The effects of probiotics in lactose intolerance: A systematic review

Over 60 percent of the human population has a reduced ability to digest lactose due to low levels of lactase enzyme activity. Probiotics are live bacteria or yeast that supplements the gastrointestinal flora. Studies have shown that probiotics exhibit various health beneficial properties such as improvement of intestinal health, enhancement of the immune responses, and reduction of serum cholesterol. Accumulating evidence has shown that probiotic bacteria in fermented and unfermented milk products can be used to alleviate the clinical symptoms of lactose intolerance (LI). In this systematic review, the effectiveness of probiotics in the treatment of LI was evaluated using 15 randomized double-blind studies. Eight probiotic strains with the greatest number of proven benefits were studied. Results showed varying degrees of efficacy but an overall positive relationship between probiotics and lactose intolerance.     

Caking characteristics and sensory attributes of ramen soup powder evaluated using a low-resolution proton NMR technique

A low-resolution proton nuclear magnetic resonance (NMR) technique was used to characterize the quality of ramen soup powder during storage. The caking behavior of ramen soup powders was observed during 20 weeks of storage at different temperatures (30, 37, 45, and 55 °C) by monitoring changes in spin-spin relaxation times (T₂) using a CPMG (Carr-Purcell-Meiboom-Gill) pulse sequence. Water in ramen soup powder was classified into two fractions based on two spin-spin relaxation times, T₂₁ and T₂₂, and their respective proton intensities, A₁ and A₂. Increases in T₂₁ and T₂₂ were observed during storage at 37, 45, and 55 °C, which indicated that the molecular mobility of water in ramen soup powder increased. The changes in A₁ and A₂ suggested that there was a redistribution of water from a lesser “bound” water state to more mobile state during storage. T₂₁ and A₁ were critical factors for explaining the caking characteristic of ramen soup powder during storage. Also, the results showed that sensory attributes of ramen soup powder deteriorated during storage, indicating that caking could accompany changes in organoleptic qualities and that these changes could be detected by monitoring changes in NMR parameters.     

Multivariate near-infrared and Raman spectroscopic quantifications of the crystallinity of lactose in whey permeate powder

The use of near-infrared (NIR) and Fourier transform Raman spectroscopy for quantification of crystalline lactose content in whey permeate powder was investigated using chemometric methods. Sample sets consisting of binary mixtures of crystalline (50.0–98.0%) and amorphous lactose and process whey permeate samples with different amounts of crystalline lactose (75.0–95.5%) added were analyzed. The best results for quantification of crystallinity were obtained by partial least squares (PLS) regression on NIR data in five selected intervals in the range 1100–2498 nm. Data analysis on the total sample set of 35 samples yielded a prediction error (root mean square error of cross validation) of 0.627%. The corresponding result for Raman spectroscopy in the range 3500–100 cm⁻¹ was 1.62%. Interval-PLS regression was used for the selection of relevant spectral intervals as well as for improving the spectral interpretation. Alternating regression was used to show that the amorphous lactose preparation contained only a negligible amount of crystalline lactose.     

Prediction of moisture transfer parameters for microwave drying of lactose powder using Bi–G drying correlation

The mass transport properties characterising the drying of lactose powder were determined using a correlation proposed by Dincer and Hussain [Dincer, I. & Hussain, M. M. (2004). Development of a new Bi–Di correlation for solids drying. International Journal of Heat and Mass Transfer, 47, 653–658]. Experimental moisture content data for lactose samples dried under convective, microwave, combined convective-microwave and combined vacuum-microwave conditions were collected. The drying coefficients and lag factors were calculated from the experimental data and incorporated into the model. The Bi numbers were in the range 0.185–439, and moisture diffusivities and diffusion coefficients in the range from 0.135 × 10⁻⁹ to 102 × 10⁻⁹ and from 0.194 × 10⁻⁶ to 118 × 10⁻⁶ m/s, respectively. The predicted moisture profiles showed adequate agreement with the experimental observations, with the average error between experimental and predicted results being ±13.7%.     

Crystallization behavior of lactose/sucrose mixtures during water-induced crystallization

The crystallization behavior of lactose/sucrose mixtures during water-induced crystallization was studied to gain more insight about their crystallization during storage. Solutions with different ratios of lactose and sucrose, 75:25 and 50:50, were spray dried to produce amorphous powders. The powders were kept at a controlled temperature and humidity to study their sorption–desorption behavior. X-ray diffraction and light microscopy analysis were performed to study their crystallization behavior. Two-step desorption was observed after sieving the powders as sample preparation. Sieving decreased the crystallization time for lactose/sucrose mixture 75:25 from 22 days to 2.5 days. Based on the X-ray diffraction analysis during this two-step process of water desorption, it was concluded that lactose crystallizes first and more quickly than sucrose. The degree of crystallization for the lactose crystals increases by 89% (relative to their final level of crystallinity), whereas sucrose crystals increase their level of crystallinity by only 28% during the first step of crystallization in the lactose/sucrose (75:25) mixtures. The light microscopy images also suggested that the crystallization of amorphous lactose/sucrose powders during water-induced crystallization may occur as a solution rather than in the solid phase.     

Effective moisture diffusivity modelling versus food structure and hygroscopicity

Effective moisture diffusivities (D_eff) for model food systems presenting distinct structure and water sensibility were identified at various levels of hydration. Experimental moisture sorption kinetics with a controlled atmosphere microbalance were analyzed using distinct Fickian models with specific assumptions. Taking into account the deformation and the external resistance to mass transfer, higher values of D_eff were identified specially for hygroscopic dense products in the range of high water activity. The difference of impact of the model assumptions on D_eff depending on the investigated water activity range and food material was related to the structure and the equilibrium moisture sorption properties.     

Water sorption and glass transition properties of spray dried lactose hydrolysed skim milk powder

The moisture sorption behaviour and glass transition temperature of spray dried skim milk powder with hydrolysed lactose (SMPHL) were determined. Spray drying of skim milk with hydrolysed lactose resulted in very low cyclone recovery of 25% and a large amount of powder remained stuck inside the spray dryer. The equilibrium moisture content of SMPHL was lower than that of lactose for each range of water activity when humidified for 21 days at 23 °C using saturated salt solutions. Unlike lactose, SMPHL did not lose water when the water activity exceeded 0.432 and no crystallization was noticed at water activity ?0.753. The sorption isotherm data for SMPHL fitted well with the BET and GAB models with monolayer moisture contents of 7.55 and 8.27 g/100 g, respectively. The glass transition temperature of anhydrous SMPHL was 49 °C. The critical water activity and moisture content for SMPHL were 0.15 and 2.4 g/100 g dry solid, respectively. The low critical values indicated hydrolysis of lactose necessities maintenance of very low moisture of powder for its long-term stability.     

Moisture sorption characteristics of curd (Indian yogurt) powder

The moisture sorption behaviour of curd (Indian yogurt) powder was studied at 20, 30, 40 and 50°C for water activity ranging from 0.07 to 0.85. GAB, BET, Henderson, Halsey, Chung & Pfost, Smith, Oswin and Peleg models were applied to analyse the data. Estimated parameters and fitting ability for sorption models were evaluated. The GAB model showed the best fit to the sorption data of curd powder at 20, 30 and 40°C, and the Peleg model fitted well at 50°C.     

Ultrasonic characterization of lactose dissolution

The ultrasonic properties (at 2.25 MHz) of lactose solutions and suspension of lactose crystals (d ∼ 50 μm) were measured as a function of concentration (0–40 wt.%). Ultrasonic velocity increased linearly with concentration regardless of the state of dissolution of the lactose crystals while ultrasonic attenuation was low and concentration-independent when the lactose was dissolved and increased approximately linearly with the concentration of suspended crystals. Therefore the amount of lactose present and the state of dissolution can be determined simultaneously with single ultrasonic sensor. A sensor based on this principle was applied to a stirred tank and used to measure the time taken to mix powdered lactose into a solution and the time for the added lactose to dissolve.     

Lactose recovery from Panela cheese whey: Effect of whey acidification on spontaneous and stirring-induced crystallisation

This work aimed to investigate the kinetics, yield, size and composition changes in lactose crystals when Panela cheese whey was acidified (pH 3.80) or slightly alkalinised (pH 6.89) before being subjected to spontaneous or stirring-induced crystallisation. At pH 3.8, the crystallisation was accelerated, and the incorporation of salts and proteins in lactose crystals decreased. Nevertheless, these conditions induced the formation of amorphous lactose. In contrast, at pH 6.89 and under stirring conditions, the amorphous lactose was not formed and gave a high crystallisation yield (∼25 g of lactose per Kg of whey) with ∼80% of lactose recovery.     

牛乳中乳糖低温水解的研究

主要探讨了鲜牛乳中乳糖的低温水解?试验表明生奶中加入0．15U／kg的乳糖酶，在5℃、水解18h，可使生鲜牛乳中的乳糖降解55％左右，从而可以克服乳糖不耐症的问题。     

A novel enzymatic method for the measurement of lactose in lactose-free products

The cover image is based on the Research Article A novel enzymatic method for the measurement of lactose in lactose-free products by David Mangan et al., DOI: 10.1002/jsfa.9317 . This cover was supported by Megazyme.

     

碳法、亚法糖储存期间色值、酚铁、结块等问题研究

本文从产品质量的角度探讨碳酸法糖（简称碳法糖）、亚硫酸法糖（简称亚法糖）在储存期间的色值、水分变化和结块等情况。通过比较分析,得出了影响白砂糖色值以及导致其结块的主要原因,并提出相应的措施保证储存期内产品的质量。     

Moisture sorption isotherms of nutritious supplementary foods prepared from cereals and legumes for feeding rural mothers and children

 Four types of supplementary foods (FSs) based on popped wheat (Triticum vulgare), ragi (Eleusine coracana), bajra (Pennisetum americanum) and sorghum (Sorghum bicolor) blended with soy (Glycine max Merr) and bengalgram (Cicer arietinum) and fortified with vitamins and minerals were prepared on a pilot plant scale. All the FSs contained 10–20% proteins and 350–380 kcal of energy. Moisture sorption characteristics of these FSs were evaluated at room temperature (27  °C) with a view to designing a functional package for such products. The results revealed that a moisture content of about 10% (equilibrium relative humidity 68–70%) is optimum to give a good storage stability to the products. Above the 10% moisture level the products were found to be vulnerable to microbial spoilage (mould growth), leading to quality deterioration. In order to protect these types of products from being spoiled by mould growth during storage, use of moisture-proof packaging materials based on high density polyethylene and polypropylene may be considered. Received: 13 August 1999     

Egg shell as catalyst of lactose isomerisation to lactulose

A feasible way to produce lactulose, employing milk ultrafiltrate as source of lactose and egg shell as catalyst, is proposed as an alternative means for utilising these industrial wastes. Influences of catalyst loadings, lactose concentration and pH on lactose isomerisation were studied. Optimal production of lactulose was reached at 98 °C, employing 6 mg/ml of catalyst loading within 60 min of reaction. Quantities of lactulose of 1.18 g/100 ml and low levels of secondary products (epi-lactose, galactose and organic acids) were produced under these conditions of reaction. Methodology to remove coloured by-products from lactulose syrup in a range of 65–92% was established.     

Galactosyl-oligosaccharide formation during lactose hydrolysis: A review

Enzymatic hydrolysis of lactose is accompanied by galactosyl transfer to other sugars, thereby producing oligosaccharides. These are hydrolyzed slowly, both in vitro and in vivo. They can be thought of as low molecular weight, non-viscous, water-soluble, dietary fibre. They are considered to be physiologically functional foods which promote the growth of bifidobacteria in the colon and a wide variety of health benefits has been claimed in connection with this effect. This article reviews the mechanism of oligosaccharide formation, and then discusses the amount and nature of the products as well as the factors which influence them. The appearance and disappearance of oligosaccharides is explored through consideration of the kinetics of tranferase activity. The consequences of oligosaccharide formation for dairy processing, food analysis, nutrition and health are then briefly discussed.     

Development of a method for water determination in lactose

The determination of water content of lactose and the water activity, which is related to it, are important to assess its microbiological stability as well as its technical and commercial quality. Lactose is a very important product in the dairy sector, but also in the pharmaceutical domain.     

Skim milk powder supplementation affects lactose utilization, microbial survival and biotransformation of isoflavone glycosides to isoflavone aglycones in soymilk by Lactobacillus

Four probiotic bacteria, Lactobacillus acidophilus 4461, L. acidophilus 4962, Lactobacillus casei 290 and L. casei 2607, were used for fermentation of soymilk (SM) prepared from soy protein isolate (SPI) supplemented with skim milk powder (SMP) (SSM). Soymilk and reconstituted skim milk (RSM) were used as controls. Lactose utilization in SSM by these probiotic organisms ranged from 14.97 to 18.15mg/ml, compared to 14.12-16.06mg/ml for RSM. The pH in SSM dropped to 4.07-4.29 compared to 6.15-6.36 for SM and 4.10-4.96 for RSM. The microbial viable counts were also significantly enhanced by up to 0.98logCFU/ml by the supplementation of SMP to SM. The biotransformation level of isoflavone glycosides (IG) to isoflavone aglycones (IA) in SSM ranged from 81.4% to 85.1%, which was 13.9-19.0% higher than that for SM, after 24h of incubation. Most of IG in SSM was completely converted to IA, except malonyl glycitin and malonyl genistin. At the end of the incubation, IA comprised up to 76.8% of total isoflavones in SSM.     

Glass transition and caking of spray-dried lactose

Simple test methods to determine the onset temperatures of viscous flow and caking of spray-dried amorphous lactose are described. The extent of viscous flow was measured as an increase in the density of lactose plugs within a cylindrical aluminium compaction apparatus after incubation for 3h at a specified temperature. Caking was characterized by an increase in the hardness of the lactose plugs formed. The onset temperature of viscous flow decreased with increasing water activity, A_w, and corresponded to the onset temperature of glass transition, T_g1. Glass transition temperatures were determined using both differential scanning calorimetry (DSC) and nuclear magnetic resonance (NMR) spin relaxation. The results suggest that elevation of the powder temperature above T_g1 promotes viscous flow and increases the potential for caking of amorphous food powders.     

The effect of chitosan hydrogen bonding on lactose crystallinity during spray drying

The effect of chitosan on the crystallization behavior of lactose has been studied during the spray drying of lactose/chitosan solutions. Solutions with different ratios of lactose and chitosan have been spray dried at an inlet temperature of 160 °C using a laboratory-scale spray dryer. Water-induced crystallization, X-ray diffraction analysis and differential scanning calorimetry have been used to study the crystallinity of the spray-dried lactose/chitosan powders. Results show that, despite the ability of chitosan to retain moisture for a longer time during spray drying, the spray-dried powders were in the amorphous form. Moisture-induced crystallization and differential scanning calorimetry results suggest that the presence of chitosan delays lactose crystallization. This finding may be due to the high glass-transition temperature of chitosan, despite its ability to hydrogen bond with water, which was suggested previously by other researchers to be a reason for crystallizing lactose during spray drying in the presence of polyethylene glycol.