Milk Foam Research Articles

Effect of sonication time on physical and foaming properties of pasteurized milk

This study investigates the impact of ultrasonication duration on the properties of milk foam. Milk samples were subjected to ultrasonication for varying durations (1, 3, 5, 7, and 10 min), resulting in different sizes of native fat globules (249.5, 221.5, 222.6, 207.5, and 244.8 nm, respectively). The results indicate that viscosity increases as fat globule size decreases, with slight effect on zeta potential. NanoFoamer was identified as the optimal method providing the highest between foamability and stability (p < 0.05). Notably, foaming performance decreases after 7 min of sonication, highlighting the importance of selecting an appropriate frothing method to achieve the desired foam characteristics. Comparisons with non-ultrasonicated milk suggest that ultrasonication duration not only influences foamability by reducing fat globule size but also enhances foam stability through alterations in the fat globule sizes. Analysis of the foam structure revealed that smaller fat globules initially produce smaller, more numerous air bubbles with polyhedral shapes and well-defined lamellae. However, excessive reduction in fat globule size destabilizes the foam due to competitive protein adsorption and altered membrane composition, resulting in larger, less stable bubbles over time. Exploring ultrasonication times to enhances quality of milk and foam properties, offering significant benefits for dairy processing, product innovation and customer satisfaction.

The bubbly life and death of animal and plant milk foams.

Milk foams are fragile objects, readily prepared for frothy cappuccinos and lattes using bovine milk. However, evolving consumer preferences driven by health, climate change, veganism, and sustainability have created a substantial demand for creating frothy beverages using plant-based milk alternatives or plant milks. In this contribution, we characterize maximum foam volume and half-lifetime as metrics for foamability and foam stability and drainage kinetics of two animal milks (cow and goat) and compared them to those of the six most popular, commercially available plant milks: almond, oat, soy, pea, coconut, and rice. We used three set-ups: an electric frother with cold (10 °C) and hot (65 °C) settings to emulate the real-life application of creating foam for cappuccinos, a commercial device called a dynamic foam analyzer or DFA and fizzics-scope, a bespoke device we built. Fizzics-scope visualizes foam creation, evolution, and destruction using an extended prism-based imaging system facilitating the capture of spatiotemporal variation in foam microstructure over a broader range of heights and liquid fractions. Among the chosen eight milks, oat produces the longest-lasting foams, and rice has the lowest amount and stability of foam. Using the hot settings, animal milks produce more foam volume using an electric frother than the top three plant milks in terms of foamability (oat, pea, and soy). Using the cold settings, oat, soy, and almond outperform cow milk in terms of foam volume and lifetime for foams made with the frother and sparging. Most plant milks have higher viscosity due to added polysaccharide thickeners, and in some, lecithin and saponin can supplement globular proteins as emulsifiers. Our studies combining foam creation by frothing or sparging with imaging protocols to track global foam volume and local bubble size changes present opportunities for contrasting the physicochemical properties and functional attributes of animal and plant-based milk and ingredients for engineering better alternatives.

Foaming properties of milk samples collected at various processing stages in a dairy processing factory across two seasons.

A foam layer makes an essential contribution to the quality of cappuccino-style drinks. Poor foaming of milk occurs quite often, however, especially in summer. The reasons for this are still unknown. Although a substantial number of studies on the foaming process of milk have been reported, these studies have been laboratory based and have used laboratory or pilot-scale equipment to simulate the processing conditions of a dairy processing factory. This study collected about 40 different samples across different processing stages in a dairy factory over two seasons (two batches per season) and investigated their composition and physical and foaming properties by mechanical mixing and steam injection. The results showed that milk samples collected in summer had a significantly higher content of fat, free fatty acids, and Ca2+ ions, and larger particle sizes but a markedly lower concentration of protein and solid non-fat, and surface tension than the samples collected in spring. These differences provided spring milk with a higher steam injection foamability than summer milk. However, steam injection foam stability, and mechanical mixing foamability and foam stability were not affected by seasonal factors. Milk samples collected in different batches within a season were almost identical with regard to the properties that were investigated. The variations in composition and physical properties of milk collected between two seasons could be the reasons for their difference in foamability but not for foam stability. Processes such as standardization, homogenization, and pasteurization improved markedlythe foaming properties of milk. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Лексическое поле үрүмэ ‘молочная пенка’ в якутском языке: нормативно-диалектный и сравнительно-сопоставительный аспект

Данное исследование проведено в контексте сохранения и документирования диалектной лексики якутского языка. Необходимость изучения литературно-нормативных и диалектных наименований молочных продуктов (блюд) в якутском языке обусловлена тем, что недостаточно изучена лексика скотоводческой культуры. Изучение гастрономической лексики позволит не только выявить семантические схождения и отличия, но и познакомиться с культурой традиционной пищи родственных и неродственных народов. Основная цель данного исследования заключается в описании лексического поля наименования молочного продукта үрүмэ ‘молочная пенка’ в якутском языке в сопоставлении с тюркскими и монгольскими языками. В работе предпринята попытка выявить и определить структурные и семантические особенности лексического поля үрүмэ ʻмолочная пенкаʼ, провести сравнительно-сопоставительный анализ наименований молочной пенки в тюркских и монгольских языках. Для решения поставленной цели работы, выполненной в традициях лингвокультурологии, использованы контекстный анализ, описательный метод и интерпретация языкового материала. Приводятся лексикографические примеры, выдержки из этнографических материалов, раскрывающие лексические значения отдельных слов. Определена структура слов, которые являются гастрономическими терминами, обозначающими различные блюда из молочной пенки. Выявлены их форманты, отмечены компоненты составных терминов. Анализ показал, что в хакасском, тувинском, тофаларском и якутском языках присутствуют наименования молочной пенки үрүмэ//өрөмө, которые имеют схождения в монгольских языках. Устанавливается связь наименования молочной пенки көпүк//күбек в тюркских языках с общетюркским значением именной основы көп* ʻобильный, большой, пышныйʼ, имеются лексические схождения с диалектными номинациями взбитых сливок (көбүкү, көөп и др.) в якутском языке. Наименования видов сливочного масла в якутском языке (көбүөр, көбдө арыы, көбүөр арыы) обнаруживают семантические параллели с монгольской основой көп* cо значением ʻрыхлыйʼ. Выявлено также, что монгольской лексике близки якутские наименования сушеной молочной пенки тарчаа, таччаҕа, чачык, чаччык, чаччаа, чаччаҕа. Описание подтвердило, что в лексическое поле «Үрүмэ» включаются наименования-архаизмы глиняной посуды для приготовления блюд из молочной пенки (баҕарах, түптэх). Установлена коннотативная семантика степени жирности молока в цветообозначающем компоненте кыһыл үрүмэ. The vocabulary of cattle breeding has not been sufficiently studied in the Yakut language. The study of dialect names of dairy products (dishes) remains relevant. The purpose of this study is to describe and analyze the lexical field of the name of dairy product үrүme ‘milk foam’ in the Yakut language in comparison with the Turkic and Mongolian languages. To achieve the goal, the following tasks were set: to identify and determine the structural and semantic features of the lexical field үrumе ʻmilk foamʼ; to conduct a comparative and comparative analysis of the names of milk foam in the Turkic and Mongolian languages. The work uses the methods of descriptive method, contextual analysis and interpretation of linguistic material. The material and sources are explanatory, dialectological dictionaries, and ethnographic materials. In the course of the study the structure of gastronomic terms, which denote different types of dishes made of milk foam, was determined. Word-forming affixes and components of compound terms were identified. The analysis showed that the Khakass, Tuvinian, Tofalar and Yakut languages contain the names of milk foam үrүme//өrөmө. This lexical series is of Mongolian origin. In other Turkic languages, the word kopuk//kүbek is used to denote milk foam. The basis of these names is the Turkic word kөp* with the meaning ʻgreat, large, lushʼ. The Turkic word kөp* is expressed by dialectal nominations of whipped cream in the Yakut language (kөbүkү, kөp, etc.). Yakut names of butter (kobүөr, kөbdө aryy, kobүөr aryy) are close to the Mongolian base kөn* with the meaning ʻlooseʼ. The Mongolian lexicon is close to the Yakut nominations of dried milk foam (chachyk, chachchaa, etc.). The lexical field of milk foam includes the names of earthenware utensils (baҕarakh, tүptekh) for preparing dishes from milk foam. The connotative semantics of the degree of milk fatness in the color- denoting component kyhyl үrүme was established.

Effect of steam frothing on milk microfoam: Chemical composition, texture, stability and organoleptic properties

This study focuses on the evaluation of microfoam produced from processed dairy milk using the steaming function of the espresso machine as a function of temperature (30–80 °C), milk type (pasteurised or UHT), and whey protein contents. Foam characteristics, i.e., foam stability, viscosity, bubble size distribution noticeably varied depending on milk processing type and steam heating temperature. Foams made from pasteurised whole milk tended to be more stable. Bubbles in pasteurised milk foam were better distributed, especially at the temperature of 60 °C. It was observed that the optimal final temperature of steam frothing was in the range of 50 °C–60 °C. The results of sensory tests showed that consumers differentiated between the aroma and flavour of pasteurised and UHT milk, describing the degree of this difference from moderate to strong.

Impact of temperature and surfactant addition on milk foams

Abstract Milk is a complex colloidal solution. Knowledge of milk composition assay is essential for better applications in the dairy industry apart from processing and storage. Several techniques are reported in literature, but their applications are limited due to chemical entailment, invasive nature, and complicated procedures. The present work investigates the possibility of using milk foam properties as composition markers of milk. Surfactants play a key role in generating foams. In the present work, the effect of surfactants and temperature on foams produced from milk of different fat composition was investigated. Temperature effects and the impact of cationic, anionic, and non-ionic surfactants on foams produced from three milk types (cow milk, toned milk, and full cream milk) were studied. Toned milk added with an anionic surfactant sodium dodecyl sulphate (SDS) at 60 °C showed comparatively higher foamability of 122.4 mL. Among pure milk samples, toned milk showed a comparatively higher foamability of 114.65 mL. Cationic surfactant cetyltrimethylammonium bromide (CTAB) showed better milk foaming properties. Tween 80, a non-ionic surfactant showed a minimal or neutral effect on foam properties of milk. The results attained could lay the foundations for developing a novel milk assay protocol with the use of surfactant foams and thermal pre-treatments.

Stability, temperature dependence, and microstructure of high pressure jet-treated dairy foams

The objective of this work was to study the effects of high pressure jet (HPJ) processing on the foaming of whole milk at different temperatures. High pressure jet-treated whole milk (200 and 400 MPa) was foamed at 5, 20, 40, and 50 °C using a custom-made air injection device and the foam expansion and foam stability was compared to a non-HPJ-treated control. Aliquots of the foams (formed at 5 and 50 °C) were extracted for proximate analysis and visualization using confocal scanning laser microscopy (CSLM). The relative foam expansion values for the non-HPJ-treated sample at 5, 20, 40, and 50 °C were 45.5 ± 11.3%, 0 ± 0%, 79.6 ± 9.7%, and 88.2 ± 2.8%, respectively while the 400 MPa-treated sample foam expansion values were 36.4 ± 10.8%, 60.8 ± 5.7%, 50.0 ± 5.3%, and 71.7 ± 3.0%. Notably the HPJ-treated sample foamed at 20 °C while the control milk did not foam at all. Furthermore, the 400 MPa-treated foam was stable for >2 h at all foaming temperatures, unlike the non-HPJ-treated whole milk foam, which completely collapsed in 60 s and 1490 s after being foamed at 5 °C and 40 °C, respectively. CSLM and proximate analysis of the non-HPJ-treated sample revealed differences in foam composition based on foaming temperature with more fat present in the foam formed at 50 °C (3.2 ± 0.3%) than at 5 °C (2.5 ± 0.1%), likely due to the ability of liquid oil (at 50 °C) to migrate to the air-water interface during air incorporation. In contrast, there were no compositional differences in the foams from 400 MPa-treated milk based on foaming temperature, reflecting that there are structural differences, particularly in the fat, compared to the non-HPJ-treated foams. This was supported by evidence of fat-protein complexation and micron-size bubbles in CSLM images of the 400 MPa-treated foam.

Development of soy milk in the form of wet foam in the presences of whey protein concentrate and polysaccharides at different whipping temperatures: Study of physical, rheological and microstructural properties

The aim of current work was generation soy milk in the form of the wet foam and clarify the controlling factors of foamability and foam stability. Soy milk foam (SMF) was prepared with the help of whey protein concentrate (3 and 6% w/w) and hydrocolloids (xanthan, guar and locust bean gums (0.05 and 0.15% w/w) at different temperature (5, 40 and 75°C). The overrun of SMFs was not greatly impacted by increasing guar gum concentration from 0.05% to 0.15%, whereas foam stability was greatly enhanced. When 0.15% xanthan gum was added to the samples, a great decrease on drainage was observed but they showed the lowest overrun. Also, in general, SMFs produced at temperatures of 5 and 75°C showed the highest overrun and stability, respectively. To summarize the basic physical properties of foam data (overrun, and drainage), hierarchical clustering analysis was performed. Samples from different classes evaluated for surface tension, zeta potential, rheological behavior and bubble properties to find factors controlling the formation and stability of foams. It was observed that the SMFs exhibited viscoelastic properties. Results showed that foam stability was directly related to rheological parameters (consistency coefficient, static and dynamic yield stress, zero shear viscosity, storage modulus, loss modulus, complex modulus and complex viscosity) and, except one sample, showed a negative correlation with surface tension. Overrun showed a positive correlation with the bubble counts and a negative correlation with the average bubble diameter. But microstructure changes cannot necessarily represent foam stability. Also, zeta potential could not explain any differences in the foam properties.

In-situ rheological and structural characterization of milk foams in a commercial foaming device

Processing, stability and sensorial perception of food foams are tightly related to their microstructure and flow behavior. Characterization of corresponding physical parameters is central for product development and quality control. An experimental setup enabling in-situ characterization of yield stress, gas volume fraction and bubble size distribution at different heights within a foam column created in a commercial whipping device is presented. Reliable determination of these quantities is shown. Foams made from regular and reconstituted milk have been investigated. Gas volume fraction and bubble size increase monotonically during free drainage. Related to the changes in these parameters, the yield stress increases strongly during initial drainage and weaker in mature foams. Gradients of the structural and rheological parameters along the direction of gravity increase over time. Yield stresses in these milk foams are as predicted from phenomenological modelling including the above parameters, emphasizing the reliability of the measurement setup. • In-situ characterization of milk foam shows vertical gradients in foam structure and yield stress. • Average bubble size and distribution span both increase linearly with drainage time. • Average bubble size increases with height and the gradient increases with time. • Foam yield stress and gas volume fraction increase with foam age and height in foam.

Изучение структурно-механических характеристик ферментированных взбитых молочных продуктов

Introduction. Whipped dairy products can be used both as finished and semi-finished products in confectionery industry. Therefore, this sphere constantly requires new technologies. A wide range of additives, stabilizers, and structure-forming agents make it possible to get products with programmed sensory, structural, and mechanical properties. Enzymatic processing of milk base is one of the modern directions in the development of whipping process, as it requires no artificial components. Enzyme preparations of plant and microbial origin were developed to satisfy the needs of the increasing production demand and to compensate for the acute shortage of animal rennet. These enzymes have a high proteolytic activity and exhibit good technological properties in dairy industry. The research objective was to study the fermentation process with preparations of different origin and optimize the proteolysis process to obtain a milk base with a high foaming capacity and maximal stability.&#x0D; Study objects and methods. The research featured samples of fermented reduced skim milk. The following enzymes were selected for enzymatic hydrolysis: animal origin – rennet-beef enzyme SG-50 (Russia), chicken-beef enzyme KG-50 (Russia), pepsin (Russia); microbial nature – Fromase 750 (France), Pronase E (Russia); recombinant chymosin-preparation CHY-MAX M (Denmark). The fermented systems were tested for foaming ability, foam stability, relative content of free amino acids, and the diameter of casein micelles during hydrolysis by the ratio of the height of the foam column to the initial volume. The relative content of free amino acids was determined using the method of formal titration. The diameter of casein micelles during hydrolysis was determined by dynamic light scattering using a particle size analyzer in low-volume plastic cuvettes. These indicators were determined after inactivation of enzymes by pasteurization at 90–92°C for 3–5 sec.&#x0D; Results and discussion. Enzyme preparations of various natures were added to milk. The temperature and duration were measured as rational parameters of fermentation. After inactivation of the enzymes by pasteurization method, the foaming capacity, foam stability, and the relative content of free amino acids were determined every 30 minutes after application of the preparation. The greatest foaming properties (800%) were observed in the milk base fermented with the recombinant enzyme CHY-MAX M. However, the use of this preparation in commercial production was found undesirable due to the high activity of the enzyme and the resulting complexity of the control process. The lowest foaming ability was observed in the milk sample fermented with preparations of animal origin – SG-50, KG-50, and pepsin. The optimal foaming capacity and stable whipped mass were registered in the samples hydrolyzed with microbial preparations Fromase and Pronase. Under certain rational parameters, the foaming capacity of milk was 740% and 700%, respectively, while the stability was 80%.&#x0D; Conclusion. The research featured a comparative analysis of the foaming capacity and stability of reduced skim milk foam obtained using preparations of animal and microbial origin. The enzymes of the microbial group showed the best results for the enzymatic hydrolysis of proteins in reduced milk.

Production of milk foams by steam injection: The effects of steam pressure and nozzle design

Foam properties depend on the physico-chemical characteristics of the continuous phase, the method of production and process conditions employed; however the preparation of barista-style milk foams in coffee shops by injection of steam uses milk as its main ingredient which limits the control of foam properties by changing the biochemical characteristics of the continuous phase. Therefore, the control of process conditions and nozzle design are the only ways available to produce foams with diverse properties. Milk foams were produced employing different steam pressures (100–280kPa gauge) and nozzle designs (ejector, plunging-jet and confined-jet nozzles). The foamability of milk, and the stability, bubble size and texture of the foams were investigated. Variations in steam pressure and nozzle design changed the hydrodynamic conditions during foam production, resulting in foams having a range of properties. Steam pressure influenced foam characteristics, although the net effect depended on the nozzle design used. These results suggest that, in addition to the physicochemical determinants of milk, the foam properties can also be controlled by changing the steam pressure and nozzle design.

Effects of xanthan gum rheology on the foaming properties of whey protein concentrate

The stability of foams with whey protein concentrate (WPC) and xanthan gum (XG) were studied. Flow behavior, density, pH and average particle size of aqueous phases were evaluated (10–25% WPC, 0.05 or 0.15% XG). Flow properties of the aqueous phases were dominated by XG rheology, where a zero shear viscosity was detected before the classic shear-thinning behavior (Carreau model). In general, an increase of either XG or WPC in the mixtures resulted in an increase in zero shear viscosity, characteristic time and foaming capacity. The foam stability, evaluated by the kinetics of drainage and Ostwald ripening, also increased with WPC or XG concentration, reaching very stable milk foams. The functionality of WPC was improved by the presence of XG, likely as a consequence of biopolymer segregative interactions (thermodynamic incompatibility). Rheology of aqueous phase played a decisive role in WPC–XG foam stability.

Rheology of Milk Foams Produced by Steam Injection

Rheology of milk foams generated by steam injection was studied during the transient destabilization process using steady flow and dynamic oscillatory techniques: yield stress (τ(y) ) values were obtained from a stress ramp (0.2 to 25 Pa) and from strain amplitude sweep (0.001 to 3 at 1 Hz of frequency); elastic (G') and viscous (G″) moduli were measured by frequency sweep (0.1 to 10 Hz at 0.05 of strain); and the apparent viscosity (η(a) ) was obtained from the flow curves generated from the stress ramp. The effect of plate roughness and the sweep time on τ(y) was also assessed. Yield stress was found to increase with plate roughness whereas it decreased with the sweep time. The values of yield stress and moduli-G' and G″-increased during foam destabilization as a consequence of the changes in foam properties, especially the gas volume fraction, ϕ, and bubble size, R(32) (Sauter mean bubble radius). Thus, a relationship between τ(y) , ϕ, R(32) , and σ(surface tension) was established. The changes in the apparent viscosity, η, showed that the foams behaved like a shear thinning fluid beyond the yield point, fitting the modified Cross model with the relaxation time parameter (λ) also depending on the gas volume fraction. Overall, it was concluded that the viscoelastic behavior of the foam below the yield point and liquid-like behavior thereafter both vary during destabilization due to changes in the foam characteristics. Studying the transient rheology of milk foams during destabilization contributes to our knowledge of the relationships between the changes in foam properties: texture and mouth feel during the consumption of hot foamed beverages.

The composition of interfacial material from skim milk foams

The foaming properties of skim milk vary with temperature of foaming in the range from 5 to 85°C, with foams of maximum stability being formed at approximately 45°C. This paper reports the significance of different milk fractions in the foam and concludes that the micellar casein fraction plays an important role in stabilization of milk foam formed at higher temperatures. This finding was supported by the fact that added calcium chloride increased and calcium-chelating agents decreased foam stability. These effects were attributed to the increase and decrease, respectively, in the amount of micellar casein in the milk. Furthermore, bubble ghost material sedimented by low-speed centrifugation of foam was found to contain predominantly caseins, and electron micrographs of foams formed at 45°C clearly showed casein micelles spread over the interface. However, other structures observed in the electron micrographs suggest that soluble milk proteins and possibly polar lipids are also present in the foams and play a role in formation of milk foams.

Factors Affecting the Foaming Power and Drainage Ratio of Soy Milk Foam Composed of Microbubbles

Factors Affecting the Foaming Power and Drainage Ratio of Soy Milk Foam Composed of Microbubbles

Foaming properties of milk: A review of the influence of composition and processing

Milk foams can be either desirable, e.g. for cappuccino‐style beverages, or undesirable, e.g. in the reconstitution of milk powders or infant formula. In this article, compositional and processing factors affecting the foaming properties of milk are reviewed. Skim milk foams can be extremely stable, particularly when they are formed at ∼40–50°C. The presence of lipids can be detrimental to the formation and stability of milk foams, particularly at a temperature where the milk fat is partially crystalline, e.g. 20°C. The presence of phospholipids, free fatty acids and partial glycerides strongly impairs foaming of milk.

Effect of protein content, casein–whey protein ratio and pH value on the foaming properties of skimmed milk

The average bubble diameter (ABD) and density of skimmed milk foam decreased with increasing protein content, up to 4%, while drainage was widely comparable. Samples with casein–whey protein ratios (C/W) of 94/6 and 7/93 showed smaller ABD than samples from mixtures with C/W ratios between 60/40 and 20/80. Foams prepared from samples with C/W of 20/80 exhibited the lowest drainage values after 10 min. Increasing pH from 6.4 to 7.0 led to increased overrun and ABD, while drainage was widely comparable, with a minimum value at pH 6.7. The protein composition of skimmed milk and foams prepared from this milk in relation to protein content, C/W ratio and pH value differed only slightly.

The influence of temperature on the foaming of milk

The effect of temperature (5–85 °C) on the foaming properties of cows' milk was investigated. The foaming properties of milk as a function of temperature varied considerably depending on fat content and the processing conditions used in manufacture. Skim milk foams were most stable when formed at 45 °C. Milk fat had a detrimental effect on foam formation and stability of whole milk especially in the temperature range 15–45 °C. The detrimental effects of milk fat on foaming properties were reduced by homogenization and ultra-high-temperature (UHT) treatment. No correlation was observed between foam formation and surface tension of whole milk in the temperature range15–45 °C. There was a pronounced difference in the bubble size distributions of whole milk and skim milk especially at half-life of the foams. Bubbles in whole milk foams were smaller and showed a higher degree of rupture as a result of coalescence than those in skim milk foams.

Inactivation of Staphylococcus aureus in Milk and Milk Foam by Pulsed UV-Light Treatment and Surface Response Modeling

Pulsed UV-light is a novel technology that can be used for effective inactivation of pathogens. In this study, efficacy of pulsed UV-light (100 to 1100 nm) was investigated for the inactivation of Staphylococcus aureus (ATCC 25923) in milk and milk foam, due to its pathogenic effect in milk and milk products. Static cell suspensions of 12, 30, or 48 mL in milk were treated under pulsed UV-light for 30, 105, or 180 s at various distances (8, 10.5, and 13 cm for milk, and 5, 8, and 11 cm for milk foam). Reductions varied from 0.16 to 8.55 log10 CFU/mL, demonstrating the ability of pulsed UV-light to inactivate S. aureus. Complete inactivation was obtained at: (1) 8 cm sample distance from the quartz window of the UV-light source, 30 mL sample volume, and 180 s time combination; and (2) 10.5 cm sample distance, 12 mL sample volume, and 180 s treatment time combination. Reductions up to 6.61 0.11 log10 CFU/g were obtained in milk foam for various treatment conditions. It was noted that there was a significant increase in the milk temperature (up to 90C in some cases) during pulsed UV-light treatment, which might have also provided synergistic effect on microbial inactivation.

Skim milk powders with enhanced foaming and steam-frothing properties

The effects of citrate addition to milks on the stability of milk foams formed by two aeration processes, whipping at room temperature and by steam-frothing, were examined. Citrate addition (0.1–0.5 mol added citrate·kg−1 milk solids non-fat) improved the whipping properties of milks reconstituted from conventional low-heat (72 °C for 30 s) and high-heat (85 °C for 30 min) powders. This effect was attributed to the role of citrate in dissociating casein micelles. However, while citrate addition (0.1–0.2 mol added citrate·kg−1 milk solids non-fat) improved the steamfrothing properties of milks reconstituted from conventional low-heat milk powder it did not improve those of milks made from corresponding high-heat milk powders. Similar effects of citrate addition on foaming and stream-frothing properties were obtained when the salts were added to skim milk concentrate prior to drying. The citrated milk powders are alternatives to physical blends of conventional skim milk powders and citrate salts for enhancing the foaming properties of milks at both low and high application temperatures.