Fat-free Milk Research Articles

Screening and safety assessment of migrating substances released from biodegradable packaging materials into milk

Biodegradable polymeric packaging materials are being studied for their potential to replace traditional petroleum-based ones for food contact applications. However, potential safety concerns associated with the utilization of these biodegradable polymers have not been studied in detail. In this study, we conducted non-targeted screening and migration studies on two types of biodegradable milk packaging materials, which were composed of a mixture of polylactic acid (PLA), poly(butylene adipate-co-terephthalate) (PBAT), polybutylene succinate (PBS), and cellulose. In particular, we monitored the transfer of migrating substances from the packaging materials into a food simulant (50% ethanol) and into a real food (fat free and whole milk). A screening study identified seven compounds in the biodegradable packaging bags, including degradation products of antioxidants, lubricants, and plasticizers such as triethylene glycol, diethyl succinate, glycerin, 2,4-di-tert-butylphenol, and 13-docosenamide were identified. The migration studies indicated that the types and amounts of migrating substances transferred into the real food were appreciably lower than those transferred into the food simulant. Most of the detected migrating substances were below the levels established in the European Union regulations. However, the triethylene glycol levels (68-144 mg/kg) in the food simulant exceeded the limits (60 mg/kg) for one of the packaging materials tested. A safety assessment suggested that there is a low level of safety risk associated with one of the biodegradable packaging materials. This study provides important insights into the safety of biodegradable packaging materials that might be used in the food industry.

Matrix effect on the Effectiveness of High Hydrostatic Pressure Treatment on Antibiotic Residues

The use of antibiotics in agriculture and livestock poses health risks to consumers. Treatments such as High Hydrostatic Pressure (HHP) have been shown to reduce antibiotic and pesticide residues in food. This study aims to investigate the matrix effect on the effectiveness of HHP on hydrochloride tetracycline (HTC) and sulfathiazole (STZ) residues in spiked food matrices. The effect of viscosity, as well as carbohydrate, protein, and fat content on the effectiveness of HHP on antibiotic residues, was investigated. The studied matrices were full-fat and fat-free bovine milk and model food systems consisting of aqueous solutions of sugars, aqueous solutions of proteins, and oil in water emulsions. Model food systems were also used to study the viscosity effect. These systems consisted of aqueous solutions of honey, aqueous solutions of apple puree, and aqueous solutions of glycerol. The HHP processing (580 MPa, 6 min, 25 °C) took place under industrial conditions. For both antibiotics, the concentration of sugars and proteins was found to affect the effectiveness of treatment. The concentration of oils affected treatment efficacy only for HTC. Reduction of antibiotics by HHP was also affected by the type of carbohydrate and the viscosity. In conclusion, the composition and the viscosity of the food matrix exert a variable effect on the studied antibiotic residues reduction by HHP indicating different underlying mechanisms of the interactions between food constituents and antibiotics under the same process conditions.

The effects of endurance physical exercise with fat-free milk intake as a therapy for metabolic syndrome and/or sarcopenia

Background: Nutrition and exercise are important factors for addressing metabolic syndrome and sarcopenia as they are related to insulin secretion. Proteins, particularly branched-chain amino acids (BCAAs), have insulinotropic effects, while exercise reduces insulin secretion. It is thus important to investigate the effects of protein intake and exercise alone and in combination to determine suitable dietary and exercise therapies for treating metabolic syndrome and sarcopenia. Methods: Eight healthy young adult female volunteers participated in a crossover trial consisting of two 5-day experiments. Days 1 and 2 comprised a body-weight-maintained adjustment period during which the participants consumed control diets (energy, 2,010 kcal; protein, 51.9 g). Days 3 to 5 comprised the treatment period during which the participants consumed experimental diets (energy, 2,010 kcal; protein 82.3 g) containing 402 kcal of fat-free milk, and either performed only normal daily activities (non-Ex) or performed normal daily activities and exercised on a bicycle with an ergometer at a target intensity of about 50% of the maximal oxygen intake, expending 402 kcal of additional energy (Ex). Total urine samples were collected during the daytime (6:45 to 18:45) and nighttime (18:45 to 6:45 the next morning). Fasting blood samples were collected early in the morning before and after the treatment period. Results: Plasma valine, leucine, and BCAA levels were significantly elevated after both the non-Ex and Ex periods. Serum insulin levels were significantly elevated only after the non-Ex period. Urinary C-peptide immunoreactivity excretion levels increased significantly during the non-Ex period, but they decreased significantly during the Ex period. After the Ex period, the serum triglyceride and remnant lipoprotein-cholesterol (RLP-C) levels were significantly decreased. Homeostatic model assessment for insulin resistance (HOMA-IR) and atherosclerosis index (AI) values were slightly, yet significantly, increased after the non-Ex period, but were unchanged after the Ex period. The degree of change (Δ) in the RLP-C level significantly and positively correlated with the Δ HOMA-IR and Δ AI.

Differential effects of milk, yogurt, and cheese on energy homeostasis and brown adipose tissue phenotype in high-fat diet-induced obese mice.

Aim: We hypothesized that milk, yogurt, and cheese have differential impacts on energy expenditure (EE) and obesity in mice fed a high-fat diet (HFD). Methods: C57BL/6 mice (n = 16 per group) were fed a HFD or a HFD supplemented with fat-free milk (MILK), fat-free plain yogurt (YOG), or reduced-fat cheddar cheese (CHE; 19 kcal% fat), each provided at 10% of the daily energy intake, for 8 weeks. EE was quantified using a metabolic chamber. Metabolic pathways related to BAT mitochondrial function and uncoupling protein 1 (UCP1) abundance were assessed. Serum lipidomic profiles were analyzed to identify potential mediators of the observed effects. Results: MILK supplementation lowered weight gain and fat accumulation and enhanced EE and BAT thermogenesis, perhaps via the SIRT1-AMPK-PGC1α axis in BAT. This led to elevated UCP1 abundance and enhanced the abundance of hormone-sensitive lipase (HSL). MILK also altered serum lipid species, indicating enhanced energy use, and promoted BAT thermogenesis and mitochondrial function pathways. YOG exhibited a similar pattern but a lower magnitude of effects than MILK on reducing weight gain and fat mass, increasing EE, and BAT thermogenic proteins, including AMPK-PGC1α-UCP1. Both MILK and YOG showed a relative increase in serum PC 15:0_15:0 and LPC 15:0. In contrast, CHE reduced weight gain and increased EE without impacting BAT thermogenesis proteins or serum lipid species. Conclusion: Our study showed that MILK, YOG, and CHE reduced weight gain in mice on a HFD by increasing EE. MILK and YOG also up-regulated BAT thermogenesis, while both additionally altered lipids involved in fat metabolism and inflammation. CHE did not affect BAT thermogenesis and lipid species compared to HFD.

The Physicochemical, Textural, Microbiological and Sensory Properties of Skimmed Buffalo Milk Yoghurt with Tragacanth Gum During Storage.

In the food industry, research interest in the functional effects of natural polysaccharides from plants has increased in recent years. Tragacanth gum is used in dairy products because of its stabilising, thickening, fat-replacing and prebiotic properties. However, skimmed milk is considered a significant commercial loss in the production of buffalo clotted cream. Therefore, the aim of the present study is to investigate the potential of tragacanth gum in the production of yoghurt from buffalo milk residues with different concentrations of tragacanth gum (0.5, 1 and 1.5 g/L). Skimmed buffalo milk with different concentrations of tragacanth gum was pasteurised and, after cooling at 45 °C, a starter culture was added to each sample. All samples were fermented to a pH=4.80±0.2. The gross composition, acidity, water activity, water-holding capacity, whey separation, mass fractions of organic acids and volatile aroma compounds, counts of total aerobic mesophilic bacteria, yeasts and moulds, Lactococcus spp. and Lactobacillus spp. as well as sensory and textural properties were analysed during 15 days storage. The results showed that the use of tragacanth gum increased the dry matter mass fraction, water-holding capacity and mass fraction of proteins in the samples, while whey separation decreased as the concentration of gum increased. The addition of gum improved textural properties and hardness of the yoghurt. In terms of consistency, the sample with 1 g/L tragacanth gum was the most reliable. In the control group, the total aerobic mesophilic bacteria count was highest on the first and last day of storage. According to the results of the sensory evaluation, the sample with 0.5 g/L tragacanth gum was the most favourable. Research has shown that the use of stabilisers in varying ratios improves the quality of yoghurt made from fat-free buffalo milk, which is a by-product of industrial production. So instead of ending up as industrial waste, it is recycled and its value is increased.

More than fat – Proteins in dairy and plant milks contribute to the reduction of oral burn from capsaicin

The effectiveness of cow’s milk in reducing capsaicin-induced burn is well-known, and typically attributed to capsaicin’s lipophilicity. Still, controlled laboratory studies show full-fat milk is not more efficacious than fat-free milk, suggesting other components may contribute to milk’s effectiveness. Recent research has shown milk proteins like micellar casein and whey reduce capsaicin burn in the absence of fat. This paper reports two experiments in moderate capsaicin users that investigate the efficacy of dairy and plant milks varying in fat and protein content. In Experiment One, participants were exposed to 5-ppm capsaicin solutions before rinsing with conventional full-fat milk, ultra-filtered full-fat milk, almond milk, soy milk, and pea protein-enriched flax milk. In Experiment Two, they rinsed with fat-free, conventional full-fat, and ultra-filtered full-fat milk, and three soy milks of varying protein content. Participants made burn ratings on a general Labelled Magnitude Scale (gLMS) once every 10 s for 2-min (Experiment One) or continuously for 2-min (Experiment Two). Experiment One showed significant main effects of time and sample, with planned comparisons revealing differences for water versus conventional and ultra-filtered full-fat milk. In Experiment Two, a main effect of time and a time-by-sample interaction were observed, with samples in both blocks (soy milk, dairy milk) significantly outperforming water. Some evidence of a concentration-dependent effect was observed for protein, with both experiments suggesting ultra-filtered high protein full-fat milk was most efficacious. These findings suggest proteins play a role in mitigating capsaicin burn, although further research is needed to quantify the relative contributions of fat and protein.

Investigation on Bacterial Growth and pH in Milk after the Expiration Date.

Food waste is a serious national and global problem. Milk is one of the most frequently wasted food items. This study aims to determine how long postexpiration-pasteurized milk may still be safe to consume and what is the relationship between bacterial growth from the milk and time after expiration. The experiments were carried out by incubating milk with agarose gel. The results showed that the bacterial growth was relatively low for at least the first few days after expiration. The more the days passed after the expiration date, the more the bacteria grew from the milk. There was no significant difference in the bacteria colony numbers in the whole milk samples opened either on day 0 or day 5 of expiration. None of the fat-free milk samples collected on the later (1-10) days showed any statistically significant difference in bacterial growth compared to the samples collected on the day after expiration (day 0). The bacterial growth increased with the increasing fat content of the milk. In addition, the rate of bacterial growth from the milk correlated with the acidity of the milk that is measured by pH. No significant sensory changes could be detected in any of the milk samples immediately after opening on the day of expiration or for up to 10 days after expiration when the unopened cartons were kept refrigerated. However, within 24 hours of opening the carton, whole milk that has expired for 6 or more days and 2% milk that has expired for 8 or more days developed a sour taste and mildly pungent smell. This sensory change was accompanied by the formation of lumps and fat-water separation. Fat-free milk samples remained unchanged under the same conditions. The experimental results suggest that whole and 2% skim milk may be safe for consumption up to 5-6 days after expiration. Fat-free milk may be safe for consumption up to 10 days after expiration, possibly longer. This study devised a way to show that milk is still safe for consumption after expiration; it will help reduce food waste.

Biological activity of dried infused sapodilla (Manilkara zapota) leaf tea formulated with different milk and sugar contents

Milk tea is a popular global beverage, but it also has high sugar and fat contents that can lead to chronic diseases. Sapodilla (Manilkara zapota) leaves contain various phenolic compounds with significant antioxidant and health benefits, but the biological impacts of interactions between sapodilla and other food ingredients in food systems have not been investigated. This study assessed ingredient interactions with the biological properties of functional sapodilla milk tea. Dried sapodilla leaves were infused with hot water at 1 g/120 mL and 1 g/68 mL and formulated with almond milk, soy milk, fat-free cow milk, and lactose-free cow milk. Each formulation was determined for color, total phenolic content, and total antioxidant activity using ABTS and FRAP assays. Two sweeteners, white sugar and smart-branded sugar, were added and tested for antioxidant capacity and sensory acceptability. The formulations were measured for estimated glycemic index (GI), antioxidant capacity, and sensory acceptability compared to commercial products. Results revealed a prototype with a lower estimated GI than commercial products (p<0.05) and high overall liking score of 7.6 (n=30). Functional ingredients from natural sources such as sapodilla leaves can be successfully incorporated into foods, providing novel functional product categories and new commercial opportunities.

Resistive Switching Property of Raw Organic Cow Milk for Memory Application

Organic material-based computer memory devices are critical for lowering the amount of electronic waste. Toward this end, we here present the resistive switching property of metal-insulator-metal type devices consisting of active layers made of raw organic cow milk. Our devices were made up of fat-free, medium cream, and full cream raw cow milk active layers sandwiched between indium-doped tin oxide and silver electrodes. These devices were created without the use of heat or electricity, and because they use cow milk as their active layers, they do not pollute the environment. The medium-fat milk film had a higher weight percentage of metallic ions than the fat-free and full-cream milk films, according to energy-dispersive X-ray spectroscopy analysis of the active layers. As a result, electrical characterization and memory studies revealed that conductive filaments driven by a space-charge-limited conduction mechanism were responsible for the “S-type” memory characteristics of the medium-fat milk-based device, with switching at remarkably low VSET=+0.48V and VRESET=−0.25V. Furthermore, with over 30 write/erase cycles, this device demonstrated better non-volatile computer memory device prospects. Hoping conduction-driven conductive filaments, on the other hand, were linked to the behavior of devices that use fat-free and full-cream milk. Overall, our findings show that the fat and ion content of milk plays an important role in the morphology, transport, and switching of these devices.

Inline Particle Size Analysis during Technical-Scale Processing of a Fermented Concentrated Milk Protein-Based Microgel Dispersion: Feasibility as a Process Control

Particle size is not only important for the sensory perception of fat-free fermented concentrated milk products, but also for processing operations because of the direct relationship with apparent viscosity. The aim of this study was to apply inline particle size analysis using focused beam reflectance measurement (FBRM) to obtain real-time information regarding the particle size of a fat-free fermented concentrated milk product, namely, fresh cheese. By comparing inline particle size data to offline particle size, apparent viscosity, protein content and processing information, the potential to use inline particle size analysis as a process monitoring and control option during fresh cheese production was assessed. Evaluation of inline particle size after fermentation and before further processing, e.g., after a buffering tank, shows promise as a means to control variance of product entering downstream processing and, thus, improve final product consistency over time. Measurement of inline particle size directly before filling could allow for precise control of final product characteristics by the use of mechanical or mixing devices placed before the inline measurement. However, attention should be given to the requirements of the inline measurement technology for accurate measurement, such as product flow rate and pressure.

Gastric epithelial response to milk fat using the semi-dynamic INFOGEST digestion model coupled with NCI-N87 cells

The stomach is a relevant spot of lipolysis for milk fat, but research on the effect of digested milk fat in the gastric epithelium is scarce and difficult to evaluate. In the present study, we implemented the semi-dynamic in vitro digestion model of INFOGEST, combined with gastric NCI-N87 cells, to study the effect of fat-free, whole conventional, and whole pasture-based milk on gastric epithelium. Cellular messenger ribonucleic acid (mRNA) expression of membrane fatty acids receptors (GPR41, GPR84), antioxidant enzymes (CAT, SOD, GPX), and inflammatory molecules (NF-κB p65, IL-1β, IL-6, IL-8 and TNF-α) was assessed. No significant differences were observed in mRNA expression of GPR41, GPR84, SOD, GPX, IL-6, IL-8, and TNF-α, after exposure of the NCI-N87 cells to milk digesta samples (p > 0.05). An increase of CAT mRNA expression was observed (p < 0.05), at a similar level, for all milk types. Whole milk digested samples induced higher mRNA expression of NF-κB p65 and IL-1β than fat-free milk (p < 0.05); while no differences were observed between whole conventional and whole pasture-based milk (p > 0.05). Moreover, the effect of milk digesta on gastric mRNA expression was studied in a scenario of subsequent stimulation of NCI-N87 monolayer with the pro-inflammatory cytokine IFN-γ. In these conditions, milk digesta samples increased CAT mRNA expression (p < 0.05), but had no effect in the expression of NF-κB p65 and IL-1β (p > 0.05). The increase of CAT mRNA expression suggests that milk fatty acids are used for energy production by gastric epithelial cells. Cellular antioxidant response to higher milk fatty acids availability could be associated to gastric epithelial inflammation, but did not contribute to increased inflammation in case of an external contact with IFN-γ. Besides, a conventional or a pasture-based origin did not affect the impact of whole milk in the NCI-N87 monolayer. The combined model responded to differences in milk fat content, which indicates its usefulness to study effects of foods at the gastric level.

Milk-Derived Carbon Quantum Dots: Study of Biological and Chemical Properties Provides Evidence of Toxicity.

Carbon dots (CDs) are carbon-based zero-dimensional nanomaterials that can be prepared from a number of organic precursors. In this research, they are prepared using fat-free UHT cow milk through the hydrothermal method. FTIR analysis shows C=O and C-H bond presence, as well as nitrogen-based bond like C-N, C=N and -NH2 presence in CDs, while the absorption spectra show the absorption band at 280 ± 3 nm. Next, the Biuret test was performed, with the results showing no presence of unreacted proteins in CDs. It can be said that all proteins are converted in CDs. Photo luminance spectra shows the emission of CDs is 420 nm and a toxicity study of CDs was performed. The Presto Blue method was used to test the toxicity of CDs for murine hippocampal cells. CDs at a concentration of 4 mg/mL were hazardous independent of synthesis time, while the toxicity was higher for lower synthesis times of 1 and 2 h. When the concentration is reduced in 1 and 2 h synthesized CDs, the cytotoxic effect also decreases significantly, ensuring a survival rate of 60-80%. However, when the synthesis time of CDs is increased, the cytotoxic effect decreases to a lesser extent. The CDs with the highest synthesis time of 8 h do not show a cytotoxic effect above 60%. The cytotoxicity study shows that CDs may have a concentration and time-dependent cytotoxic effect, reducing the number of viable cells by 40%.

Sex-specific Feeding Behavior of Adult House Flies, Musca domestica L. (Diptera: Muscidae).

House flies, Musca domestica L., (Diptera: Muscidae) mechanically vector diverse disease-causing microorganisms while foraging for food in agricultural and urban habitats. Although flies are diverse feeders, nutrient composition of food is important for both fly longevity and reproduction, especially for anautogenous females who require protein for egg production. We investigated whether fly sex and/or mating status influenced their preference for foods with varying macronutrient composition. Presumably mated or unmated male and female flies were separated by sex and offered four food, each in 10% solution offered on cotton wicks: sugar (carbohydrate-rich), fat-free milk (protein-rich, moderate carbohydrate), egg-yolk (protein and lipid-rich), and water (no macronutrients). Foods were colored with nontoxic dyes, which were rotated between replicates. After 4h exposure, flies were dissected to determine the type of food(s) ingested. The interaction of house fly sex and food type significantly influenced food preference, where females preferred milk (protein and carbohydrate-rich food), and males preferred mainly sugar (carbohydrate-rich). Furthermore, 32.8% of females and 10.6% of males foraged on multiple foods. While interaction of sex and mating status had no effect on food preference, milk preference was significantly higher in presumably mated than unmated females. We also tested whether food color influenced fly feeding preference, and found that color was most significant when flies were offered one food type, but negligible when multiple food types were present. This study suggests that bait-based fly control strategies should consider sex-specific preferences for various food attractants if aiming to target and control both male and female house flies.

The effect of the feed additive "Relikt A®" on the blood and milk parameters of newborn cows

This work is devoted to the study of the effect of the 4% feed additive "Relikt A®", which includes a complex of humic substances, on the morphological and biochemical parameters of blood, the physico-chemical composition of milk, namely, the content of milk protein, fat (their ratio), dry fat-free milk residue, density, acidity and conductivity. As a result of the studies on the 30th day, it was found that with the introduction of a 4% feed additive "Relict A®" into the diet at a dose of 200 mg/kg of live weight, the total protein in the blood serum of the experimental group exceeded the control values by 12,06% (pЈ0,01**), albumin - by 7,86% (рЈ0,05*), globulins - by 14,87% (рЈ0,01**), urea - by 21,33% (рЈ0,05*), calcium - by 17,41% (pЈ0.05*), calcium to phosphorus ratio - by 42,97% (pЈ0,001***), magnesium - by 8,14% relative to control values. According to the physicochemical analysis of milk after 14 days of the experiment, it was noted that the milk protein in the experimental group is higher than the control values by 8,00% (pЈ0,05*), the ratio of fat to protein is lower by 31,90% (pЈ0,05*). On the 30th day of the experiment, it was noted that the milk protein of the experimental group of animals is higher than the control ones by 8,36% (pЈ0,05*), SOMO (dry skimmed milk residue) - by 8,39% (pЈ0,05*), acidity is lower by 11,35% (рЈ0,01**). The introduction of the "Relikt A®" feed additive into the diet at a dose of 200 mg/kg optimizes the biochemical processes of the body of cows in the early period after calving, reduces the risk of ketosis and hypocalcaemia, and ensures the absorption of dietary nutrients, which is expressed in the corresponding physicochemical parameters of milk.

Conjugated linoleic acid isomers induced dyslipidemia and lipoatrophy are exacerbated by rosiglitazone in ApoE null mice fed a Western diet

BACKGROUND: Insulin sensitizers have been used to treat Type 2 diabetes. However, their non-negligible side effects have led to cardiovascular concerns and the withdrawal of a member, rosiglitazone. OBJECTIVE: We combined conjugated linoleic acid (CLA) with rosiglitazone to test for amelioration of side effects posed by rosiglitazone in vivo. METHODS: We utilized ApoE null mice fed with Western diet (WD) to test our hypothesis. Mice were fed WD, with or without CLA administration, for 12 weeks. CLA utilized in our study consisted of a 1:1 ratio of 95% pure c9,t11, and t10,c12 isomers at a concentration of 0.1% w/v in fat-free milk. Starting from Week 12, select mice received rosiglitazone. RESULTS: It was found that mice receiving CLA from Week 0 and rosiglitazone from Week 12 had the lowest body weight and exacerbated hepatomegaly. Although these mice had attenuated insulin resistance compared to mice receiving only Western diet, they display a marked increase in total plasma cholesterol and low-density lipoprotein (LDL) cholesterol. Mice receiving early CLA administration developed hyperleptinemia, which was not restored by rosiglitazone. CONCLUSION: Taken together, against the background of ApoE null genotype and WD feeding, simultaneous administration of 1:1 CLA and rosiglitazone led to dyslipidemic lipoatrophy.

Storage temperature effect on structural elements of ice cream

In the transportation and sale of ice cream, fluctuations in air temperature are possible with an excess of the recommended temperature minus 18 ° C. During subsequent storage, this leads to a change in the dispersion of structural elements (ice crystals and air bubbles) and the appearance of organoleptic defects. The article presents the results of studying the effect of temperature fluctuations on the dispersion of structural elements using the example of ice cream with the most effective stabilization system under conditions of realistically possible temperature fluctuations. The object of the study was ice cream with a mass fraction of fat 10%, dry fat-free milk residue 10%, sucrose 14%, and with a complex stabilizer-emulsifier containing 0.35% of an emulsifier with a high demulsifying effect (mono- and diglycerides with a high content of unsaturated fats) and a synergistic composition of hydrocolloids (0.15%) (locust bean gum and guar and carrageenan). It was found that a threefold change in the product temperature in the range of minus 18 ° C – minus 12 ° C – minus 18 ° C and subsequent storage for six months leads to an increase in the average size of ice crystals by 35%, and in the control sample only by 6%. In this case, for three months of storage, the angles with a larger base of the crystal increase by at least 10 ° C. During the same period, the average diameter of the air bubble increased by 61%. In the control sample, the air bubble increased by 26%. Frozen should not be stored until sale for a long time, for example, more than one month. This recommendation is to avoid a decrease in the fineness of structural elements ice cream subjected to a threefold increase in temperature from minus 18 ° C to minus 12 ° C with subsequent freezing to minus 18°C even when using an effective stabilizer.

Tailoring the Textural Characteristics of Fat-Free Fermented Concentrated Milk-Protein Based Microgel Dispersions by Way of Upstream, Downstream and Post-Production Thermal Inputs.

There is a growing demand for new strategies to tailor the texture of fat-free fermented concentrated milk products, also referred to as milk protein-based (MPb) microgel dispersions. Methods should be easy to incorporate into the production scheme, offer labelling without added components and be cost-efficient. Thermal treatments are traditionally used upstream (milk heating) and downstream (pre-concentration heating) in the production of these dispersions, though there is little knowledge as to the effects that combinations of different thermal input levels have on final texture. Therefore, this study investigated combinations of thermal input at different intensities and steps in the production scheme at the pilot scale and the relationships with texture. We demonstrated that increasing the intensity of upstream milk heat treatment, in combination with downstream pre-concentration heating, increases gel firmness and apparent viscosity. Downstream pre-concentration heating produces final fat-free fermented concentrated MPb microgel particles that are resistant to post-heating aggregation. On the other hand, omission of downstream pre-concentration heating results in smaller particles that are sensitive to post-heating aggregation. Furthermore, gel firmness and apparent viscosity increase with post-heating. Consequently, combining different levels of thermal inputs upstream, downstream (pre-concentration) and post-production, can produce fat-free fermented concentrated MPb microgel dispersions with a range of different textures.

Fat-free fermented concentrated milk protein-based microgel dispersions manufactured at technical scale: Production parameters as drivers of textural properties

Fat-free fermented concentrated milk products, recently classified as dispersions of (fat-free) fermented concentrated milk protein-based microgel particles, are basically produced by upstream, fermentation, and downstream processing. Development of production parameters aimed at, e.g., increasing yield, shelf-stability, and reducing acid whey, has led to a variety of possible parameters at each production stage. Though the influences of some individual parameters on the final textural properties are well understood, combinations of parameters and outcomes in large technical scale production environments are not well documented. Production parameters of six fat-free fermented concentrated milk products from technical scale production were reviewed and parallels were drawn between chemical composition, serum release, particle size, and rheological properties. In order of importance, the five parameters of downstream standardisation, pre-heating, concentration method, addition of rennet during fermentation and fermentation temperature/time were identified as main textural drivers, by initiating changes of microgel particle voluminosity, surface properties, size, and composition.

Fat-free fermented concentrated milk products as milk protein-based microgel dispersions: Particle characteristics as key drivers of textural properties.

The popularity of fat-free fermented concentrated milk products, such as fresh cheeses and high-protein yogurt, has increased over the recent years, attributed to greater availability and improvements in taste and texture. These improvements have been achieved through modifications and new developments in processing technologies, for example, higher heat treatment intensities and incorporating different membrane filtration technologies. Though numerous processing parameters are discussed in the literature, as well as reasons behind the developments, detailed examinations of how process modifications affect the final textural attributes of these products are lacking. To draw links between processing parameters and texture, we review the literature on fat-free fermented concentrated milk products from the perspective of fermented milk protein-based microgel particles as the basic structural unit. At each main processing step, relationships between process parameters, micro- and macrostructural and sensory (textural) properties are discussed.An overview of particle characteristics that drive structural changes at each processing step is developed in relation to textural characteristics. Using this approach of assessing relationships between structural characteristics of concentrated dispersions of fat-free fermented milk protein-based microgel particles and processing parameters provides a basic context for the selection of optimal parameters to achieve a desired texture.

The effect of high-pressure jet processing on cocoa stability in chocolate milk

Fat-free chocolate milk formulations containing skim milk, cocoa powder, and sugar were thermally treated and then processed using high-pressure jet (HPJ) technology from 125 to 500 MPa. The rheological properties and stability of HPJ-treated chocolate milks were compared with controls (no HPJ processing) prepared both with and without added κ-carrageenan. As expected, carrageenan-free chocolate milk exhibited immediate phase separation of the cocoa powder, whereas formulations containing κ-carrageenan were stable for 14 d. An increased stability was observed with increasing HPJ processing pressure, with a maximum observed when chocolate milk was processed at 500 MPa. The apparent viscosity at 50 s-1 of HPJ-processed samples increased from ~3 mPa·s to ~9 mPa·s with increasing pressure, and shear-thinning behavior (n < 0.9) was observed for samples processed at HPJ pressures ≥250 MPa. We suggest that HPJ-induced structural changes in casein micelles and new casein-cocoa interactions increased cocoa stability in the chocolate milk. Because casein seemed to be the major component enhancing cocoa stability in HPJ-treated samples, a second study was conducted to determine the effect of additional micellar casein (1, 2, or 4%) and HPJ processing (0-500 MPa) on the stability of fat-free chocolate milk. Formulations with 4% micellar casein processed at 375 and 500 MPa showed no phase separation over a 14-d storage period at 4°C. The addition of micellar casein together with HPJ processing at 500 MPa resulted in a higher apparent viscosity (~17 mPa·s at 50s-1) and more pronounced shear-thinning behavior (n ≤ 0.81) compared with that without added micellar casein. The use of HPJ technology to improve the dispersion stability of cocoa provides the industry with a processing alternative to produce clean-label, yet stable, chocolate milk.