Exploring Dry-Film FTIR Spectroscopy to Characterize Milk Composition and Subclinical Ketosis throughout a Cow's Lactation.

The use of technologies for measurements of health parameters of individual cows may ensure early detection of diseases and maximization of individual cow and herd potential. In the present study, dry-film Fourier transform infrared spectroscopy (FTIR) was evaluated for the purpose of detecting and quantifying milk components during cows' lactation. This was done in order to investigate if these systematic changes can be used to identify cows experiencing subclinical ketosis. The data included 2329 milk samples from 61 Norwegian Red dairy cows collected during the first 100 days in milk (DIM). The resulting FTIR spectra were used for explorative analyses of the milk composition. Principal component analysis (PCA) was used to search for systematic changes in the milk during the lactation. Partial least squares regression (PLSR) was used to predict the fatty acid (FA) composition of all milk samples and the models obtained were used to evaluate systematic changes in the predicted FA composition during the lactation. The results reveal that systematic changes related to both gross milk composition and fatty acid features can be seen throughout lactation. Differences in the predicted FA composition between cows with subclinical ketosis and normal cows, in particular C14:0 and C18:1cis9, showed that dietary energy deficits may be detected by deviations in distinct fatty acid features.

Manufacture and characterization of acid-coagulated fresh cheese made from casein concentrates obtained by acid diafiltration.

This study aimed to investigate the production of acid-coagulated fresh cheese by using slightly acid diafiltered (DF) microfiltered (MF) casein concentrates (8% protein). Three different acidifying agents were tested during DF: carbon dioxide, lactic acid, and citric acid. Fresh cheese was manufactured using acid-DF casein concentrates, or casein concentrates DF with just water, and compared with cheese manufactured using MF casein concentrates without DF. The fresh cheeses were characterized for composition, rheological, and sensorial properties. Acid-DF casein concentrates improved acidification kinetics during cheesemaking and reduced casein leakage to cheese whey, compared with cheese from regular MF casein concentrate. Among the rheological properties investigated in this study, the storage modulus of the fresh cheese was higher when DF of the casein concentrate was performed with nonacidified DF water or when DF water was acidified with citric acid. However, fresh cheese made from casein concentrate diafiltered with DF water acidified by citric acid was most liked in a sensory ranking test.

Minor acidification of diafiltration water using various acidification agents affects the composition and rennet coagulation properties of the resulting microfiltration casein concentrate.

Cheese made from microfiltration (MF) retentate may suffer from textural defects due to a high Ca concentration. The reduction of colloidal minerals by the acidification of milk before MF at pH below 6.0 has been well documented in the literature. This process, however, creates less valuable side streams to the MF process and induces changes in the casein micelles that negatively affect their coagulation properties. The objective of this study was to determine whether a minor reduction in pH by using different acidifiers in the diafiltration (DF) water could induce changes in composition and renneting properties of the MF retentate. A 2-stage filtration process was used, with the first designed to increase the casein concentration to 8% and the second to slightly reduce the casein concentrate by 0.1 pH unit by DF, without influencing the total protein concentration. Four acidifying agents were tested during DF: lactic acid, hydrochloric acid, citric acid, and carbon dioxide. Diafiltration with water was used as a reference. At the start of DF, the retentates of acid DF had a slightly reduced pH, with an average of 0.09, whereas the pH of the reference retentate increased by an average of 0.07 unit. The reference retentate regained its starting pH by the end of DF. The carbonated retentate gradually increased in pH during processing, whereas the pH of the lactic, hydrochloric, and citric acid retentates remained constant. The permeate from the lactic acid and carbonated treatments had a reduced whey protein content compared with the reference. The total P and inorganic phosphate were lowered in the retentate by using carbonation. The total amount of Mg and Na were lowered in the retentate by using citric acid. The ionic Ca content in the retentate increased with use of lactic or hydrochloric acid. The type of acidifier used reduced the rennet clotting time. Combined acidified diafiltration with a slight reduction affects the permeate composition and improves the retentate clotting time despite the minimal mineral modification.

Microbial Dynamics in Traditional and Modern Sour Beer Production.

Traditional sour beers are produced by spontaneous fermentations involving numerous yeast and bacterial species. One of the traits that separates sour beers from ales and lagers is the high concentration of organic acids such as lactic acid and acetic acid, which results in reduced pH and increased acidic taste. Several challenges complicate the production of sour beers through traditional methods. These include poor process control, lack of consistency in product quality, and lengthy fermentation times. This review summarizes the methods for traditional sour beer production with a focus on the use of lactobacilli to generate this beverage. In addition, the review describes the use of selected pure cultures of microorganisms with desirable properties in conjunction with careful application of processing steps. Together, this facilitates the production of sour beer with a higher level of process control and more rapid fermentation compared to traditional methods.

Co-fermentation Involving Saccharomyces cerevisiae and Lactobacillus Species Tolerant to Brewing-Related Stress Factors for Controlled and Rapid Production of Sour Beer.

Increasing popularity of sour beer urges the development of novel solutions for controlled fermentations both for fast acidification and consistency in product flavor and quality. One possible approach is the use of Saccharomyces cerevisiae in co-fermentation with Lactobacillus species, which produce lactic acid as a major end-product of carbohydrate catabolism. The ability of lactobacilli to ferment beer is determined by their capacity to sustain brewing-related stresses, including hop iso-α acids, low pH and ethanol. Here, we evaluated the tolerance of Lactobacillus brevis BSO464 and Lactobacillus buchneri CD034 to beer conditions and different fermentation strategies as well as their use in the brewing process in mixed fermentation with a brewer's yeast, S. cerevisiae US-05. Results were compared with those obtained with a commercial Lactobacillus plantarum (WildBrewTM Sour Pitch), a strain commonly used for kettle souring. In pure cultures, the three strains showed varying susceptibility to stresses, with L. brevis being the most resistant and L. plantarum displaying the lowest stress tolerance. When in co-fermentation with S. cerevisiae, both L. plantarum and L. brevis were able to generate sour beer in as little as 21 days, and their presence positively influenced the composition of flavor-active compounds. Both sour beers were sensorially different from each other and from a reference beer fermented by S. cerevisiae alone. While the beer produced with L. plantarum had an increased intensity in fruity odor and dried fruit odor, the L. brevis beer had a higher total flavor intensity, acidic taste and astringency. Remarkably, the beer generated with L. brevis was perceived as comparable to a commercial sour beer in multiple sensory attributes. Taken together, this study demonstrates the feasibility of using L. brevis BSO464 and L. plantarum in co-fermentation with S. cerevisiae for controlled sour beer production with shortened production time.

Secondary Lactic Acid Bacteria Fermentation with Wood-Derived Xylooligosaccharides as a Tool To Expedite Sour Beer Production.

Xylooligosaccharides (XOS) from woody biomass were evaluated as a substrate for secondary lactic acid bacteria (LAB) fermentation in sour beer production. XOS were extracted from birch (Betula pubescens) and added to beer to promote the growth of Lactobacillus brevis BSO 464. Growth, pH, XOS degradation, and metabolic products were monitored throughout fermentations, and the final beer was evaluated sensorically. XOS were utilized, metabolic compounds were produced (1800 mg/L lactic acid), and pH was reduced from 4.1 to 3.6. Secondary fermentation changed sensory properties significantly, and the resulting sour beer was assessed as similar to a commercial reference in multiple attributes, including acidic taste. Overall, secondary LAB fermentation induced by wood-derived XOS provided a new approach to successfully produce sour beer with reduced fermentation time (from 1-3 years to 4 weeks). The presented results demonstrate how hemicellulosic biomass can be valorized for beverage production and to obtain sour beer with improved process control.

Optimization of protein fractionation by skim milk microfiltration: Choice of ceramic membrane pore size and filtration temperature.

The objective of this study was to investigate how ceramic membrane pore size and filtration temperature influence the protein fractionation of skim milk by cross flow microfiltration (MF). Microfiltration was performed at a uniform transmembrane pressure with constant permeate flux to a volume concentration factor of 2.5. Three different membrane pore sizes, 0.05, 0.10, and 0.20µm, were used at a filtration temperature of 50°C. Furthermore, at pore size 0.10µm, 2 different filtration temperatures were investigated: 50 and 60°C. The transmission of proteins increased with increasing pore size, giving the permeate from MF with the 0.20-µm membrane a significantly higher concentration of native whey proteins compared with the permeates from the 0.05- and 0.10-µm membranes (0.50, 0.24, and 0.39%, respectively). Significant amounts of caseins permeated the 0.20-µm membrane (1.4%), giving a permeate with a whitish appearance and a casein distribution (αS2-CN: αS1-CN: κ-CN: ß-CN) similar to that of skim milk. The 0.05- and 0.10-µm membranes were able to retain all caseins (only negligible amounts were detected). A permeate free from casein is beneficial in the production of native whey protein concentrates and in applications where transparency is an important functional characteristic. Microfiltration of skim milk at 50°C with the 0.10-µm membrane resulted in a permeate containing significantly more native whey proteins than the permeate from MF at 60°C. The more rapid increase in transmembrane pressure and the significantly lower concentration of caseins in the retentate at 60°C indicated that a higher concentration of caseins deposited on the membrane, and consequently reduced the native whey protein transmission. Optimal protein fractionation of skim milk into a casein-rich retentate and a permeate with native whey proteins were obtained by 0.10-µm MF at 50°C.

Ex vivo Digestion of Milk from Red Chittagong Cattle Focusing Proteolysis and Lipolysis.

Ex vivo digestion of proteins and fat in Red Chittagong Cattle milk from Bangladesh was carried out using human gastrointestinal enzymes. This was done to investigate the protein digestion in this bovine breed's milk with an especial focus on the degradation of the allergenic milk proteins; αs1-casein and ß-lactoglobulin and also to record the generation of peptides. Lipolysis of the milk fat and release of fatty acids were also under consideration. After 40 min of gastric digestion, all the αs-caseins were digested completely while ß-lactoglobulin remained intact. During 120 min of duodenal digestion ß-lactoglobulin was reduced, however, still some intact ß-lactoglobulin was observed. The highest number of peptides was identified from ß-casein and almost all the peptides from κ-casein and ß-lactoglobulin were identified from the gastric and duodenal samples, respectively. No lipolysis was observed in the gastric phase of digestion. After 120 min of duodenal digestion, milk fat showed 48% lipolysis. Medium (C10:0 to C16:0) and long (≥C17:0) chain fatty acids showed 6% to 19% less lipolysis than the short (C6:0 to C8:0) chain fatty acids. Among the unsaturated fatty acids C18:1∑others showed highest lipolysis (81%) which was more than three times of C18:2∑all and all other unsaturated fatty acids showed lipolysis ranging from 32% to 38%. The overall digestion of Bangladeshi Red Cattle milk was more or less similar to the digestion of Nordic bovine milk (Norwegian Red Cattle).

Relating fatty acid composition in human fingertip blood to age, gender, nationality and n-3 supplementation in the Scandinavian population.

This study investigated data obtained from whole blood fatty acid (FA) composition of 3476 Norwegian and Swedish individuals, which provided background information including age, gender, nationality and self-motivated n-3 supplement consumption. The aim of this paper was to statistically relate this background information on the subjects to their whole blood FA profile, focusing mainly on the n-3 polyunsaturated FA (PUFA). Results showed that age had significant effects on the content of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in blood lipids for the Norwegian individuals, while n-3 PUFA supplementation had a positive effect on EPA and DHA content in whole blood for the investigated population. Gender differences were also found for individual FA. A correlation also exists with previous studies on the FA profiling of blood lipids, further validating the test procedure.

Oxidative properties of lactoferrins of different iron-saturation in an emulsion consisting of metmyoglobin and cod liver oil.

Lactoferrins (LFs) at iron-saturation 8 (native) and 100%, respectively, were present in an oil-in-water (O/W) emulsion composed of 5% (w/v) cod liver oil (CLO) and metmyoglobin (metMb) in 50mM phosphate buffer at pH 6.0. Initially both LFs acted as antioxidants and reduced initial peroxide formation, but after 48h holo LF revealed the most peroxides but the least trienes. Native LF (0.8mg/ml) gave the highest (p<0.05) amounts of lipid derived volatiles after 48h incubation at 4°C. Both LFs gave similar increases in adducts to metMb with time. The most extensive aggregation induced by radicals or peroxides was found for native LF. The results pointed at reactions at the O/W interphase as highly influential for lipid and protein oxidation kinetics. Added ascorbic acid (1mM), however, behaved as an antioxidant in the pro-oxidative oil-in-water emulsion system and prevented lipid degradation and protein adductation as well as protein aggregation.

Oxidative Stability of Polyunsaturated Edible Oils Mixed With Microcrystalline Cellulose.

The oxidative stability of mixtures of edible oils containing polyunsaturated fatty acids (PUFA) and microcrystalline cellulose (MCC) was investigated. The mixtures studied consisted of oils of either camelina (CAM), cod liver (CLO), or salmon (SO) mixed with either colloidal or powdered MCC. A 50:50 (w/w) ratio of oil:MCC resulted in an applicable mixture containing high levels of PUFA edible oil and dietary fiber. The oxidative stability of the formulated mixtures and the pure oils was investigated over a period of 28 days. The peroxide value (PV) was assessed as a parameter for primary oxidation products and dynamic headspace gas chromatography mass spectrometry (GC/MS) was used to analyze secondary volatile organic compounds (VOC). CAM and the respective mixtures were oxidatively stable at both 4 and 22 °C during the storage period. The marine oils and the respective mixtures were stable at 4 °C. At 22 °C, an increase in hydroperoxides was found, but no increase in VOC was detected during the time-frame investigated. At 42 °C, prominent increases in PV and VOC were found for all oils and mixtures. Hexanal, a common marker for the degradation of n-6 fatty acids, propanal and 2,4-heptadienal (E,E), common indicators for the degradation of n-3 fatty acids, were among the volatiles detected in the headspace of oils and mixtures. This study showed that a mixture containing a 50:50 ratio of oil:MCC can be obtained by a low-tech procedure that does not induce oxidation when stored at low temperatures during a period of 1 month.

Long-term stability of a Raman instrument determining iodine value in pork adipose tissue.

The stability of a calibration model from a non-destructive Raman instrument during a period of three years was studied. A calibration model created on a dataset measuring pork adipose tissue in 2005 determining iodine value (IV), was transferred to a dataset measuring pork adipose tissue three years later in 2008. During these three years the fibre optic cable had been changed and the output of the laser was reduced to 60% compared with the power in 2005. The samples were also taken from different parts of the carcass. Aligning the peak positions and pre-processing with multiplicative scatter correction together with a selection of wavelengths/wavenumbers gave, for IV, a correlation coefficient of 0.95 for measured versus predicted IV of the 2008 samples. The accuracy expressed as root mean square error of prediction was 2.04 g iodine added to 100g of melted fat with 6 partial least squares factors for the 2008 samples. This study shows that it is possible, with minor modifications, to transfer the model from spectra measured three years later on the same instrument. It is concluded that a quantitative use of Raman instruments are robust over time.

A GC-magnetic sector MS method for identification and quantification of fatty acids in ewe milk by different acquisition modes.

A general method for qualitative and quantitative determination of fatty acids (FAs) using GC-MS was developed and tested on ewe milk. A total number of 38 poly unsaturated FAs, monounsaturated FAs and saturated FAs, from C6:0 to C24:1, were used in a comparative study of scan, reconstructed ion chromatogram and SIM. Fatty acid methyl esters in standard solutions as well as in milk from ewe were analyzed by these techniques, using a sector instrument. Instrument precision, linearity, LOD and LOQ, as well as calibration behavior and response factors were investigated for each approach. The quantitative results obtained by each technique were compared. All techniques had values for LOD and LOQ in the ng/mL region.

Determination of omega-6 and omega-3 fatty acids in pork adipose tissue with nondestructive Raman and fourier transform infrared spectroscopy.

In order to predict omega-6 and omega-3 fatty acids in the diet of humans, seventy-three pork back fat adipose tissue samples were measured with Raman spectroscopy directly on adipose tissue and on melted fat. Melted fat samples were, in addition, measured with Fourier transform infrared (FT-IR) spectroscopy. Gas chromatography analyses were conducted as the reference analysis. Partial least squares regression (PLSR) was used to calibrate and validate all models predicting omega-3 and omega-6 fatty acids contents from spectra. Omega-6 fatty acids in melted fat measured with FT-IR was predicted with a correlation coefficient (R) of 0.93 and a root mean square error of cross-validation (RMSECV) of 1.61% of the total amount of fatty acids. Raman spectra measured on melted fat gave a prediction of omega-6 fatty acids with R=0.97, and RMSECV=0.99% of total amount of fatty acids. Omega-6 fatty acids were predicted with R=0.94, and RMSECV=1.50% of the total amount of fatty acids using Raman spectra recorded on adipose tissue. For omega-3 fatty acids, the highest R=0.91, and lowest RMSECV=0.23% of the total amount of fatty acids were obtained from Raman spectra acquired on melted fat. FT-IR and Raman spectroscopy may be used as rapid, nondestructive methods to determine omega-6 and omega-3 fatty acids in melted fat. Raman spectroscopy can also be used directly on adipose tissue.

Quantitative determination of saturated-, monounsaturated- and polyunsaturated fatty acids in pork adipose tissue with non-destructive Raman spectroscopy.

The composition of dietary fat has received increased attention during the recent years because it influences human health. Seventy seven samples from pork adipose tissue and melted fat from the same tissue were measured with Raman spectroscopy. Gas chromatography analysis was conducted as reference. Iodine values (IV) ranged from 58.2 to 90.4g iodine added per 100g fat. Polyunsaturated fatty acids (PUFA) ranged from 7.8% to 31.7% and monounsaturated fatty acids (MUFA) from 35.2% to 51.5% of total fatty acids. When applied on pre-processed spectra of melted fat, partial least square regression (PLSR) with cross-validation gave a correlation coefficient (R)=0.98, and root mean square error of cross-validation (RMSECV)=1.4 for IV, using 3 PLS factors in the model. PUFA gave R=0.98 and RMSECV=1.0% of total fatty acids, using 5 PLS factors. MUFA were predicted with R=0.96 and RMSECV=1.0% of total fatty acids, using 9 PLS factors. On adipose tissue a model with 3 PLS factors gave R=0.97 and RMSECV=1.8 for IV. For PUFA, a model with 3 PLS factors gave R=0.95 and RMSECV=1.5% of total fatty acids. For MUFA a model with 6 PLS factors gave R=0.91 and RMSECV=1.5% of total fatty acids. The results indicate the feasibility to use Raman spectroscopy as a rapid and non-destructive method to determine IV, PUFA, MUFA and saturated fatty acids (SFA) measured directly on pork adipose tissue and in melted fat from the same tissue.