Low Lactose Content Research Articles

Preparation of an inexpensive milk with high calcium and low lactose content

Preparation of an inexpensive milk with high calcium and low lactose content

SPECTROPHOTOMETRIC DETERMINATION OF WPNI AND HMF IN UHT MILK THROUGH THE PRINCIPAL COMPONENTS ANALYSIS

During heat milk suffers changes among which whey proteins insolubility and Maillard reaction can be monitored using spectrophotometric methods by determining the whey protein nitrogen (WPNI) and 5-hydroxymethylfurfural (HMF). The aim of this work was the evaluation of heat in commercial UHT milk samples through HMF and WPNI determination by spectrophotometric methods in visible region, using chemometric tools in data analysis. The regression models were fitted and statistical assumptions were tested. The WPNI confidence interval (CI) was (0.91; 3.73) mg mL-1 showing the heat severity and classifying the samples as medium heat treatment according to American Dairy Products Association. For free HMF index, the CI were: (2.39; 3.27) and (6.01; 6.89) µmol L-1 for regular and low lactose content samples, respectively; while these two samples group presented CI of (11.67; 12.39) and (132.28; 143.22) µmol L-1 for total HMF index, respectively; showing the influence of lactose content in total HMF index. Descriptive statistical analysis associated with principal component analysis demonstrated a lack of standardization in the current Brazilian UHT process. The spectrophotometric methods allowed obtaining further inferences about the product quality associated to its heat treatment.

Effects of Environmental Factors on Soluble Expression of a Humanized Anti-TNF-α scFv Antibody in Escherichia coli

The bacterial cultivation conditions for obtaining anti-TNF-α single chain variable fragment (scFv) antibody as the soluble product in E. coli was investigated. To avoid the production of inclusion bodies, the effects of lactose, IPTG, incubation time, temperature, shaking protocol, medium additives (Mg+2, sucrose), pH, osmotic and heat shocks were examined. Samples from bacterial growth conditions with promising results of soluble expression of GST-hD2 scFv were affinity purified and quantified by SDS-PAGE and image processing for further evaluation. The results showed that cultivation in LB medium under induction by low concentrations of lactose and incubation at 10 °C led to partial solubilization of the expressed anti-TNF-α scFv (GST-hD2). Other variables which showed promising increase in soluble expression of GST-hD2 were osmotic shock and addition of magnesium chloride. Furthermore, addition of sucrose to medium suppressed the expression of scFv completely. The other finding was that the addition of sorbitol decreased the growth rate of bacteria. It can be concluded that low cultivation temperature in the presence of low amount of inducer under a long incubation time or addition of magnesium chloride are the most effective environmental factors studied for obtaining the maximum solubilization of GST-hD2 recombinant protein.

FT-Raman and chemometric tools for rapid determination of quality parameters in milk powder: Classification of samples for the presence of lactose and fraud detection by addition of maltodextrin

FT-Raman spectroscopy has been explored as a quick screening method to evaluate the presence of lactose and identify milk powder samples adulterated with maltodextrin (2.5–50% w/w). Raman measurements can easily differentiate samples of milk powder, without the need for sample preparation, while traditional quality control methods, including high performance liquid chromatography, are cumbersome and slow. FT-Raman spectra were obtained from samples of whole lactose and low-lactose milk powder, both without and with addition of maltodextrin. Differences were observed between the spectra involved in identifying samples with low lactose content, as well as adulterated samples. Exploratory data analysis using Raman spectroscopy and multivariate analysis was also developed to classify samples with PCA and PLS-DA. The PLS-DA models obtained allowed to correctly classify all samples. These results demonstrate the utility of FT-Raman spectroscopy in combination with chemometrics to infer about the quality of milk powder.

Characterization of nutritional parameters in bovine milk by Raman spectroscopy with least squares modeling

ABSTRACTThe macronutrient constitution of bovine milk was investigated by Raman spectroscopy involving 830 nm excitation at 300 mW from 600–1800 cm−1 with a probe. Bovine milk was analyzed for total proteins, casein, total fat, and lactose by standard assays. The concentrations of these components were estimated by correlating these assays with the fitting coefficients based on least-squares fitting of lactose, casein, triolein, and stearic acid and milk spectra to prepare calibration curves. The model was employed for the analysis of milk from local markets. The spectra of milk were dominated by bands of proteins, lipids, and carbohydrates. There was a strong correlation between the concentrations of total proteins and casein (r = 0.75 and 0.73, respectively), and very strong correlation for total fat and lactose (r = 0.93 and 0.91, respectively) with the standard errors of prediction of 0.49, 0.38, 0.61, and 0.27 mg/dL, respectively. The milk contained lower concentrations of lactose and protein than in the nutritional facts table. The amount of saturated fat was close to the nutritional value with more unsaturated fat. A single Raman spectrum was employed to characterize the composition of milk and may have application for rapid quality control.

Effect of adding soymilk on physicochemical, microbial, and sensory characteristics of probiotic fermented milk containing Lactobacillus acidophilus

Summary The aim of the present study was to investigate the effect of addition of soymilk on physicochemical, microbial, and sensory characteristics of milk fermented with Lactobacillus acidophilus. Soybeans were blended 1:5 w/v with distilled water. The prepared soymilk was added to milk in combinations of 20%, 40%, and 60%. Milk was used as the control. All the samples were sterilized and fermented with Lactobacillus acidophilus LA-5 as probiotics. Then, they were kept at 5oC for 14 days. Microbial count, titratable acidity, pH, syneresis, color parameters and sensory evaluation were performed during the storage time. Results showed that all the samples possessed minimum effective dose of LA-5 on day 14, although a significant decrease in LA-5 was observed in the sample with 60% soymilk. In each experimental day, there was a noticeable decrease in the pH of the samples. Addition of soymilk to milk also significantly increased syneresis, particularly in samples with 60% soymilk. Sensory evaluations showed that scores of texture, mouth sense, aroma, and flavor of the samples with 40% and 60% soymilk were significantly lower than other samples. With respect to color, “L” value decreased significantly in the fermented product with 60% soymilk and the decrease was more pronounced with longer storage times. In conclusion, addition of 20% soymilk did not substantially alter physicochemical and sensory characteristics of milk while providing an appropriate growth culture for LA-5. The mixture of milk-20% soymilk can be introduced as a good probiotic product with lower lactose content and additional nutritional benefits.

Understanding the role of natural cheese calcium and phosphorous content, residual lactose and salt‐in‐moisture content on block‐type processed cheese functional properties: Cheese hardness and flowability/meltability

Four treatments of natural Cheddar cheese with two levels (high and low) of calcium (Ca) and phosphorus (P), and two levels (high and low) of residual lactose were manufactured. Each treatment was subsequently split prior to the salting step of cheese manufacturing processed and salted at two levels (high and low) for a total of eight treatments. The eight treatments included: high Ca and P, high lactose, high salt‐in‐moisture (S/M) content (HHH); high Ca and P, high lactose, low S/M (HHL); high Ca and P, low lactose, high S/M (HLH); high Ca and P, low lactose, low S/M (HLL); low Ca and P, high lactose, high S/M (LHH); low Ca and P, high lactose, low S/M (LHL); low Ca and P, low lactose, high S/M (LLH); and low Ca and P, low lactose, low S/M (LLL). After 2 months of ripening, each treatment of natural Cheddar cheese was used to manufacture processed cheese using a twin‐screw Blentech processed cheese cooker. All of the processed cheese food formulations were balanced for moisture, fat and salt. Texture and melt‐flow characteristics of the processed cheese were evaluated with different techniques, including texture profile analysis (TPA) for hardness and melt profile analysis. There was a considerable increase in cheese hardness for the processed cheeses prepared from high Ca and P content, and high S/M natural cheeses compared with low Ca and P content and low S/M natural cheeses. Moreover, definite decrease in flow rate and extent of flow was observed for processed cheeses manufactured from high Ca and P content, and high S/M natural cheeses than that of low Ca and P content and low S/M natural cheeses. No considerable trend was observed in hardness and melt‐flow characteristics for the processed cheeses manufactured from high and low residual lactose content natural Cheddar cheeses. This study strongly demonstrates that the characteristics of natural cheese (calcium and phosphorus content, lactose content and salt‐in‐moisture content) used in processed cheese manufacture have a significant impact on processed cheese functionality.

VZTAH KONCENTRACE ZDRAVOTNĚ VÝZNAMNÝCH SKUPIN MASTNÝCH KYSELIN KE SLOŽKÁM A TECHNOLOGICKÝM VLASTNOSTEM KRAVSKÉHO MLÉKA

Groups of fatty acids (FAs) in milk fat can have positive and negative impact on consumer health. Profile of FAs could be influenced by dairy cow nutrition, breed, milk yield level et cetera. The question is what relationships the FAs could have to quality of milk products? Relationships between FAs and their groups to selected milk indicators were studied in Czech Fleckvieh and Holstein cows (64 bulk milk samples). There were 8 herds in 2-year investigation during winter and summer season. The relationship of saturated FAs (SAFA; 66.22%) was significant only to lactose (L) content (0.290; P < 0.05). The relationships of monounsaturated FAs (MUFA; 29.21%) to milk indicators (MIs) were in­si­gni­fi­cant (P > 0.05). The relationships of polyunsaturated FAs (PUFA, beneficial for consumer health; 4.53%) to MIs were narrower: fat (T, 0.321; P < 0.05); lactose (L, 0.458; P < 0.01); milk alcohol stability (AL, 0.447; P < 0.01); titration acidity (SH, 0.342; P < 0.01); cheese curd quality (KV, 0.427; P < 0.01); milk fermentationability (JSH, 0.529; P < 0.001), streptococci count in yoghurt (Strepto, 0.316; P < 0.05); total count of noble bacteria in yoghurt (CPMUK, 0.314; P < 0.05); streptococci/lactobacilly ratio (StreptoLacto, 0.356; P < 0.01). The relationships of conjugated linoleic acid (CLA; markedly beneficial for health; 0.68%) to MIs were: T (0.379; P < 0.01); L (–0.542; P < 0.001); AL (0.266; P < 0.05); KV (0.411; P < 0.01); Strepto (0.260; P < 0.05); StreptoLacto (0.270; P < 0.05). The higher CLA levels were connected in this way with: higher fat content; lower lactose content; lower alcohol stability; lower streptococci count in yoghurt; lower streptococci/lactobacilly ratio in yoghurt. The PUFA and CLA representation decreased with L increase. Simultaneously some technological milk properties such as alcohol sta­bi­li­ty and fermentationability were slightly improved.

Milk quality, coagulation properties, and curd firmness modeling of purebred Holsteins and first- and second-generation crossbred cows from Swedish Red, Montbéliarde, and Brown Swiss bulls

The objective of the present study was to investigate how the crossbreeding of Holstein (HO) cows with bulls from Nordic and Alpine European breeds affect milk quality traits, traditional milk coagulation properties (MCP), and curd firmness modeling obtained from individual milk samples. A total of 506 individual milk samples were collected from evening milking at 3 commercial farms located in Northern Italy. Over the past decade, the 3 farms have followed crossbreeding programs in part of their herds, whereas the remainder of the animals consisted of purebred HO. The basic scheme was a 3-breed rotation based on the use of Swedish Red (SR) semen on HO cows (SR × HO), the use of Montbéliarde (MO) semen on first-cross cows [MO × (SR × HO)], and the use of HO semen in the third cross. In all herds, a smaller proportion of purebred HO were mated to M and Brown Swiss (BS) bulls, and these first crosses were mated to SR and MO bulls, respectively. Milk samples were analyzed for milk composition and MCP, and parameters for curd firmness were modeled. Compared with purebred HO, crossbred cows produced less milk with lower lactose content, higher fat and protein content, and a tendency for higher casein content. Crossbred cows generally produced milk with a more favorable curd-firming rate (k20) and curd firmness 30min after rennet addition, among traditional MCP, and better trends of curd firmness measures as shown by model parameters: estimated rennet coagulation time, asymptotical potential value of curd firmness, and curd-firming instant rate constant. Among crossbred cows, SR × HO presented longer rennet coagulation time compared with MO × HO and BS × HO cows, and MO × HO showed shorter k20 compared with BS × HO cows. Among second-generation cows, those sired by SR bulls showed a lower incidence of noncoagulated samples, higher curd firmness 30min after rennet addition and asymptotical potential value of curd firmness, and faster curd-firming instant rate constant compared with animals sired by MO bulls. Our results revealed that different sire breeds were characterized by specific technological aptitudes, but that these were not strictly related to other milk quality traits. Furthermore, the favorable characteristics (in terms of the quality and technological properties of milk) could be maintained in the third generation of 3-way crosses without negative effects on milk yield, even though the HO heritage had been reduced from 50 to 25%. Our findings, therefore, suggest that different types of sires can be chosen (depending on the intended use of the milk) to ensure the optimization of farm crossbreeding programs.

Influence of autochthonous lactic acid bacteria and enzymatic yeast extracts on the microbiological, biochemical and sensorial properties of Lben generic products

In this study we identified Lactococcus lactis subsp. lactis, Lc. lactis subsp. lactis biovar diacetylactis, Kluyveromices lactis and Saccharomyces cerevisiae as the dominant microorganisms of traditional Moroccan acid-alcoholic fermented milk named Lben. The low pH (3·8±0·3), lactose (16·8±3·4mg/l) and lactic acid (8·16±0·6mg/l) content indicated that a strong fermentation occurred in the traditional product which was also characterised by the substantial presence of ethanol and typical volatile carbonyl compounds (i.e., acetoin, diacetyl and acetaldehyde). Microbiological analyses of experimental Lben manufactured with selected strains (isolated from the traditional product) of Lc. lactis subsp. lactis and Lc. lactis subsp. lactis biovar. diacetylactis alone (batch A) and in combination with enzymatic extract of a K. lactis strain (batch B) indicated a good effectiveness of the starters employed (∼1010 CFU/g of lactococci after 8h of incubation) and a significant effect of the yeast enzyme extract on lactococci viability. Despite slight changes in the physicochemical characteristics of the two Lben during the 15d storage period, volatile compounds (i.e. ethanol, acetaldehyde, diacetyl and acetoin) were consistently higher in batch B. Moreover, sensorial analysis performed after 15d of storage, highlighted higher odour and flavour intensity, vegetable odour and viscosity in batch B while batch A displayed higher astringency.

Consumption of raw or heated milk from different species: An evaluation of the nutritional and potential health benefits

Abstract Based on literature data, the composition of milk from different ruminants (cow, sheep, goat, buffalo, camel, llama, yak and deer) and equidae (horse and donkey) and of human milk were compared to examine possible nutritional differences. Additionally, the alleged health benefits attributed to some of these milks and the effect of heating are discussed. Very generally, ruminant milk has a lower lactose content, but a higher protein (and casein), fat (with a higher share of saturated and mono-unsaturated fatty acids and a higher cholesterol level), vitamin (except for vitamin C) and mineral content compared to horse or donkey milk. Milk composition may however vary largely, not only between ruminants and non-ruminants, but also between different breeding variants of the same species and between individual animals. Consequently, a constant health promoting potential is, if present, difficult to guarantee. Moreover, differences in milk composition do not only concern the relative proportions of the milk components, but also occur at the molecular level (e.g. monomeric versus dimeric proteins, different amino acid sequence). Pasteurization is not expected to affect the nutritional (or presumed health) benefits significantly, regardless of differences observed in thermostability between components of considered types of milk. Even though the milk composition of some animal species resembles to a great extent the composition of human milk, it is recommended to give either human milk or formula milk to babies and infants. For people suffering from milk allergy, milk other than e.g. bovine milk may offer a solution, but this greatly depends from one person to another.

Neuronal and grey modelling of milk drying in spouted bed

AbstractThe chemical composition of pastes is one of the factors responsible for the behaviour of the paste during the drying process in spouted bed. Therefore, the aim of this study was to analyse the drying process of paste in spouted bed for four types of milk: whole, skimmed, semi‐skimmed and low lactose content milk, which have different concentrations of sugar and fat. A neuronal model was proposed in order to describe the influence of the presence of pastes on the spouted bed fluid dynamics. The change of moisture content of the powder during the drying process and of the heat and mass transfer phenomena were estimated using a hybrid model based on the global balance of mass and energy and a phase‐coupling term given by a neural network.

Influence of inulin on chemical, sensorial and survival of L. Acidophilus in symbiotic frozen yogurt with reduced-lactose:

<p>Recently, the dairy industry has given special attention to development of products containing low lactose content, to meet the needs of consumers intolerant to this sugar type. This study aimed to evaluate the effects of adding inulin on chemical, sensory and survival of probiotics in symbiotic frozen yogurt with reduced lactose content during the storage period. The hydrolysis degree achieved using 0.8 g of lactase per liter milk was about 97.54%, being below the limit quantification (0.5%) and being considered as a food for special purposes. Based on the results obtained, it can be concluded that the enzyme lactase effectively reduced the lactose content in frozen developed, not by changing the physicochemical and viability of probiotic culture. The addition of inulin caused a significant change (p<0.05) in sensory attributes evaluated and promoted the growth of <em>L. acidophilus</em>, showing that this type of edible ice cream is a good option for the dairy market, catering lactose intolerant consumers.</p><p> </p><p>DOI: http://dx.doi.org/10.14685/rebrapa.v3i1.90</p>

Simultaneous enzymatic hydrolysis and lactic fermentation to obtain a yogurt with low lactose content

In a single-stage process with the simultaneous addition of β-galactosidase and lactic culture, the lactose conversion, the processing time, viscosity and syneresis were evaluated. Fermentation was promoted by lactic culture containing two probiotic microorganisms, Bifidobacterium animalis and Lactobacillus acidophilus, associated with the typical microorganisms of yogurt. An enzymatic preparation containing β-galactosidases from Kluyveromyces lactis and Aspergillus niger was used. A central composite design (2³ trials plus three central points) was proposed in order to evaluate the effects of initial lactose concentration, enzyme concentration and the time of addition of the enzyme. The following conditions were established: initial lactose concentration of 91 g L-1, enzyme concentration of 0.5 g L-1 and enzyme addition at the beginning of fermentation. In these conditions, a decrease in processing time (from 4.55 to 3.68 h) and an increase in lactose conversion (from 15.2 to 97.9%) were observed in relation to the fermentation without enzyme addition, and no detrimental changes in some physical properties of yogurt (viscosity, and syneresis).

Optimization and shelf life of a low-lactose yogurt with Lactobacillus rhamnosus HN001

Lactose intolerance results in gastrointestinal discomfort and the malabsorption of certain nutrients, such as calcium. The replacement of milk with low-lactose and probiotic-enriched dairy products is an effective strategy of mitigating the symptoms of lactose intolerance. Lactobacillus rhamnosus HN001 (HN001) is a safe, immunity-stimulating probiotic. We have developed a process to increase the hydrolysis of lactose and HN001 growth in yogurt versus β-galactosidase (βG) concentration and enzymatic hydrolysis time (EHT) before bacterial fermentation. The objective of this study was to optimize the conditions by which yogurt is processed as a function of βG and EHT using a multifactorial design, with lactose content, HN001 growth, process time, and sensory quality as dependent variables. Further, the shelf life of the optimized yogurt was evaluated. In the optimization study, polynomials explained the dependent variables. Based on Pearson correlation coefficients, HN001 growth correlated positively with the hydrolysis of lactose. However, low lactose content and high HN001 count increased the fermentation time and lowered the sensory quality. The optimized conditions—using polynomials to obtain yogurt with >1×107 cfu of HN001/mL, <10g of lactose/L, and a minimum overall sensory quality of 7 on the Karlsruhe scale—yielded a theoretical value of 910 neutral lactose units/kg for βG and 2.3h for EHT, which were validated in an industrial-scale assay. Based on a shelf-life study at 3 temperatures, the hydrolysis of lactose and the growth of HN001 continue during storage. Arrhenius equations were developed for the variables in the shelf-life study. Our results demonstrate that it is feasible to develop a low-lactose yogurt to which HN001 has been added for lactose-intolerant persons who wish to strengthen their immune system.

Nitrogen partitioning and isotopic fractionation in dairy cows consuming diets based on a range of contrasting forages

Nine multiparous Holstein-Friesian cows (initially 97 d in milk), were used in a 3×3 lattice square design experiment with 4-wk periods. All cows received 4kg/d concentrates and dietary treatments were based on silages offered ad libitum: perennial ryegrass (PRG); timothy (TIM); tall fescue (TF); red clover (RC); red clover/corn silage mixture [40/60 on a dry matter (DM) basis; RCC]; red clover/whole-crop oat silage mixture (40/60 on a DM basis; RCO); or red clover/whole-crop oat silage mixture (25/75 on a DM basis; ORC). The remaining treatments were based on RCO with feed intake restricted to the level of PRG (RCOr) or with a low protein concentrate (50/50 mixture of barley and molassed sugar beet pulp; RCOlp). Experiment objectives were to evaluate diet effects on N partitioning and N isotopic fractionation. Yields of milk and milk protein were consistently high for diets RC, RCC, and RCO and low for the diets based on poorly ensiled grass silages. Restriction of intake (RCOr) and inclusion of a higher proportion of whole-crop oat silage (ORC) and the low-protein concentrate (RCOlp) led to some loss of production. Diet had little effect on milk fat, protein, and lactose concentrations: low concentrations of milk protein and lactose reflect the restricted energy intakes for all treatments. The highest diet digestibilities were measured for RC and PRG, whereas increasing inclusion of the whole-crop oat silage (0, 60, and 75% of forage DM) led to a marked decrease in diet digestibility (0.717, 0.624, and 0.574g/g, respectively). Urinary excretion of purine derivatives, an indicator for rumen microbial protein synthesis, was significantly higher for RCC than for TIM and TF. Nitrogen intake ranged between 359 and 626g/d (treatment means). Partitioning of N intake to feces and urine was closely related to N intake, although urinary N losses were less than predicted from N intake for the 60/40 mixtures of cereal silage and red clover silage. The 15N content of milk, urine, and feces were all influenced by diet 15N content. Isotopic fractionation meant that feces and milk were enriched and urine was depleted in 15N relative to the diet. Significant relationships were observed between the extent of enrichment of urine, feces, and milk, suggesting some commonality in fractionation pathways. The trend for the lowest 15N enrichment in milk protein occurring in diets with low N-use efficiency (milk N/feed N) was contrary to expectations, possibly because of endogenous contributions to milk protein or fractionation when dietary ammonia was incorporated into microbial protein.

Short communication: Relationships between α-lactalbumin and quality traits in bulk milk

The main objective of this study was to investigate whether the α-lactalbumin (α-LA) content of bulk milk is related with some known inflammatory markers and milk quality traits. An additional objective was to study whether combining α-LA, haptoglobin (Hp), and serum amyloid A (SAA) in an acute phase index (API) could be useful as an alternative marker for bulk milk quality. For the dairy industry, it is of great importance to receive high quality bulk milk for manufacture of liquid milk and dairy products. The somatic cell count (SCC) is currently used as an indirect marker for bulk milk quality, but because it is somewhat insensitive and unspecific, interest exists in alternative markers. Bulk milk samples were analyzed for α-LA, SCC, polymorphonuclear leukocyte count, Hp, SAA, fat, lactose, total protein and casein contents, casein number, protein composition, proteolysis, and coagulating properties. No significant differences were found in SCC, polymorphonuclear leukocyte count, Hp, or SAA between milk samples containing low, medium, or high concentrations of α-LA. Differences between α-LA groups were, however, found in some milk quality traits because high α-LA concentration was related to low concentrations of αS1-, αS2-, and β-caseins and high concentrations of lactose and β-lactoglobulin. A high API was related to low lactose content and casein number. Samples with high SCC contained less casein and had a lower casein number than milk with a low SCC, and proteolysis was significantly higher in high SCC milk than in low SCC milk. Neither α-LA nor API proved to be a better marker than SCC for the quality traits investigated, and α-LA was not considered to be a useful inflammatory marker in bulk milk.

Bioenergy II: An Assessment of the Kinetics of Butanol Production by Clostridium acetobutylicum

Results of a research activity aiming at investigating the feasibility of the acetone-butanol-ethanol (ABE) production by Clostridium acetobutylicum ATCC824 are reported. The kinetics of the ABE production process by free C. acetobutylicum in batch reactors has been assessed. A CSTR equipped with a microfiltration unit has been set-up and operated to assess the kinetics in the solventogenic phase. Solutions of lactose—concentration ranging between 10 and 100 g/L—were adopted as medium with the aim of emulating cheese whey. The conversion process was characterized in terms of cells, acids, solvents, pH and total organic compounds as a function of time. Tests carried out under batch conditions show that: i) cells growth is constant for lactose concentration (CL) smaller than 100 g/L; ii) the butanol specific production rate - estimated at the onset of the solventogenic phase - as a function of CL may be represented by a Monod-like kinetics; iii) the lactose conversion—measured at the end of the solventogenesis phase—decreases with CL; iv) the selectivity of butanol with respect to total solvents increases with CL and stabilizes at about 72%W for CL larger than 30 g/L. Preliminary tests carried out under continuous conditions show that the process takes advantage from the steady state operation under solventogenic conditions. In particular, the butanol conversion rate is larger in the CSTR than in the STR, despite the lower final lactose concentration experienced in the CSTR.

Oxidative stability and quality of raw Saanen and Alpine goats milk

Abstract. The milk composition and concentration of thiobarbituric acid reactive substances (TBARS) and superoxide dismutase (SOD) activity in fresh and refrigerated raw goat milk of Saanen and Alpine breed at the breeding period were investigated. Low average milk fat, SNF and lactose content were determined in both breeds with no significant differences between breeds regarding the milk yield and milk composition. The significantly higher somatic cell count (SCC) was detected in Saanen goats. The SOD activity and TBARS concentration were significantly higher 14 h after the collection and cold storage in both breeds of dairy goats with no difference between the breeds. In the Alpine goats the TBARS concentration was negatively correlated with urea concentration, and in the milk of the Saanen goats the TBARS was positively correlated with proteins and SCC. The higher SCC in the Saanen goats may have caused higher production of secondary oxidative products catalysed by the enzyme superoxide dismutase from polymorphonuclear granulocytes present in the udder, or by some other enzymes that participate in oxidation of the milk constituents. The energy shortage and protein surplus in the diet of the dairy goats may have induced the higher degree of lipid mobilisation and a consequent increase of polyunsaturated fatty acids (PUFA) that are easily prone to oxidation and formation of the secondary oxidative products.

Effect of Calcium and Phosphorus, Residual Lactose, and Salt‐to‐Moisture Ratio on the Melting Characteristics and Hardness of Cheddar Cheese during Ripening

Meltability, melt profile parameters, and hardness of cheddar cheese prepared with varying levels of calcium (Ca) and phosphorus (P) content, residual lactose content, and salt-to-moisture ratio were studied at 0, 1, 2, 4, 6, and 8 mo of ripening. Meltability, melt profile parameters, and hardness of cheddar cheeses measured at 0, 1, 2, 4, 6, and 8 mo of ripening showed significant interaction between the levels of Ca and P, residual lactose, salt-to-moisture ratio, and ripening time for most of the properties studied. cheddar cheese prepared with high Ca and P (0.67% Ca and 0.53% P) resulted in up to 6.2%, 4.5%, 9.6%, 5.0%, and 22.8% increase in softening time, softening temperature, melting time, melting temperature, and hardness, respectively, and 23.5%, 9.6%, and 3.2% decrease in meltability, flow rate, and extent of flow, respectively, compared to the cheddar cheese prepared with low Ca and P (0.53% Ca and 0.39% P). cheddar cheese prepared with high lactose (1.4%) content resulted in up to 7.7%, 7.0%, 4.9%, 4.2%, and 24.6% increase in softening time, softening temperature, melting time, melting temperature, and hardness, respectively, and 14.7%, 12.7%, and 2.8% decrease in meltability, flow rate, and extent of flow respectively compared to the cheddar cheese prepared with low lactose (0.78%) content. cheddar cheese prepared with high salt-to-moisture ratio (6.4%) resulted in up to 21.8%, 11.3%, 12.9%, 4.1%, and 29.4% increase in softening time, softening temperature, melting time, melting temperature, and hardness, respectively, and 13.2%, 28.6%, and 2.6% decrease in meltability, flow rate, and extent of flow, respectively, compared to the cheddar cheese prepared with low salt-to-moisture ratio (4.8%) during ripening.