UHT Milk Research Articles

Phenolics in soymilk manufactured from black and Proto soybeans by two continuous-ultrahigh-temperature-processing technologies inhibit DU145-prostate cancer cell proliferation through apoptosis.

Plant genotypes and processing technologies affect health properties of foods. How thermal processes with different sterilization values influence polyphenols in soymilk manufactured from different genotypes, particularly black soybean has not been well characterized. This study's aims were to investigate how one- and two-phase ultrahigh temperature (UHT) processing technologies, with wide differences of lethality (F0 158.5 and 6.35, respectively), affected anti-prostate cancer DU145-cell properties of black soymilk compared to light-yellow-Proto soymilk. Phenolics were extracted from soymilk and used for chemical, cell cycle and apoptosis analyses. Total isoflavones and genistein in black soymilk were significantly higher than Proto soymilk by either processing methods. Compared to one-phase processing, two-phase produced higher gallic acid in both soybeans, and higher oxygen radical absorbance capacity (ORAC) in black soymilk. Soymilk processed from both genotypes by both UHT methods inhibited DU145 cells. Two-phase-UHT processed black soymilk was more effective than one-phase UHT-processed soymilk. IC50 values (mg/mL) of black and yellow soy extracts against prostate cancer cells differed only by 11%-25%, which were lower than the differences of total isoflavone (29%-33%) or genistein (>50% between two beans). The mechanism by which soymilk inhibited DU145 cell proliferation was through apoptosis as evidenced by cell cycle analyses and expressions of caspase-3, Bcl-2, and PARP-1 proteins. Antioxidant properties, isoflavones, and phenolic acids were negatively correlated with prostate-cancer-cell inhibition IC50 (p<0.05) with ORAC having the highest coefficient (r=-0.98). Overall, two-phase-UHT processing of soybean would produce soymilk products with a higher health benefit than a one-phase UHT method. PRACTICAL APPLICATION: This study characterized the potential prostate cancer prevention effect of soymilk's phenolic extract in black soybean and compared with yellow soybean. The crude extract can be prepared much less costly than purified isoflavones and has potential to be developed into a dietary supplement. This study shows differences of soymilks made by continuous high-temperature processing of two soybean types and can serve as a scientific foundation for future clinical research and commercialization.

Aflatoxin M1 level and risk assessment in milk, yogurt, and cheese in Tabriz, Iran

Aim and BackgroundThe objective of this study was to investigate the presence of aflatoxin M1(AFM1) in milk, yogurt, and cheese samples collected from Tabriz, Iran. Additionally, the study conducted a risk assessment related to the consumption of milk and dairy products within Tabriz city. Study MethodFor this study, 56 samples (raw milk, pasteurized milk, ultra-high temperature milk (UHT), traditional yogurt, pasteurized yogurt, traditional cheese, and pasteurized cheese) were collected randomly in Tabriz from December 2021 to March 2022. The analysis was carried out using liquid chromatography, which was equipped with a fluorescence detector. The estimated dietary intake (EDI) and the hazard index (HI) were calculated for the risk assessment. Results and DiscussionAFM1 was detected in all samples. The highest concentration of AFM1 was observed in traditional cheese (P<0.05). The lowest concentration was observed in UHT milk and there were no significant differences between raw milk and pasteurized yogurt(P<0.05). Moreover, in all samples, the levels of AFM1 were below the maximum limit permitted by Iranian national standards. AFM1 levels in traditional yogurt exceeded the European Union's permissible limit in 25% of the samples. The HI in all samples was less than one for both adult and child consumers, except for milk samples for children, which were more than one and indicated a medium risk. In conclusion, the levels of contamination in milk and dairy products and risk assessment appear not to pose a public health risk to Tabriz consumers.

Influence of different calcium‐chelating salts on the colloidal structure of skimmed milk under simulated heat treatment conditions

Research objective was to study the influence of calcium‐chelating salts on colloidal properties of skimmed milk, which best meets the Brazilian regulation for UHT milk production. Citrate and different ortho‐ and polyphosphate sodium salts were added to milk at 5 concentrations (0.00 up to 0.20% w/w). Samples were heat‐treated (oil bath, 155°C, F0 = 1.43 min), cooled down and analysed. The main changes were caused by tetrasodium diphosphate and sodium triphosphate at 0.15% and 0.20% w/w, as they increased the pH, sequestering capacity and altered the particle size distribution, showing that the impacts on the colloidal structure are influenced by the salt concentration.

Inovasi Bitterballen dengan Vegetable Oatmeal Bitterballen untuk Menambah Variasi Menu di Dapoer Marclip

Bitterballen is a traditional Dutch snack shaped like a ball, primarily made from flour and milk. Classic bitterballen usually contain minced beef and cheese. Its crispy exterior and soft interior make it a popular snack. In this study, the author utilizes vegetables and oatmeal to create a delicious and healthy version of bitterballen. The processing of Vegetable Oatmeal Bitterballen is in collaboration with Dapoer Marclip. The purpose of developing this product is to assess the panelists' preferences regarding appearance, color, aroma, texture, and taste, as well as to establish recipe standards. This research employs a research and development method. Data collection was conducted through organoleptic tests involving 25 participants, including lecturers, industry representatives, and consumers. Based on the results from four trials, it can be concluded that the preference levels in the main test were as follows: appearance—44% very much liked, 56% liked; color—76% very much liked, 24% liked; aroma—56% very much liked, 44% liked; texture—68% very much liked, 32% liked; taste—80% very much liked, 20% liked. Thus, it is stated that this product is well-liked and accepted by the panelists. The appropriate standard recipe formula is: 105g flour, 20g butter, 40g onion, 7g garlic, 100g spinach, 50g carrots, 85g corn, 40g mozzarella, 80g rolled oats, 1 egg, 150ml UHT milk, 120ml water, 5g MSG, 3g pepper, and 4g salt. The author suggests that future researchers consider alternative snack recipes using vegetables and appealing colors.

Eksplorasi Rasa Baru Melalui Inovasi Isian Choux Kolak Pisang untuk Meningkatkan Daya Tarik Menu

Choux craquelin is a variation of choux pastry characterized by a layer of dough on top, commonly referred to as craquelin, which becomes crunchy after baking. The primary ingredient used is wheat flour. The filling for choux typically consists of a cooled custard or cream, usually flavored with vanilla or fruit slices. In this instance, the author attempts to create a new flavor innovation for the choux au craquelin filling using kolak pisang. Kolak pisang is a sweet dish made with coconut milk and brown sugar, accompanied by the fragrant aroma of bananas, and is commonly enjoyed during certain occasions, such as Ramadan. The aim of this research is to determine the standard recipe, the level of preference for the product, and a business analysis. This study employs a research and development approach, and data collection was conducted through organoleptic testing with five expert panelists. The findings indicate that the appropriate standard recipe consists of the following: choux: 200g eggs, 120g water, 120g UHT milk, 100g margarine, 2g salt, and 150g wheat flour; craquelin: 100g butter, 100g wheat flour, and 90g granulated sugar; kolak pisang cream: 250g whipped cream, 7 pieces of jackfruit bananas, 200g palm sugar, 3 pandan leaves, 1g salt, 100g instant coconut milk, and 200g palm sugar. The business analysis revealed a food cost of Rp. 2,870 per piece, with a selling price of Rp. 8,000. The break-even point is reached by selling 442 pieces. To achieve a target profit of Rp. 3,000,000 per month, the author must sell 1,451 pieces per month. This research hopes to contribute to innovative developments in kolak pisang-based products.

High-Temperature Short-Time and Ultra-High-Temperature Processing of Juices, Nectars and Beverages: Influences on Enzyme, Microbial Inactivation and Retention of Bioactive Compounds

HTST (high-temperature short-time) pasteurization and UHT (ultra-high-temperature) sterilization are techniques commonly used in the dairy industry. Although the use of these methods in fruit and vegetable processing is also well known, the multitude of diverse food matrices determines the need to test and adjust process parameters in order to obtain the best quality of the final product. HTST and UHT are methods that provide effective inactivation of microorganisms and enzymes. Despite the fact that UHT and HTST are thermal processes that cause degradation of bioactive ingredients or color change, in many cases, these two methods are superior to traditional pasteurization, which uses significantly longer exposures to high temperatures. Therefore, this article aims to review the effect of HTST and UHT processing on the quality of juices, nectars and beverages, taking into consideration the quality characteristics, like the presence of microorganisms, pH, titratable acidity, total soluble solids, turbidity, color parameters, contents of bioactive components, antioxidant activity, enzymatic activity and volatile compounds. The impacts of HTST and UHT methods on various food products are discussed, including the food matrix, preservation parameters and the mechanism of interaction. The ability to modify the processing parameters can allow for the selection of adequate preservation parameters for individual products and better results than other unconventional methods, such as HPP (high-pressure processing) or PEF (pulsed electric field). Based on the cited literature, it can be concluded that pH, titratable acidity and TSS most often experience slight changes. As for the other parameters considered, it is extremely important to choose the right temperature and duration for a specific food matrix.

Carbohydrate composition of cow's milk and plant-based milk alternatives

The prevalence of lactose intolerance is one of the factors driving consumers toward plant-based milk alternatives (PBMA). This study aimed to analyze the carbohydrate profile of cows' milk (regular and lactose-free from both pasteurized and UHT milks; n = 80) and PBMA (n = 60) by HPLC. The study revealed that there was no significant difference in the energy content and total carbohydrate content between regular milk and lactose-free milk. Although milk and PBMA are entirely different food matrices, some PBMA types, as soya and coconut, may have energy contents and total carbohydrate contents comparable to those of milk. Furthermore, the variability observed in total carbohydrate content, as well as in carbohydrate profile, both between PBMA types and within samples of the same type, arises not only from variations in raw materials but also from the number of dilutions of the vegetable extract and the addition of different types and levels of carbohydrates, such as sucrose, fructose, or sorbitol, during PBMA manufacture. Although, milk presents a regular carbohydrate composition, differing solely between presentations (regular/lactose-free), the PBMA differs significantly between types and among the same type, not being for that reason regarded as a milk substitute.

Evaluation of Different Lactic Acid Bacteria as Starter Cultures for Nono—A West African Fermented Dairy Product

Nono is a traditional cultured dairy product consumed across West Africa. In this study, five cultures isolated from Nigerian-produced nono and three purified lactic acid bacteria from the USDA-NRRL were examined for use in preparing nono starter cultures. Isolated cultures were characterized using microbiological and biochemical tests, including 16s rDNA sequencing to identify the genotype. Each isolated strain was cultured and inoculated into UHT milk (1% v/v) and allowed to ferment for 24 h at 25 °C. Fermented products were evaluated for pH, moisture content, water activity, and viscosity, and their descriptive sensory properties were noted. The isolate that resulted in sensory properties most similar to traditional nono was then used as the primary strain for subsequent starter culture blends made with the NRRL cultures. These blends were used for the fermentation of nono and compared with commercial nono samples. Isolates obtained from nono were as follows: Lactobacillus fermentum, Lactobacillus paracasei, and, surprisingly, Lactobacillus rhamnosus, which has not been previously reported as a part of the nono microflora. There was no significant difference in the physical parameters of nono made from the individual indigenous isolates and a similar pattern was observed for the organisms from NRRL, except that their total titratable acidity and viscosities were significantly (p &lt; 0.05) higher than those of the indigenous organisms. Compounded starter made with L. rhamnosus and NRRL cultures was then used to make nono that showed significantly (p &lt; 0.05) different pH and viscosity values than commercially purchased nono, while sensory evaluation showed that nono made from the new starter culture had a high overall consumer acceptance score.

Experimental and molecular dynamics simulation study on the mechanism of β-lactoglobulin self-aggregation induced by ultra-high temperature

Ultra-high temperature (UHT) treatment effectively prevents milk spoilage, yet it can cause protein aggregation, thereby impacting milk stability. β-Lactoglobulin (β-Lg) is a thermally unstable whey protein, but the mechanism of its self-aggregation induced by UHT treatment remains unclear. Herein, experimental approaches and molecular dynamics simulations were performed to elucidate β-Lg aggregation under UHT. The physicochemical properties of the aggregates were initially characterized after different UHT treatments. Size exclusion chromatography and multi-angle static light scattering showed β-Lg aggregates with molecular weights from 20 to 900 kDa and particle sizes from 100 to 350 nm, with bead string and irregular morphologies. Multispectroscopy showed that UHT treatment caused the unfolding of the β-Lg. Molecular dynamics simulations further observed hydrogen bond disruption and β-barrel opening, enhancing the electrostatic interactions and hydrophobicity of β-Lg surfaces, leading to non-covalent aggregation. Furthermore, SDS-PAGE confirmed the involvement of disulfide bonds in aggregate formation, and mass spectrometry identified the disruption of original disulfide bonds under UHT, promoting intermolecular disulfide bonding involving residues Cys119, Cys121, and Cys160. These findings provide a comprehensive understanding of β-Lg aggregation under UHT conditions, which is essential for improving the stability and quality of UHT-treated milk products.

Effect of the Bioprotective Properties of Lactic Acid Bacteria Strains on Quality and Safety of Feta Cheese Stored under Different Conditions.

Lately, the inclusion of additional lactic acid bacteria (LAB) strains to cheeses is becoming more popular since they can affect cheese's nutritional, technological, and sensory properties, as well as increase the product's safety. This work studied the effect of Lactiplantibacillus pentosus L33 and Lactiplantibacillus plantarum L125 free cells and supernatants on feta cheese quality and Listeria monocytogenes fate. In addition, rapid and non-invasive techniques such as Fourier transform infrared (FTIR) and multispectral imaging (MSI) analysis were used to classify the cheese samples based on their sensory attributes. Slices of feta cheese were contaminated with 3 log CFU/g of L. monocytogenes, and then the cheese slices were sprayed with (i) free cells of the two strains of the lactic acid bacteria (LAB) in co-culture (F, ~5 log CFU/g), (ii) supernatant of the LAB co-culture (S) and control (C, UHT milk) or wrapped with Na-alginate edible films containing the pellet (cells, FF) or the supernatant (SF) of the LAB strains. Subsequently, samples were stored in air, in brine, or in vacuum at 4 and 10 °C. During storage, microbiological counts, pH, and water activity (aw) were monitored while sensory assessment was conducted. Also, in every sampling point, spectral data were acquired by means of FTIR and MSI techniques. Results showed that the initial microbial population of Feta was ca. 7.6 log CFU/g and consisted of LAB (>7 log CFU/g) and yeast molds in lower levels, while no Enterobacteriaceae were detected. During aerobic, brine, and vacuum storage for both temperatures, pathogen population was slightly postponed for S and F samples and reached lower levels compared to the C ones. The yeast mold population was slightly delayed in brine and vacuum packaging. For aerobic storage at 4 °C, an elongation in the shelf life of F samples by 4 days was observed compared to C and S samples. At 10 °C, the shelf life of both F and S samples was extended by 13 days compared to C samples. FTIR and MSI analyses provided reliable estimations of feta quality using the PLS-DA method, with total accuracy (%) ranging from 65.26 to 84.31 and 60.43 to 89.12, respectively. In conclusion, the application of bioprotective LAB strains can result in the extension of feta's shelf life and provide a mild antimicrobial action against L. monocytogenes and spoilage microbiota. Furthermore, the findings of this study validate the effectiveness of FTIR and MSI techniques, in tandem with data analytics, for the rapid assessment of the quality of feta samples.

Potential effect of monolaurin and nisin on the growth of three aerobic spore-forming bacteria isolated from Tunisian milk

Antibacterial capacities of monolaurin and nisin on the growth of vegetative cells of three sporeforming bacteria isolated from cow milk collected from Tunisia (Terribacillus aidingensis, Bacillus sporothermodurans and Paenibacillus sp and) were evaluated. Nisin or monolaurin, at different concentrations, can inhibit the growth of three Bacillus. 500 IU/mL and 25 μg/mL corresponded to the minimum inhibitory concentrations of nisin and monolaurin, respectively. The growth of the tested species in the presence of sub-lethal concentrations of monolaurin and nisin was monitored in UHT milk for 7 days at three different temperatures (4°C, 37°C and 25°C). Nisin (250 IU/mL) was able to induce an immediate reduction (after 3 h of incubation at 4°C) of Bacillus species growth (5 log for B. sporothermodurans, 4 log for Paenibacillus sp and 3.2 log for T. aidingensis). Also, monolaurin (25 µg/mL) reduce the growth, at 4°C of B. sporothermodurans by 5 log, Paenibacillus sp by 3 log and T. aidingensis by 4 log, after 3 h of incubation. In the presence of nisin or monolaurin, it can be observed a low reduction in cell growth followed by a rapid regrowth which can attenuate 10 log, at 37°C and 25°C. The obtained data elucidate the potency of nisin and monolaurin, and the application of these antimicrobial agents at low temperatures (4°C) to decontaminate any product from these spoilage bacteria.

Electrical Bioimpedance in Milk Adulterated with Water: Measurement Methodology for Quantification, Influence of Temperature, and Mathematical Modelling

Milk has a high nutritional value and is also one of the most versatile products in the food industry. Unfortunately, fraud involving the product is constant and needs to be combated. This work presents a measurement methodology to perform the electrical impedance analysis in food. The influence of temperature on the measurements has been evaluated through mathematical models specially developed for identifying the fraudulent activity of adding water to milk. The bioimpedance measurements have been performed in a sample container with a four-electrode measurement system and a digital oscilloscope. Samples of 150 mL were analysed, prepared using whole UHT milk adulterated with distilled water in different % by volume (V/V), at temperatures of 16, 28, and 37 °C. The proposed measurement methodology has been validated and showed sensitivity for analysis in milk, revealing the influence of temperature on the impedance values; from the results mathematical models were proposed for investigating adulteration in milk. This work deals with the design of a device capable of measuring bioimpedance in milk with a view to its application in physicochemical analyses. The influence of temperature on the impedance values was also evaluated to propose mathematical models to facilitate analysis with complex factors and matrices.

UHT A2 milks marketed in Brazil: Physicochemical and electrical characterization, rheological behavior and fatty acid profile

UHT A2 Milk offers a consumption alternative for consumers experiencing intestinal discomfort from consuming dairy products. A2 milk, derived from cows with the A2A2 genotype, does not promote the formation of betacasomorphin-7 (BCM-7). However, little is known about the comprehensive composition of this product, as well as its impact on physicochemical and electrical parameters. This study aimed to investigate potential physicochemical and chemical differences between UHT milk with the A2 β-casein genotype and conventional milk without A2 certification, sourced from brands available in the Brazilian market. Therefore, the physicochemical parameters, rheological behavior, electrical impedance, and fatty acid composition were evaluated. The results indicated that A2 milk had higher density, fat, protein, and total solids content compared to UHT milk without A2 certification. Furthermore, it obtained a higher electrical impedance modulus and lower admittance within the analyzed frequency range (1 kHz a 5 MHz). The UHT milk samples showed Newtonian fluid behavior at both temperatures analyzed (10 and 25 °C). Furthermore, the type of UHT milk (with and without A2 certification) did not significantly influence the absolute viscosity of the samples (p > 0.05) across both commercial brands and temperature. Overall, both types of milk had the same composition of fatty acids, with palmitic acid being the major compound. However, C12:0 and C18:1 cis-7 were more abundant in A2 milk. In this sense, the analytical methods used in this study were able to identify differences in macromolecules and compounds within the lipid fraction in the samples investigated. These analytes are suggested as potential identity markers to evaluate the authenticity of UHT bovine containing only beta-casein of the A2 genotype in its composition.

A comprehensive study of the instability of direct-steam-infusion UHT milk: Insights from metabolomics and proteomics

Direct-steam-infusion UHT (dUHT) milk retains more nutrients compared to traditional UHT milk but challenged by age gelation, impacting shelf life. To understand this instability, raw milk, dUHT milk, and age gelation milk were comprehensively studied using metabolomics and proteomics. 2496 metabolites were detected, including amino acids and derivatives, nucleotides and nucleotide derivatives, lipids and fatty acids, and organic acids and derivatives. The most significant change after age gelation was in amino acids, particularly L-lysine, which emerged as the most important indicator related to protein hydrolysis. Proteomics revealed increased calcium-binding proteins, protein fragments, and various proteases in age gelation milk. Ribonuclease A family, cathepsin D, carboxypeptidases, serine/threonine-protein kinase, PLK serine protease 23 contributed to metabolite changes and protein hydrolysis during age gelation. These findings suggested that the hydrolysis of various enzymes altered the overall composition of milk, leading to age gelation, which provided new insights into the instability of dUHT milk.

Insight into protein cross-linking and casein polymerization in pre- and post-hydrolyzed lactose-free UHT milk during long-term storage

During processing and storage of both conventional and lactose-hydrolyzed UHT milk (LHM), aggregation of milk proteins occurs. Protein aggregation can inter alia occur via non-reducible covalent cross-links derived from either Maillard or dehydroalanine (DHA) pathways. To study this further in relation to processing method and lactase enzyme purity, LHM was produced using 3 different lactase preparations, with lactase enzymes added in a dairy setting either before (pre-hydrolysis) or after (post-hydrolysis) UHT treatment. The prepared LHM types were subsequently stored at either 25°C or 35°C for up to one year. Mass spectrometry was used to absolutely quantify the level of furosine, N-ɛ-(carboxymethyl)lysine (CML) and N-ɛ-(carboxyethyl)lysine (CEL), lanthionine (LAN) and lysinoalanine (LAL) in these products using a newly developed method on Triple Q for these processing-induced markers. The results showed higher levels of Maillard related processing markers in pre-hydrolyzed LHM compared with post-hydrolyzed LHM and conventional UHT milk which, on the other hand, contained higher concentrations of DHA-derived cross-links. Proteomics of collected particles from asymmetrical flow field-flow fractionation (AsFlFFF) in combination with gel electrophoresis indicated presence of intra-micellar cross-links during storage, for especially larger particles involving αS1- and αS2-caseins.

Effect of Differences in Protein Levels and Length of Fermentation Time on Physicochemical Characteristics of Caspian Sea Yoghurt Green Tea

Caspian sea inoculum has been widely used for yogurt production, but it is rarely used in making green tea powder (GTP) yoghurt using milk with different protein content. This study aims to determine the changes in the characteristics of GTP yoghurt with Caspian sea inoculum using low fat UHT milk (SLF) or full cream UHT milk (SFC) during the fermentation period at 0 and 16 hours. The results showed that use of different types of UHT milk affected physicochemical characteristics. Fermentation for 16 hours caused a decrease in the pH of the sample to pH 4.3-4.4, but it was negatively correlated with an increase in the acidity. In addition, fermentation resulted increase the value of L* (brightness). The SLF sample has a greener color than the SFC sample. The viscosity of GTP yoghurt increased significantly at 16 hours in SFC and SLF samples. After 16 hours fermentation, the TPC became 4.15 mg GAE/g and 4.45 mg GAE/g with IC50 values ​​of 37.51 g/mL and 23.95 g/mL in SLF and SFC samples. The high protein content in UHT milk affected the high acidity, viscosity, and syneresis values ​​resulting a decrease in the TPC of GTP yoghurt.

Analysis of UHT Diamond Milk Supplier Selection With Analytical Hierarchy Process (AHP) Method cafe Milkyway Coffe &amp; Milk In Berau Regency, East Kalimantan

Every business sector certainly wants consistency in production results, this can be realized through collaboration with raw material providers or suppliers who can ensure the consistent availability of raw materials because the production of raw materials is very vital. Therefore, it is necessary to have a good raw material procurement system and supplier selection so that the production process can run smoothly. Milkyway Cafe is the first pioneering UKM of beverage and food business in Berau Regency, East Kalimantan which has a special characteristic of beverage products made from milk which are liked by many customers, especially teenagers, children, and families. There are problems experienced when selecting suppliers who provide raw materials for UHT milk because there are several factors to consider, namely price, delivery, service, and accuracy of quantities. The sample of the research is the owner of the business that regulates the procurement of UHT milk. The results of the analysis and calculation of the Analytical Hierarchy Process (AHP) using Microsoft Excel stated that the chosen alternative, namely the Kompas with a weight value of 0.46, was superior to the Simpang Utama with a weighted value of 0.34 and the Tops Jaya with a weighted value of 0.20. The main factors that are prioritized in the selection of suppliers at Milkyway are service criteria with a weight value of 0.18, the accuracy of the number of goods with a weight value of 0.15, prices with a weight value of 0.08, and delivery with a weight value of 0.06.

Effect of storage temperature on the physicochemical and sensory properties of regular and lactose-reduced low-fat UHT milk

UHT milk is stable towards spoilage for months, but chemical and enzymatic reactions occur during storage. This study evaluated whether changes over storage (at 4, 20 or 30 °C, for 30–90 d) of regular as well as lactose-reduced UHT milk were discernible by untrained and trained sensory panelists, and which physicochemical parameters they were associated with. Most changes were of low magnitude, such as significant increases in non-protein nitrogen (in both milk types) and lactulose (in regular UHT milk). However, the color of lactose-reduced UHT milk noticeably changed due to browning. Trained panelists evaluated lactose-reduced samples stored at 30 °C as significantly different in color than those stored at lower temperatures and untrained panelists correctly distinguished between fresh and stored lactose-reduced UHT milk in a tetrad-test already after 30 d. Further research is needed to evaluate if consumers detect such changes and therefore dispose of UHT-milk.

A comparison of the quality of UHT milk and its plant-based analogs

The aim of this study was to compare selected physical (density) and physicochemical (color, pH, titratable acidity) properties and the fatty acid profile of dairy UHT milk and its plant-based analogs, i.e., almond, soy, rice, oat, and coconut beverages. Ten products of each type were analyzed in each group. UHT milk was characterized by higher values of color lightness (L*) and titratable acidity than all plant-based milk alternatives, higher yellowness (b*) than rice drink, higher density than almond drink, and higher pH than rice and coconut drinks. In comparison with UHT milk, all plant-based beverages were characterized by higher redness (a*), soy drink was characterized by higher values of b* and chroma (C*), and almond and soy drinks had higher pH values. In the group of non-dairy beverages, the values of b* and C* were highest in soy drink, and the value of a* was highest in almond drink. Almond drink had the highest pH value, and soy and coconut drinks had the highest titratable acidity. Rice drink had higher density than oat, soy and almond drinks. The indicators characterizing the nutritional value of fat were considerably lower in coconut drink and dairy milk than in the remaining products. The values of UFA/SFA, MUFA/SFA, and DFA/OFA ratios and the indicator of nutritional value were highest in rice drink. The PUFA/SFA ratio and the total content of EFAs were highest in soy drink, and the n-6/n-3 PUFA ratio was highest in almond drink.

Exploration of dynamic interaction between β-lactoglobulin and casein micelles during UHT milk process

The protein aggregation induced by UHT treatment shortens the shelf life of UHT milk. However, the mechanism of β-Lg induced casein micelle aggregation remains unclear. Herein, the dynamic interaction between β-Lg and casein micelles during UHT processing was investigated by experimental techniques and molecular dynamics simulations. Results showed that β-Lg decreased the stability of casein micelles, increased their size and zeta potential. Raman and FTIR spectra analysis suggested that hydrogen and disulfide bonds facilitated their interaction. Cryo-TEM showed that the formation of the casein micelle/β-Lg complex involved rigid binding, flexible linking, and severe cross-linking aggregation during UHT processing. SAXS and MST demonstrated β-Lg bound to κ-casein on micelle surfaces with a dissociation constant (Kd) of 3.84 ± 1.14 μm. Molecular docking and dynamic simulations identified the interacting amino acid residues and clarified that electrostatic and van der Waals forces drove the interaction. UHT treatment increased hydrogen bonds and decreased total binding energy. The non-covalent binding promoted the formation of disulfide bonds between β-Lg and casein micelles under heat treatment. Ultimately, it was concluded that non-covalent interaction and disulfide bonding resulted in casein micelle/β-Lg aggregates. These findings provided scientific insights into protein aggregation in UHT milk.