Effect of hybrid drying on the quality attributes of formulated instant banana-milk powders and shakes during storage.

The present research aimed to evaluate the effect of microwave-assisted conventional drying (hybrid drying) on the physico-chemical and functional characteristics of formulated instant banana-milk powders (IBSPs), and organoleptic attributes of banana-milk shakes during storage. The instant powders were prepared from ripe (IBSP1 (control) and IBSP2) and overripe (IBSP3) bananas using hot-air drying (control) and hybrid (microwave assisted hot-air) drying. The water holding capacity, water solubility index, and viscosity of fresh samples, IBSP1, IBSP2, and IBSP3 were 1.97, 1.53 and 0.60 g/g dry sample, 69.48, 75.21 and 76.62 g/mL and 82.29, 86.29 and 72.55 mPas, respectively. A significant (p < 0.05) increase in moisture content, water activity (aw), acidity, and non-enzymatic browning was observed in all the variants/samples during storage. Among various treatments, the shakes prepared by reconstitution (IBSP: water ratio, 1:4) of IBSP2 formulation rated highest organoleptically (significant, p < 0.05).

The Effect of Carnosol, Carnosic Acid and Rosmarinic Acid on the Oxidative Stability of Fat-Filled Milk Powders throughout Accelerated Oxidation Storage.

The in vitro antioxidant effects of the most potent antioxidants of rosemary, namely carnosol, carnosic acid and rosmarinic acid (c: ca: ra) were assessed in fat-filled milk powders (FFMPs) under accelerated conditions (40 °C and relative humidity (RH) 23%) over 90 days. Lipid oxidation was assessed in FFMPs by measuring peroxide values (PVs), thiobarbituric acid reactive substances (TBARS) and aroma volatiles using headspace (HS) solid-phase microextraction (SPME) coupled to gas-chromatography-mass spectrometry (GC-MS). The antioxidant potency of c: ca: ra exhibited a concentration-related effect (308 ppm > 200 ppm > 77 ppm), with the highest concentration being the most effective at controlling the formation of TBARS and PVs. At a concentration of 308 ppm c: ca: ra were particularly effective (p < 0.05) in inhibiting all the evaluated oxidation indices (primary and secondary) compared to the control samples, but in some cases less effectively (p < 0.05) than butylated hydroxyanisole: butylated hydroxytoluene (BHA: BHT) (200 ppm).

Novel choline selective electrochemical membrane sensor with application in milk powders and infant formulas.

Choline (Ch+), is a vitamin-like essential water-soluble organic micronutrient. The US-FDA requires that infant formula not made from cow's milk must be supplemented with Ch+. Direct determination of Ch+ in milk powders and infant formulas is a challenging task due to the lack of a detectable chromophore, its existence in free and complexed forms as well as the presence of multi-analytes in these complex matrices. Here, an enzyme-free potentiometric ion selective electrode (ISE) with high selectivity for Ch+, a linear range from 0.03 µM up to 1 mM, a 0.061 µM detection limit (LOD) and a typical response time less than 5 and no greater than 60 s is developed for monitoring of Ch+ in infant formula and milk powders. To achieve these ISE parameters we relied on the ability of calixarenes and its derivatives to form host-guest complexes with the positively charged quaternary ammonium moiety of Ch+. We employed a lipophilic (membrane-compatible) calixarene as an ionophore in the sensing membrane phase to provide a molecular receptor for Ch+ capable of selective binding; while utilizing, hydrophilic (water-soluble) p-sulfonated calixarene as a buffering agent to optimize the inner filling solution to reduce transmembrane Ch+ fluxes. All the calixarene structures and their complexes with Ch+ were optimized at the density functional theory (DFT) level and the Gibbs free energies for the inclusion of Ch+ into the calixarenes were calculated. The prepared sensor was shown to selectively respond only to Ch+ in the presence of all other interferents in the tested matrices with results that are not statistically significantly different for either accuracy or precision relative to the much more laborious official AOAC 1999 coupled enzymatic-spectrophotometric method. The proposed method is highly selective, non-enzymatic, requires no derivatization or incubation steps, offers a fast response time, and has the potential of portability for in situ analysis, while being relatively cost effective and non-laborious.

Mild mixed-solvent extraction for determination of total mineral oil hydrocarbon contaminants in milk powder products.

A mild mixed-solvent of n-hexane/isopropanol is proposed for extracting total mineral oil hydrocarbons (MOH) from commercial milk powder products. Unlike acid-hydrolysis, the mixed-solvent extraction was performed at ambient temperature and the low-boiling-point hydrocarbons were retained to the greatest extent. After extraction, total MOH was determined by on-line liquid chromatography-gas chromatography with a flame ionization detector (LC-GC-FID). The validation of the proposed extraction method revealed a recovery efficacy of 83.0-107.5% and a limit of quantification of 0.5 mg/kg. Then, the total MOH in ten commercial milk powders was determined and mineral oil saturated hydrocarbons (MOSH)/polyolefin oligomeric saturated hydrocarbons (POSH) were found to be within the range of 0.61-5.46 mg/kg. The comparison of the total and surface MOSH/POSH indicated that a major part of the contamination was derived from sources before packaging. The present study provides a robust method for the extraction and determination of total MOH in milk powders.

Characterisation of the quality alterations in model fat-filled milk powders under inclement conditions and the prediction of the storage time using near infrared spectroscopy.

Fat-filled milk powders (FMP) are exported to tropical developing markets as inexpensive milk alternatives. Consequently, FMP are exposed to high temperature and humidity over long distribution and storage times, presenting challenges in preserving product quality and stability. Efficient and cost-effective methods for quality assurance under such conditions are needed. We utilised the changes in profile of the fatty acids, amino acids and near infrared spectra to investigate the quality alterations in 4 types of FMP produced onsite with 4 different vegetable oils (i.e., coconut, palm, soya-bean and sunflower) and stored for 7 weeks at 40 °C. Stearic acid decreased while the leucine content increased upon storage, but palm oil FMP appeared to be the most stable. Multiclass analyses offered substantive separation between fresh and aged samples. The models based on interval-PLS efficiently (NSE ≥ 0.90) predicted storage time with low errors (RSR ≤ 0.28), indicative of FMP freshness and stability.

Study on screening potential allergenic proteins from infant milk powders based on human mast cell membrane chromatography and histamine release assays.

Cow's milk allergy is mainly observed in infants and young children. Most allergic reactions affect the skin, followed by the gastrointestinal and respiratory systems. Conventional diagnosis is based on positive allergy studies and evaluation of parameters including IgE and IgG1 levels, acute allergic skin response and anaphylactic shock reactions. We developed a cell membrane chromatographic (CMC) method based on human mast cells (HMC-1) for screening potential allergens in infant formula milk powders (IFMP). HMC-1 cell membranes were extracted and mixed with silica to prepare cell membrane chromatography columns (10 mm × 2 mm i.d., 5 µm). Under the conditions of 0.2 mL/min flow rate and 214 nm detection wavelength, human breast milk showed no retention. However, IFMP showed clear retention. The retained fractions were collected and analyzed through matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS). Four major milk proteins, i.e., α-casein, ß-casein, α-lactalbumin, and ß-lactoglobulin A, were identified. Furthermore, these proteins and ß-lactoglobulin B showed clear retention on HMC-1/CMC columns. To test the degranulation effects of the five proteins, histamine and ß-hexosaminidase release assays were carried out. All five proteins induced HMC-1 cells to release histamine and ß-hexosaminidase. Also, we established a reversed phase liquid chromatographic (RPLC) method for the determination of the five proteins in IFMP and the results showed that 90% proteins in IFMP were α-casein and ß-casein. We concluded that cow's milk proteins may be potential allergens and caseins cause more ß-casein allergic risk than other proteins. This conclusion was consistent with other studies.

Study on screening potential allergenic proteins from infant milk powders based on human mast cell membrane chromatography and histamine release assays / 药物分析学报

Cow's milk allergy is mainly observed in infants and young children. Most allergic reactions affect the skin, followed by the gastrointestinal and respiratory systems. Conventional diagnosis is based on po-sitive allergy studies and evaluation of parameters including IgE and IgG1 levels, acute allergic skin response and anaphylactic shock reactions. We developed a cell membrane chromatographic (CMC) method based on human mast cells (HMC-1) for screening potential allergens in infant formula milk powders (IFMP). HMC-1 cell membranes were extracted and mixed with silica to prepare cell membrane chromatography columns (10 mm × 2 mm i.d., 5 mm). Under the conditions of 0.2 mL/min flow rate and 214 nm detection wavelength, human breast milk showed no retention. However, IFMP showed clear retention. The retained fractions were collected and analyzed through matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS). Four major milk proteins, i.e., α-casein, β-casein, α-lactalbumin, and β-lactoglobulin A, were identified. Furthermore, these proteins and β-lacto-globulin B showed clear retention on HMC-1/CMC columns. To test the degranulation effects of the five proteins, histamine and β-hexosaminidase release assays were carried out. All five proteins induced HMC-1 cells to release histamine and β-hexosaminidase. Also, we established a reversed phase liquid chromatographic (RPLC) method for the determination of the five proteins in IFMP and the results showed that 90％ proteins in IFMP were α-casein and β-casein. We concluded that cow's milk proteins may be potential allergens and caseins cause more β-casein allergic risk than other proteins. This con-clusion was consistent with other studies.

Mining Milk for Factors which Increase the Adherence of Bifidobacterium longum subsp. infantis to Intestinal Cells.

Bifidobacteria play a vital role in human nutrition and health by shaping and maintaining the gut ecosystem. In order to exert a beneficial effect, a sufficient population of bifidobacteria must colonise the host. In this study, we developed a miniaturised high-throughput in vitro assay for assessing the colonising ability of bacterial strains in human cells. We also investigated a variety of components isolated from different milk sources for their ability to increase the adherence of Bifidobacterium longum subsp. infantis ATCC 15697, a common member of the gastrointestinal microbiota of breastfed infants, to HT-29 cells. Both conventional and miniaturised colonisation assays were employed to examine the effect of 13 different milk-derived powders on bacterial adherence, including positive controls which had previously resulted in increased bifidobacterial adherence (human milk oligosaccharides and a combination of 3'- and 6'-sialylactose) to intestinal cells. Immunoglobulin G enriched from bovine whey and goat milk oligosaccharides resulted in increased adhesion (3.3- and 8.3-fold, respectively) of B. infantis to the intestinal cells and the miniaturised and conventional assays were found to yield comparable and reproducible results. This study highlights the potential of certain milk components to favourably modulate adhesion of bifidobacteria to human intestinal cells.

Delivery of Curcumin Using Skim Milk or Oil in Water Emulsions: Effect of the Matrices on Cellular Uptake.

To enhance the curcumin delivery in a variety of food grade matrices namely spray dried ethanolic curcumin in fresh skim milk (Spray dried Cu-SM), a fresh mixture of ethanolic curcumin and skim milk (Fresh Cu-SM) a powder mixture of curcumin and skim milk powder (Powder Cu-SMP) and oil in water emulsion (Emulsion) were studied. The cellular uptake of curcumin from the respective matrices was studied on Caco-2 cell monolayers. Spray dried Cu-SM showed higher encapsulation efficiency compared to a corresponding Powder Cu-SMP and an oil-in-water emulsion (40% oil) bearing curcumin. Furthermore, ethanolic administration of curcumin in spray dried form enhanced the cellular uptake of curcumin considerably higher than non-ethanolic samples (approx. 4 times). Overall, milk protein based vectors were found to perform better than emulsion samples. These findings highlighted the fact that curcumin uptake may be tailored by fine tuning of curcumin delivery vehicles which highlights possible application of powders as functional foods.

Relationships between surface energy analysis and functional characteristics of dairy powders.

Surface energetics of demineralised whey (DMW), skimmed milk (SMP), phosphocasein (PCN) and infant milk formula (IMF) powders were determined by inverse gas chromatography (IGC). All four milk powders were amphoteric in nature with the dispersive (apolar) component of surface energy dominating the specific (polar) contribution. PCN and IMF had the highest and lowest extent of surface heterogeneity, respectively. PCN also demonstrated the poorest functional properties of the powders examined. In contrast, IMF had excellent flow and rehydration properties. Thermodynamic work of cohesion was highest in PCN and may have contributed to inadequate rehydration behaviour. Glass transition temperature of IMF powder, determined by IGC, suggested a surface dominated by lactose. Surface heterogeneity provided a better indicator of functional behaviour than total surface energy. IGC is a useful complementary technique for chemical and structural analysis of milk powders and allows improved insight into the contribution of surface and bulk factors to functionality.

A RAPD based study revealing a previously unreported wide range of mesophilic and thermophilic spore formers associated with milk powders in China.

Aerobic spore forming bacteria are potential milk powder contaminants and are viewed as indicators of poor quality. A total of 738 bacteria, including both mesophilic and thermophilic, isolated from twenty-five powdered milk samples representative of three types of milk powders in China were analyzed based on the random amplified polymorphic DNA (RAPD) protocol to provide insight into species diversity. Bacillus licheniformis was found to be the most prevalent bacterium with greatest diversity (~43% of the total isolates) followed by Geobacillus stearothermophilus (~21% of the total isolates). Anoxybacillus flavithermus represented only 8.5% of the total profiles. Interestingly, actinomycetes represented a major group of the isolates with the predominance of Laceyella sacchari followed by Thermoactinomyces vulgaris, altogether comprising of 7.3% of the total isolates. Out of the nineteen separate bacterial species (except five unidentified groups) recovered and identified from milk powders, twelve proved to belong to novel or previously unreported species in milk powders. Assessment and characterization of the harmful effects caused by this particular micro-flora on the quality and safety of milk powders will be worth doing in the future.

Application of a dye-binding method for the determination of available lysine in skim milk powders.

A dye-binding method using Acid Orange 12 was investigated regarding its suitability for the quantification of available lysine, as a means of monitoring the Maillard reaction in skim milk powders. The method was evaluated by analyzing a wide range of milk powders produced by three different drying methods and stored under various conditions. A pilot-scale freeze-dryer, spray-dryer and drum-dryer were used to produce skim milk powders and the samples were stored at two temperatures (20 °C and 30 °C) and two relative humidities (33% and 52%) under strictly controlled conditions. Moreover to validate the method, two protein isolates; bovine serum albumin and casein were investigated for their available lysine content. The results demonstrate the suitability of this method for measuring the available lysine in skim milk powders with good precision and high reproducibility. The relative standard deviations obtained from the 125 freeze-dried powders were 1.8%, and those from the 100 drum-dried samples were all 1.9%. The highest variation was found for the spray-dried powders, which showed relative standard deviations between 0.9% and 6.7%.

Determination of vitamin A and vitamin E esters in infant formulae and fortified milk powders by HPLC: Use of internal standardisation.

An HPLC method is described using normal phase conditions with an unbonded silica column to determine concentrations of supplementary vitamin A and vitamin E esters and ß-carotene in infant formulae. The method utilises selective dual-channel fluoresence for vitamins A and E and visible absorbance for ß-carotene. An attribute of the method is the use of retinol propionate, α-tocopheryl propionate and all-E-ß-apo-8'-carotenoic acid ethyl ester internal standards to compensate for analytical variations associated with these labile vitamins. Extraction is performed without saponification, with the aid of protease to remove vitamin encaspsulation and facilitate vitamin partition into hydrocarbon solvent. Figures of merit indicate the method is suitable for its intended purpose in the highly regulated infant formula environment, including liquid formulations. The method is extendable to whole milk powders where total vitamin A content data can be calculated by summing the innate long-chain vitamin A esters with the added esters.

Assessment of heat treatment of various types of milk.

Raw milk (RM), reconstituted condensed milk (CM) and three types of reconstituted milk powders (SMPs) were heated indirectly at 80-140°C for 4 s. Native ß-lactoglobulin after 90°C treatment of RM was 1132±167 mg/L but no reliable quantities were estimated at temperatures >100°C, whereas 218±43 mg/L residual α-lactalbumin were found at 130°C. Average lactulose contents from 51 to 1549 mg/L were detected at ⩾100°C; average furosine was 1.9 and 126.5 mg/L in raw and 140°C treated milks respectively. The behaviour of heated CM was similar to that of heated RM except for higher furosine concentration. Reconstituted SMPs contained high quantities of lactulose and furosine, the ratio of which was lower than in similarly treated RM. Among the market milks analysed, the group of high-pasteurised milks was highly variable; i.e. native ß-lactoglobulin was 69-2831 mg/L, lactulose 0-824 mg/L and furosine 3.3-68.8 mg/L.