or milk casein. The optimal pH and temperature of the protease were 8.0 and 40°C, respectively. The protease activity was strongly inhibited by Fe2+, Cu2+, and a serine protease inhibitor, but activated by Ca2+. Based on these properties, the protease was identified as PRB. Lactase fragmentation was accelerated by the addition of purified PRB to the lactase preparation and was suppressed by protease inhibitors. Thus, this is the first report to identify and characterize PRB as the unstable factor of neutral lactase in the K.lactis preparation.

Chemical and sensory changes during shelf-life of UHT hydrolyzed-lactose milk produced by “in batch” system employing different commercial lactase preparations

Manufacturing shelf-stable Ultra-high temperature hydrolyzed-lactose milk (UHLM) is a challenge for dairy producers, as the product undergoes chemical changes during storage due to both reducing sugars reactivity and proteolysis arising from the impurity of the lactase preparations. In the present study, the “in batch” production system, which includes the addition of the lactase before the thermal treatment, was demonstrated a valuable alternative to the more popular “in pack” system, where lactase is added directly into each milk package after thermal sterilization. The features of the technology were investigated by monitoring the changes in free amino acids, volatile organic compounds, color and sensory properties of UHLMs produced with three different lactase preparations (LPs), up to 120 days at 20 °C. Upon UHT processing, the proteolytic side activity of lactases was minimized, so minimum breakdown of milk protein was achieved. The release of free amino acids was dependent on the lactase purity only in the early production phases, whereas it did not change over time. The Strecker aldehydes benzaldehyde and 2-methylbutanal resulted as effective markers to correlate with the initial lactase purity during storage. Color and sensory slightly changed during storage but were poorly correlated with the different lactases, resembling to phenomena typical of milk aging. This latter result suggested that production costs might be lowered by opting for less-purified lactases when considering the “in batch” technology, supporting the application of this production system for the design of UHLM with high-quality standards and low risk of alterations during shelf-life.

Application of PTR-TOF-MS for the quality assessment of lactose-free milk: Effect of storage time and employment of different lactase preparations.

Lactose-free dairy products undergo several chemical modifications during shelf life because of the reactivity of glucose and galactose produced by the lactose enzymatic hydrolysis. In this study, proton transfer reaction-mass spectrometry (PTR-MS), coupled with a time-of-flight (TOF) mass analyzer, was applied to get an insight on the phenomena occurring during the shelf life of ultrahigh-temperature (UHT) lactose-free milk (LFM). UHT LFMs produced by three different commercial lactase preparations were evaluated during storage at 20°C over a 150 days period, sampling the milk every 30 days. Production was repeated three times, on three consecutive weeks, in order to take milk variability into consideration. Principal component analysis applied to the whole "volatilome" data demonstrated the capability of PTR-TOF-MS in detecting the milk batch-to-batch variability: Freshly produced milk samples were distinguished based on the week of production at the beginning of shelf life. Additionally, a clear evolution of the volatiles organic compounds (VOCs) profiling during storage was highlighted. Further statistical analysis confirmed VOCs temporal evolution, mostly because of changes in methyl ketones concentration. Differences caused by the commercial lactases did not emerged, except for benzaldehyde. Altogether, data demonstrated PTR-TOF-MS analysis as a valuable and rapid method for the detection of changes in the VOCs profiling of UHT LFM.

One-step Removal of Proteases in a Commercial Lactase Preparation from <i>Kluyveromyces lactis</i> Using an Anion-exchange Membrane

One-step Removal of Proteases in a Commercial Lactase Preparation from <i>Kluyveromyces lactis</i> Using an Anion-exchange Membrane

A new β-galactosidase extracted from the infant feces with high hydrolytic and transgalactosylation activity.

A β-galactosidase (β-GalINF) was directly isolated from feces of an 8-month-old infant. Mass spectrum analysis showed β-GalINF with coverage over 50% to the β-galactosidase from Bifidobacterium longum EK3. Accordingly, the β-galINF was amplified from the feces metagenomic DNA by degenerate primers. After overexpressed in Escherichia coli, the β-GalINF was purified and biochemical characterized. β-GalINF existed as homotetramer and homodimer, whose activity (optimal at 50 °C, pH 6.5) was exhilaratingly increased to 484% by artificial intestinal juice. The Km and Vmax values for oNPG and lactose were 20.95 ± 2.76 mM, 5004.50 ± 318.8 μmol min-1 mg-1 and 140.2 ± 17.7 mM, 293.1 ± 14.7 μmol min-1 mg-1, respectively. The production rate of galacto-oligosaccharides by β-GalINF from 20% lactose at 50 °C was 33.4 ± 0.67%. These results suggested the β-GalINF with high hydrolytic and transgalactosylation activity from the infant intestinal has great potential as infant lactase preparation. Moreover, this study provided a new way for exploring undetected enzymes by uncultured-dependent methods.

Interplay between Residual Protease Activity in Commercial Lactases and the Subsequent Digestibility of β-Casein in a Model System.

One of the conventional ways to produce lactose-hydrolyzed (LH) milk is via the addition of commercial lactases into heat-treated milk in which lactose is hydrolyzed throughout storage. This post-hydrolysis method can induce proteolysis in milk proteins due to protease impurities remaining in commercial lactase preparations. In this work, the interplay between lactose hydrolysis, proteolysis, and glycation was studied in a model system of purified β-casein (β-CN), lactose, and lactases using peptidomic methods. With a lactase presence, the proteolysis of β-CN was found to be increased during storage. The protease side-activities mainly acted on the hydrophobic C-terminus of β-CN at Ala, Pro, Ile, Phe, Leu, Lys, Gln, and Tyr positions, resulting in the formation of peptides, some of which were N-terminal glycated or potentially bitter. The proteolysis in β-CN incubated with a lactase was shown to act as a kind of “pre-digestion”, thus increasing the subsequent in vitro digestibility of β-CN and drastically changing the peptide profiles of the in vitro digests. This model study provides a better understanding of how the residual proteases in commercial lactase preparations affect the quality and nutritional aspects of β-CN itself and could be related to its behavior in LH milk.

TREATMENT OF LACTASE DEFICIENCY IN CHILDREN’S OBESITY WITH GENOTYPE C/C 13910 OF LACTASE GENE

Introduction: Excess lactose in the diet of modern man causes the development of not only lactase deficiency, but it can be a factor that contributes to obesity. The aim: To study associations between obesity and genotype C/C 13910 of lactase gene (LCT) in children, to investigate the effectiveness of treatment using drug exogenous lactase and a low-lactose diet. Materials and methods: genotyping of lactase gene by real-time polymerase chain reaction, determining the level of lactose maldigestion by hydrogen breath test (HBT), estimating the insulin resistance with the HOMA-IR index in 70 obese children and 40 healthy children 6 - 18 years. Obese children with genotype C/C 13910 and lactose maldigestion (n=40) were randomized in two groups: children from group I (n=20) received an exogenous lactase preparation, and children from group II (n=20) - low-lactose diet. Results: in obese children, the genotype C/C 13910 is 2 times more often than in healthy children. Obese children with genotype C/C 13910 have a significantly higher value of HBT (32.8-39.8 ppm) compared to healthy children (p<0.05), and an increased value of the HOMA-IR index. After treatment, there was a significant decrease in HBT and the HOMA-IR index in the two comparison groups. Conclusions: signs of insulin resistance are observed in children with obesity, genotype C/C 13910 and lactose maldigestion. The use of exogenous lactase in the therapy or the administration of a low-lactose diet cause approximately the same decrease in the HOMA-IR index.

Proteolytic side-activity of lactase preparations

Storage-induced changes in hydrolysed-lactose (LH) ultra-high-temperature (UHT)-treated milk were studied using proteomics. Five commercial lactase preparations were used to hydrolyse lactose in semi-skimmed milk after UHT treatment. The proteolytic side-effects of lactase preparations on UHT milk during storage for up to 60 days were compared with their effects on conventional UHT milk. The level of free amino groups increased more during storage in all LH UHT milk samples than in conventional UHT milk. The increase was partly ascribed to the release of C-terminal amino acid residues from intact β- and αS1-casein, indicating carboxypeptidase activity. During storage, three of the enzyme preparations increased release of peptides derived from the hydrophobic regions of β- and αS1-casein, which could potentially contribute to development of bitterness in the milk samples. The authors propose that residual protease side-activity in the lactase preparations accelerate product deterioration and decrease shelf-life of LH UHT milk.

The Differentiated Approach to the Treatment of Lactase Deficiency and Allergies to Cow's Milk Protein in Infants

One of the most common pathologies in infants is a lactase deficiency and allergy to cow's milk protein. Treatment of lactase deficiency and allergies to cow's milk protein in young children requires a differentiated approach. The best food for the child's first months of life is mother's milk provides adequate development of the child's body. The use of lactase preparations, such as LAKTAZAR® with lactase deficiency pathogenetically justified and allows a short time to eliminate its main clinical manifestations, while retaining the possibility of breastfeeding.

A combination of acid lactase from Aspergillus oryzae and yogurt bacteria improves lactose digestion in lactose maldigesters synergistically: A randomized, controlled, double-blind cross-over trial

Lactose digestion can be improved in subjects with impaired or completely absent intestinal lactase activity by administration of lactase preparations and particularly of acid lactase, which is active in the stomach, or by yogurt containing live lactic acid bacteria. It is the question, if lactose digestion can be further enhanced by combining these two approaches. We investigated in a randomised, placebo-controlled, double-blind, 5-arm crossover study on 24 lactose malabsorbers with variable degrees of lactase deficiency if different lactase preparations and freeze-dried yogurt culture affect gastrointestinal lactose digestion after consuming moderate amounts of lactose (12.5 g) by assessing hydrogen exhalation over 6 h. Furthermore, symptoms of lactose intolerance (excess gas production, abdominal pain, diarrhoea or nausea) were assessed using validated questionnaires. All preparations increased lactose digestion and reduced peak hydrogen exhalation by -27% (yogurt), -29/-33% (3300/9000 FCC(1) ((1) One FCC hydrolyses about 5 or 1.7-2.5 mg lactose in aquous solution or in (artificial) chyme, respectively, according to the FCC-III method of the Committee on Codex Specifications, Food and Nutrition Board, National Research Council. Food Chemicals Codex, 3rd edition. Washington, DC, National Academy Press, 1981 It cannot precisely be defined how much lactose can be hydrolysed in vivo by the consumption of a certain number of FCC units.) units acid lactase from Aspergillus oryzae) or -46%, respectively (3300 FCC units lactase plus yogurt culture combined), as compared with placebo (p < 0.001, Friedman test). The combination preparation had not only the strongest effect, but also showed the lowest variance in H(2)-exhalation values (less malabsorbers with no reduction of H(2)-exhalation) Apart from this, both the higher dose lactase and the combination preparation significantly reduced the symptoms most closely associated with H(2)-exhalation, namely flatulences and abdominal pain, respectively. The combined administration of freeze-dried yogurt cultures and acid lactase increases lactose digestion more than either freeze-dried yogurt cultures or acid lactase alone, and more lactose malabsorbers benefited from this effect.

Synthesis of Galactooligosaccharides in the Cheese Whey-based Medium by a Lactase from Lactobacillus paracasei YSM0308

An enzyme <TEX>${\beta}$</TEX>-galactosidase or <TEX>${\beta}$</TEX>-galactohydrolase [EC3.2.1.23], commonly called lactase, mediates galacto-oligosaccharide (GOS) synthesis under conditions of high substrate concentrations. Also, lactase hydrolyzes <TEX>${\beta}$</TEX>(<TEX>$1{\rightarrow}4$</TEX>) lactose into glucose and galactose, the latter is successively transferred to free lactose to make various oligosaccharides via transgalactosylation. GOS is non-digestible to human digestive enzymes and has been used as a functional prebiotics. Among the 24 lactic acid bacteria (LAB) strains used, Lactobacillus paracasei YSM0308 was selected based on its exhibition of the highest <TEX>${\beta}$</TEX>-galactoside hydrolysis activity, and the crude lactase was prepared for examination of reaction conditions to affect the GOS synthesis. Lactase activity was measured with a spectrophotometer using ONPG (o-nitropheyl <TEX>${\beta}$</TEX>-D-galactopyranoside) method. Lactase activity was not detected in the culture supernatant and was mostly present in the cell pellet after centrifugation. Activity of the crude lactase preparation ranges from102 to 1,053 units/mL, with the highest activity determined for L. paracasei YSM0308. Optimal conditions for GOS synthesis are as follows: concentration of whey powder, pH, temperature, and time were 30%, pH 6.5-7.0, <TEX>$30^{\circ}C$</TEX>, and 4 h, respectively. The final GOS concentration was 19.41% (w/v) by the crude YSM0308 lactase, which was obtained from strain YSM0308 grown in the 10% (w/v) reconstituted whey-based medium.

Simultaneous Determination of Hydrolysis and Mutarotation Rates during the Enzymatic Hydrolysis of Lactose

An experiment is described in which a custom-made glucose electrode is used to directly monitor the enzymatic hydrolysis of lactose to glucose. The transient profile of beta- d-glucose can be used to simultaneously determine the rate constants for mutarotation and for enzymatic hydrolysis by applying a dynamic nonlinear regression routine. Due to differences in the mutarotation rate constants between lactose and glucose, the beta- d-glucose concentration "overshoots" equilibrium under certain conditions, which can be modeled mathematically. This overshoot can be observed reliably and used to quantify the differences in mutarotational equilibria between glucose and lactose. These observations may be important for the analysis of dairy products and commercial lactase preparations and illustrate an unusual kinetic phenomenon caused by intramolecular forces. This approach may also be important for the accurate determination of a variety of oligosaccharides such as glycogen, which tend to be composed primarily of one stereoisomer.

Marked Production of Ginsenosides Rd, F2, Rg3, and Compound K by Enzymatic Method

The hydrolysis of protopanaxadiol-type saponin mixture by various glycoside hydrolases was examined. Among these enzymes, crude preparations of lactase from Aspergillus oryzae, beta-galactosidase from A. oryzae, and cellulase from Trichoderma viride were found to produce ginsenoside F(2) [3-O-(beta-D-glucopyranosyl)-20-O-beta-D-glucopyranosyl-20(S)-protopanaxadiol], compound K [20-O-beta-D-glucopyranosyl-20(S)-protopanaxadiol], and ginsenoside Rd {3-O-[beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranosyl]-20-O-beta-D-glucopyranosyl-20(S)-protopanaxadiol}, respectively, from protopanaxadiol-type saponin mixture in large quantities. Moreover, the crude preparation of lactase from Penicillium sp. having a high producing activity of ginsenoside Rh(1) (6-O-beta-D-glucopyranosyl-20(S)-protopanaxatriol) from protopanaxatriol-type saponin mixture gave ginsenoside Rd as a main product, ginsenoside Rg(3) {3-O-[beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranosyl]-20(S)-protopanaxadiol}, and compound K from protopanaxadiol-type saponin mixture. The hydrolytic pathways of ginsenosides Rb(1), Rb(2), and Rc to ginsenosides Rd, Rg(3), and F(2), and compound K by crude preparations of four glycoside hydrolases were also studied. This is the first report on the enzymatic preparation of an intestinal bacterial metabolite, ginsenoside F(2), in quantity, and a considerable amount of a minor saponin, ginsenoside Rg(3), from a protopanaxadiol-type saponin mixture.

Effect of lactase preparations in asymptomatic individuals with lactase deficiency--gastric digestion of lactose and breath hydrogen analysis.

We compared two lactase preparations derived from Aspergillus orizae (AOL) and Penicillinase multicolor (PML) for stability in the stomach and overall enzymatic activity in 10 asymptomatic subjects with lactase deficiency. The subjects were given 10,000 FCC units of either AOL or PML 30 min prior to or simultaneously with 300 ml of milk. Gastric juice was withdrawn through a nasogastric tube immediately after and every 15 min for 60 min, and breath was sampled before and every 15 min for 6 h after the milk ingestion. When lactase was given simultaneously with the milk, gastric juice lactase activity and galactose concentration were significantly higher than the control levels. When lactase preparations were given 30 min prior to the milk, neither lactase activity nor galactose was detected in the gastric juice. The pH of the gastric juice was about 6.0 after the milk ingestion. Breath hydrogen did not increase when milk was ingested simultaneously with enzymes, but did increase if enzymes were given 30 min prior to milk ingestion. There were no significant differences in lactase activity, galactose concentration in gastric juice, or breath hydrogen when AOL and PML were compared. In conclusion, with exogenous lactase, digestion of lactose begins in the stomach when pH is raised to 6.0 by the buffering action of milk. Lactase preparations are effective assessed by breath hydrogen analysis in asymptomatic individuals with lactase deficiency if the enzymes are given simultaneously with milk.

Nutritional Supplements Used in Weight-reduction Programs Increase Intestinal Gas in Persons Who Malabsorb Lactose

Objective To determine if ingestion of 2 doses of milk-based dietary supplements produce gaseous symptoms in subjects who malabsorb lactose. Design Randomized, controlled, crossover trial. Subjects/setting Ten community-based subjects who malabsorb lactose. Intervention Ingestion of 2 standard servings of milk-based supplements (a powder reconstituted in fat-free milk or a ready-to-drink preparation) or low-lactose control preparations. Main outcome measures Frequency of flatus passage and subjective impression of bloating, flatulence, and abdominal discomfort. Statistical analysis Wilcoxon signed-rank test. Results The high lactose content (27 g) of 2 servings of the powder-based supplement ingested without other food resulted in a marked increase in daily flatus passages from the basal level of 9.7±8.2 to 30±14 (mean ±SD), and a significant increase in the subjects’ perception of gas. In contrast, the lower lactose content (18.4 g) of 2 servings of a ready-to-drink supplement resulted in a flatus frequency of 17±10 (P=.14 vs baseline) and no significant increase in the perception of increased gas. Neither supplement resulted in a significant increase in bloating, abdominal pain, or diarrhea. The lactose content of the liquid supplement was reduced by 80% following overnight incubation with an over-the-counter lactase preparation. Applications/conclusions Persons who malabsorb lactose should be aware that sizable increases in rectal gas commonly occur when milk-based powders reconstituted in milk are used as meal replacements. In contrast, gas problems probably will be minor following ingestion of 2 doses of a ready-to-drink, milk-based supplement. The lactose content of these supplements can be markedly reduced by overnight incubation with over-the-counter lactase preparations, and this manipulation should be beneficial for subjects troubled by the increased gas caused by the consumption of lactose-containing supplements. J Am Diet Assoc. 2001;101:1447–1452.