Characterization and mitigation of stick-slip behavior in powders

This study aimed to determine the physicochemical properties and antioxidant activities of dromedary skim colostrum and milk powder produced by freeze-drying. Results of the study showed that skim colostrum powder possessed higher protein content compared to milk powder whereas this latter had greater lactose and ash content. The analysis of mineral content revealed that calcium and magnesium levels were higher in skim colostrum powder while the iron level did not differ significantly between skim colostrum and milk powder. The measurements of colour characteristics indicated that dromedary skim colostrum powder was redder, but less yellow and white than dromedary skim milk powder. Further, dromedary skim milk powder had higher bulk density and tapped bulk density. Protein solubility of skim colostrum powder exceeded that of skim milk powder over a wide range of pH (3-8). The antioxidant activities were evaluated using various in vitro tests, including 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2’azino-bis (3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) radical scavenging activities, ferric reducing power assay and ferrous chelating activity. Both dromedary skim colostrum and milk powder exhibited antioxidant activities in a dose dependent manner. DPPH and ABTS radical scavenging activities were almost similar for skim colostrum and milk powder whereas ferric reducing power and ferrous chelating activity were more pronounced in dromedary skim colostrum powder whatever the concentration tested. Hence, freeze-drying process could be used as an effective tool for producing powder from dromedary skim colostrum and milk with nutritional and antioxidant properties.

The lack of updated knowledge about the physical properties of milk powders aimed us to evaluate selected physical properties (water activity, particle size, density, flowability, solubility and colour) of eleven skim and whole milk powders produced in Europe. These physical properties are crucial both for the management of milk powder during the final steps of the drying process, and for their use as food ingredients. In general, except for the values of water activity, the physical properties of skim and whole milk powders are very different. Particle sizes of the spray-dried skim milk powders, measured as volume and surface mean diameter were significantly lower than that of the whole milk powders, while the roller dried sample showed the largest particle size. For all the samples the size distribution was quite narrow, with a span value less than 2. The loose density of skim milk powders was significantly higher than whole milk powders (541.36 vs 449.75kg/m3). Flowability, measured by Hausner ratio and Carr's index indicators, ranged from passable to poor when evaluated according to pharmaceutical criteria. The insolubility index of the spray-dried skim and whole milk powders, measured as weight of the sediment (from 0.5 to 34.8mg), allowed a good discrimination of the samples. Colour analysis underlined the relevant contribution of fat content and particle size, resulted in higher lightness (L*) for skim milk powder than whole milk powder, which, on the other hand, showed higher yellowness (b*) and lower greenness (-a*). In conclusion a detailed knowledge of functional properties of milk powders may allow the dairy to tailor the products to the user and help the food processor to perform a targeted choice according to the intended use.

Development and application of a processing model for the Irish dairy industry

The demand for dried starter cultures that are specific to indigenous fermented food products is increasing. In most cases, skim milk (SM) powder is used as a cryoprotectant for microbial cell protection during the preparation of starter cultures. However, the extent of cell protection during freeze-drying and the fermentation efficacy of dried cultures are dependent on the type of microbial strain and carrier media, hence the need to investigate the protective effects of alternative carrier media. This study evaluated the fermentation potential of lactic acid bacteria (LAB) preserved in coconut (CCN) powder and SM powder during ting (traditional fermented sorghum) production. Ting was fermented with single and mixed strains of Lactobacillus plantarum and Lactobacillus brevis. The pH, total titratable acidity (TTA), functional groups (Fourier transform infrared spectroscopy [FTIR]), microbial quality, and consumer acceptability were monitored during fermentation. Ting prepared with LAB strains preserved in SM had a more rapid reduction (p > 0.05) in pH and lower final pH than ting prepared with LAB preserved in CCN. Mixed LAB strains showed a rapid reduction in pH of ting compared to single LAB strains and ting prepared with spontaneous fermentation. The highest TTA (3.57%) was observed with mixed LAB after 48 h on both SM and CCN ting. FTIR showed similar functional groups corresponding to O–H and phenolic compounds for both SM and CCN ting. The highest increase in LAB counts (up to 10 log CFU/mL) occurred in ting prepared with mixed strains of both CCN and SM, while the least increase occurred with spontaneously fermented ting. Enterobacteriaceae, yeasts, and molds were not detected in all the fermented samples. With consumer acceptability, CCN ting was the most preferred sample with the highest overall score (6.95), followed by the SM ting sample (5.67). In conclusion, this work indicates that the LAB strains preserved in CCN result in comparable fermentation performance to that of SM and produce ting that is preferred by consumers. Therefore, CCN should be considered as a carrier medium for the development of ting starter cultures.

Investigation of the migration of triclabendazole residues to milk products manufactured from bovine milk, and stability therein, following lactating cow treatment

ABSTRACTFlavor variability in skim milk powder (SMP) has been documented by descriptive sensory analysis and instrumental analysis. However, research has not addressed how or if SMP flavor variability impacts consumer acceptance of ingredient applications. Twenty reconstituted low‐heat SMPs were screened using a previously established defined sensory language. Two SMPs free of off‐flavors (flavor similar to fresh fluid skim milk) and 2 SMPs exhibiting off‐flavors (exhibiting flavors not found in fluid skim milk) were selected for further study. Volatile compounds were determined using solid phase microextraction (SPME) with gas chromatography‐mass spectrometry (GC‐MS). Each SMP was subsequently directly reconstituted or incorporated into standard formulas for vanilla ice cream, strawberry yogurt, hot cocoa mix, and white chocolate bars. Consumer acceptance testing was conducted. Descriptive panelists documented sweet aromatic and cooked flavors in the fresh‐flavored SMP and these flavors as well as fatty/fryer oil and animal‐like flavors in the off‐flavored SMP. Concurrently, instrumental volatile analysis revealed higher relative abundances of lipid oxidation compounds in the off‐flavored SMP. Consumer acceptance scores were lower for the off‐flavored SMP than for the fresh‐flavored SMP when evaluated directly reconstituted (P< 0.05) and for ingredient applications made using off‐flavored SMP (P< 0.05). Off‐flavors in SMP documented by descriptive analysis and trained panelists can carry through into ingredient applications with SMP and negatively affect consumer acceptability.

Performance of Holstein calves receiving increased nutrient intake through the addition of skim milk or milk replacer powder to the whole milk

Risk evaluation for staphylococcal food poisoning in processed milk produced with skim milk powder

The chemical composition of two types of milk powder - whole and skim milk was studied. The richest in protein is skimmed milk powder. The possibility of using skimmed milk powder in compound feed for rainbow trout has been established. Compound feed formulations have been developed with partial replacement of fish meal with skimmed milk powder. The modes of extrusion were selected for compound feeds containing a heat-sensitive component - milk powder. It was found that the optimal percentage of skimmed milk powder is 10%. It was found that compound feed containing 10% skimmed milk was used 1.8 times more effectively in the fish organism compared to the control. The coefficient of protein utilization when feeding with compound feed with 10% input of skimmed milk powder is 1.1 times higher, and the accumulation of substances in the body of rainbow trout is 40% more intensive. The nutrient content in the compound feed containing 10% skimmed milk per kilogram of rainbow trout growth is 1.4 times higher than in the control. To increase the efficiency of rainbow trout feeding, a compound feed has been developed containing 10% skimmed milk powder instead of fish meal. Modes of compound feed extrusion were selected: the optimal temperature range is 90-100 0С, the range of humidity values is 28-30%. A regression equation was obtained that adequately describes the change in the content of essential amino acids with an increase in the extrusion temperature in the composition of a compound feed containing 10% skimmed milk powder, empirical coefficients of the regression equation were selected.

Enhancing yield and acceptability of Kareish cheese made of Reformulated milk

The influence of bovine diet on the metabolome of reconstituted skim milk powder (SMP) and protein ingredients produced from the milk of cows fed on pasture or concentrate-based diets was investigated. Cows were randomly assigned to diets consisting of perennial ryegrass only (GRS), perennial ryegrass/white clover sward (CLV), or indoor total mixed ration (TMR) for an entire lactation. Raw milk obtained from each group was processed at pilot scale, to produce SMP and sweet whey, and SMP was further processed at laboratory scale, to yield ideal whey and acid whey. The total amino acid composition and metabolome of each sample were analyzed, using high-performance cation exchange and a targeted combination of direct-injection mass spectrometry and reverse-phase liquid chromatography–tandem mass spectrometry (LC–MS/MS), respectively. The nitrogen composition of the products from each of the diets was similar, with one exception being the significantly higher nonprotein nitrogen content in TMR-derived skim milk powder than that from the GRS system. Total amino acid analysis showed significantly higher concentrations of glycine in GRS- and CLV-derived sweet whey and acid whey than in those from TMR. The cysteine contents of CLV-derived ideal whey and acid whey were significantly higher than for TMR, while the valine content of GRS-derived acid whey was significantly higher than TMR. The phenylalanine content of GRS-derived ideal whey was significantly higher than that from CLV. Metabolomic analysis showed significantly higher concentrations of the metabolites glutamine, valine, and phosphocreatine in each ingredient type derived from TMR than those from GRS or CLV, while the serine content of each GRS-derived ingredient type was significantly higher than that in TMR-derived ingredients. These results demonstrate that the type of bovine feeding system used can have a significant effect on the amino acid composition and metabolome of skim milk and whey powders and may aid in the selection of raw materials for product manufacture, while the clear separation between the samples gives further evidence for distinguishing milk products produced from different feeding systems based on LC–MS/MS.

Plasma and hepatic cholesterol and hepatic HMG CoA reductase levels in rats fed fluid or powdered skim milk

Ten commercial samples of dry dairy products used for protein fortification in a low fat yoghurt model system at industrial scale were studied. The products employed were whey protein concentratres, milk protein concentrates, skimmed milk concentrates and skimmed milk powder which originated from different countries. The gross chemical composition of these dried products were determined, including polyacrylamide gel electrophoresis (SDS-PAGE) and isoelectric focusing of the proteins, and minerals such as Na, Ca, K and Mg. Yoghurts were formulated using a skim milk concentrated as a milk base enriched with different dry dairy products up to a 43 g kg−1 protein content. Replacement percentage of skim milk concentrated by dry dairy products in the mix was between 1.49 and 3.77%. Yoghurts enriched with milk protein concentrates did not show significantly different viscosity (35.12 Pa s) and syneresis index (591.4 g kg−1) than the two control yoghurts obtained only from skimmed milk concentrates (35.6 Pa s and 565.7 g kg−1) and skimmed milk powder (32.77 Pa s and 551.5 g kg−1), respectively. Yoghurt fortified with the whey protein concentrates, however, was less firm (22.59 Pa s) and had less syneresis index (216 g kg−1) than control yoghurts. Therefore, whey protein concentrates may be useful for drinking yoghurt production. © 1999 Society of Chemical Industry

Ten commercial samples of dry dairy products used for protein fortification in a low fat yoghurt model system at industrial scale were studied. The products employed were whey protein concentratres, milk protein concentrates, skimmed milk concentrates and skimmed milk powder which originated from different countries. The gross chemical composition of these dried products were determined, including polyacrylamide gel electrophoresis (SDS-PAGE) and isoelectric focusing of the proteins, and minerals such as Na, Ca, K and Mg. Yoghurts were formulated using a skim milk concentrated as a milk base enriched with different dry dairy products up to a 43 g kg−1 protein content. Replacement percentage of skim milk concentrated by dry dairy products in the mix was between 1.49 and 3.77%. Yoghurts enriched with milk protein concentrates did not show significantly different viscosity (35.12 Pa s) and syneresis index (591.4 g kg−1) than the two control yoghurts obtained only from skimmed milk concentrates (35.6 Pa s and 565.7 g kg−1) and skimmed milk powder (32.77 Pa s and 551.5 g kg−1), respectively. Yoghurt fortified with the whey protein concentrates, however, was less firm (22.59 Pa s) and had less syneresis index (216 g kg−1) than control yoghurts. Therefore, whey protein concentrates may be useful for drinking yoghurt production. © 1999 Society of Chemical Industry

Forty-onesamples of skim milk powder (SMP) and nonfat dry milk(NFDM) from 8 suppliers, 13 production sites, and 3 processing temperatureswere analyzed by NIR diffuse reflectance spectrometry over a periodof 3 days. NIR reflectance spectra (1700–2500 nm) were convertedto pseudoabsorbance and examined using (a) analysis of variance-principalcomponent analysis (ANOVA-PCA), (b) pooled-ANOVA based on data submatrices,and (c) partial least-squares regression (PLSR) coupled with pooled-ANOVA.ANOVA-PCA score plots showed clear separation of the samples withrespect to milk class (SMP or NFDM), day of analysis, production site,processing temperature, and individual samples. Pooled-ANOVA providedstatistical levels of significance for the separation of the averages,some of which were many orders of magnitude below 10–3. PLSR showed that the correlation with Certificate of Analysis (COA)concentrations varied from a weak coefficient of determination (R2) of 0.32 for moisture to moderate R2 values of 0.61 for fat and 0.78 for proteinfor this multinational study. In this study, pooled-ANOVA was appliedfor the first time to PLS modeling and demonstrated that even thoughthe calibration models may not be precise, the contribution of theprotein peaks in the NIR spectra accounted for the largest proportionof the variation despite the inherent imprecision of the COA values.