Liquid Milk Products Research Articles

Destabilization of ultra-instantaneous ultra-high-temperature sterilized milk stored at different temperatures

Ultra-instantaneous UHT (UI-UHT, > 155°C, < 0.1 s) treated milk exhibits higher retention of active protein than regular UHT milk. However, UI-UHT products demonstrate increased susceptibility to destabilization during storage. This study aimed at monitoring the destabilizing process of UI-UHT milk across different storage temperatures and uncovering its potential mechanisms. Compared with regular UHT treatment, ultra-instantaneous treatment markedly accelerated the milk's destabilization process. Aged gel formation occurred after 45 d of storage at 25°C, while creaming and sedimentation were observed after 15 d at 37°C. To elucidate the instability mechanism, measurements of plasmin activity, protein hydrolysis levels, and proteomics of the aged gel were conducted. In UI-UHT milk, plasmin activity, and protein hydrolysis levels significantly increased during storage. Excessive protein hydrolysis at 37°C resulted in sedimentation, while moderate hydrolysis and an increase in protein particle size at 25°C resulted in aged gel formation. Proteomics analysis results indicated that the aged gel from UI-UHT milk contained intact caseins, major whey proteins, and their derived peptides. Furthermore, specific whey proteins including albumin, lactotransferrin, enterotoxin-binding glycoprotein PP20K, and MFGM proteins were identified in the gel. Additionally, MFGM proteins in UI-UHT milk experienced considerable hydrolysis during storage, contributing to fat instability. This study lays a theoretical foundation for optimizing UI-UHT milk storage conditions to enhance the quality of liquid milk products.

Nudging Chinese consumers to embrace sustainable milk consumption: How should information be provided?

AbstractChina's per capita dairy consumption has been far below the intake level recommended by the World Health Organization. Since the dairy industry is a significant contributor to carbon emissions, the recently launched “Double‐Carbon” goals in China may also suppress the supply of dairy products, further reducing Chinese residents' dairy intake. While the notion of sustainable (i.e., nutritious and environmentally friendly) food consumption has recently gained popularity in the policy arena, whether Chinese milk consumers are ready to embrace this notion and what specific measures can effectively promote sustainable milk consumption in China remain unclear. On the basis of a discrete choice experiment, this paper examines how information nudges (i.e., randomly provided messages with different contents and details) may steer Chinese consumers into choosing liquid milk products with attributes that are more nutritious and environmentally friendly. Our analysis, involving 839 consumers randomly selected from Beijing, China, shows that consumers value carbon labels the most, followed by nutrition claims, sustainable production claims, and energy conservation certificates. Meanwhile, nutrition information induces consumers to place higher values on nutrition claims; in contrast, environmental information raises consumers' willingness to choose environmental sustainability‐related attributes. Finally, the concreteness of the information provided strengthens these effects [EconLit Citations: D12, Q01, Q13, Q18].

Safety and quality evaluations of liquid milk and infant formula products in China in 2022

AbstractMilk serves two nutritional functions: it provides nutrition while also maintaining a healthy intestinal microenvironment. Thus, the safety and quality of milk products are critical for consumers' health. To evaluate liquid milk and infant formula products in China, we analyzed nine indices of 294 batches of pasteurized milk (PM), 92 batches of ultra‐high temperature milk (UHT), and 20 batches of infant formula milk powder (IF) collected from 21 provinces in 2022. All PM, UHT, and IF samples were satisfactory concerning aflatoxin M1 contamination, contamination by heavy metals, and residues of veterinary drugs and pesticides. The contents of lactoferrin, α‐lactalbumin, β‐lactoglobulin, furosine, and lactulose in the majority of samples met the group standards. Moreover, the contents of lactoferrin, α‐lactalbumin, and β‐lactoglobulin were higher in PM than in UHT, while furosine and lactulose contents showed the opposite trend. The findings concerning the safety and quality of milk products in China provide important insights to aid consumer preferences for milk products.

Combined treatment of ε-polylysine and thermosonication to inactivate Bacillus cereus and their application in pasteurized milk

At present, most liquid milk products use high-temperature short-time heat treatment (HTST). However, HTST treatment cannot completely inactivate the bacteria in milk, which seriously affects the quality, safety, and shelf life of the product. Therefore, exploring the combined use of HTST and other technologies is of great importance to the production of high-quality pasteurized milk. In this study, we compared thermosonication (TS), ε-Polylysine (ε-PL), ε- PL combined with TS (ε-PL-TS), and HTST to inactivate B. cereus in pasteurized milk. Based on this comparison, we further discussed the inactivation ability and potential mechanism of ε-PL-TS treatment on B. cereus. The experimental result indicated that ε-PL-TS treatment had an obvious inactivation impact on B. cereus. The cell architecture was damaged by ε-PL-TS treatment, causing the leakage of proteins and DNA from the cell. ε-PL-TS treatment caused metabolic disorders by reducing the activities of key enzymes such as succinate dehydrogenase (SDH) (72.5%), malate dehydrogenase (MDH) (70.5%), and ATPase (80.3%). Meanwhile, the activity of CAT and POD decreased by 42.5% and 48.7%, respectively, suggesting that oxidative stress may be involved in the bactericidal mechanism. In addition, the combined treatment effectively inhibits microbial proliferation of pasteurized milk during storage at 4 °C. Therefore, ε-PL-TS treatment can be used as a potential new inactivated microorganism technology that is helpful to obtain high-quality pasteurized milk with a long shelf life.

Effects of different heat treatments on Maillard reaction products and volatile substances of camel milk.

Camel milk has unique compositional, functional and therapeutic properties compared to cow's milk and also contains many protective proteins with anti-cancer, anti-diabetic and anti-bacterial properties. In this experiment, fresh camel milk was heat-treated at different temperatures and times, and the changes in Millard reaction products were analyzed. Meanwhile, headspace-gas chromatography-ion migration spectrometry (HS-GC-IMS), electronic nose and electronic tongue were used to analyze the changes of volatile components in camel milk after different heat treatments. The results showed that the Maillard reaction was more severe with the increase of heat treatment, and the contents of furosine and 5-hydroxymethylfurfural increased significantly when the heat treatment temperature was higher than 120°C. HS-GC-IMS results showed that the contents of aldehydes and ketones increased obviously with the increase of heat treatment degree. The study clarifies the effects of different heat treatment degrees on Maillard reaction degree and flavor of camel milk, which has practical production guidance significance for the research and industrialization of liquid camel milk products.

Overview of packaging materials for Dairy packaging

Regarding milk producing, it is well known that processing and packaging are the two equally important operational phases. Packaging is the last, but definetly not the less important phase. Various automation strategies are constantly being utilized in every phase of processing, packaging and production/use of new packaging materials. The most suitable packaging will provide adequate properties to pack liquid milk and dairy products which have an important role to prolonged product shelf life. Temperature and moisture are important parameters which affect the shelf life of packaged milk and dairy products, due to their effect on the bacterial growth especially in fermented milk products. The aim of this review article is to introduce advantages and disadvantages and principles of packaging methods and materials correlated to shelflife of dairy products.

The Potential Benefits of N2 Gas Flushing Technology for Various Dairy Products: A Sustainable Approach That Proved to Be Multiadvantageous for Preserving the Quality and Safety of Raw Milk During Its Storage

Worldwide, food production systems are confronted with multifaceted challenges. In the context of global climate change, the necessity to feed an expanding population while addressing food insecurity and reducing the tremendous losses and wastage of food places all production steps under considerable pressure. In this context, dairies also face extensive pressure to reduce greenhouse gas emissions, wastewater, and sludge; here, as elsewhere, innovative technological solutions must meet sustainable criteria. To preserve the quality and safety of raw milk during its storage, N2gas flushing technology was devised and implemented at laboratory and pilot plant scales: the treatment proved to be multiadvantageous considering microbiological, biochemical, and technological aspects. The proposed study aims to reconsider the benefits of the patented N2flushing technology, applied at the “raw milk stage” and evaluate the potential advantages that the treatment would confer, in terms of quality and safety aspects, to various dairy products such as liquid milk products, butters, creams, ice creams, and cheeses, including local and traditional dairy products.

Molecular Discrimination between Organic and Conventional Liquid Milk Products in Thailand Using 1H-NMR Metabolomics Approach

The aims of this study were to characterize and compare non-volatile polar metabolite profiles of organic and conventional liquid milk products using a non-targeted proton nuclear magnetic resonance ( 1 H-NMR) metabolomics approach. Pasteurized plain-liquid milk products from 10 different brands available in Thai marketplace were analyzed for their major chemical compositions and 1 H-NMR derived metabolome data. Results demonstrated no specific trend for differentiation between organic and conventional milk samples based on their pH, fat, protein, lactose, and milk solid-not-fat compositions. A total of 45 non-volatile polar metabolites in milk samples were identified by 1 H-NMR technique. The chemometric analysis allowed discrimination between organic and conventional milk samples based on their 1 H-NMR metabolite profiles. Changes in the relative concentration of formate, betaine, dimethyl sulfone, 2-oxoglutarate, creatine, pyruvate, butyrate, proline, acetoacetate, alanine, glycerophosphocholine, carnitine, and hippurate were statistically identified as potential biomarkers accountable for the discrimination between organic and conventional milk samples in this study. Variations of these compounds might be the reflections of animal diets, rumen fermentation, and physiological adaptation of the cows raised in organic dairy farming systems. Our findings provide new insights and support the effectiveness of using a non-targeted 1 H-NMR combined with chemometrics to investigate the molecular authenticity of organic food products.

Levels of Perfluorinated Compounds in Liquid Milk Products in Korea

This study was carried out to monitor the level of 17 perfluorinated compounds (PFCs) present in liquid milk products sold on the Korean market. The liquid milk samples were extracted via liquid-liquid extraction and analyzed by LC-MS/MS. Excellent linearity over the calibration range (r2>0.99), and the limit of quantification of perfluorooctane sulfonate (PFOS) was 0.021 ng/g, and perfluorotetradecanoic acid (PFOA) was 0.057 ng/g. The accuracy was in the range of 72.5-115.3%, and the precision was under 20%. The preprocessing method for this experiment is considered appropriate for analysis of milk samples. The proposed analytical method was applied for the determination of PFCs in 98 liquid milk product samples, and the average content of total PFCs was 0.6576 ng/mL. PFOA and PFOS were detected in most samples, and their levels were less than 0.1 ng/mL, which was lower than those in other studies.

Advances in Atypical FT-IR Milk Screening: Combining Untargeted Spectra Screening and Cluster Algorithms.

Fourier-transform mid-infrared spectrometry is an attractive technology for screening adulterated liquid milk products. So far, studies on how infrared spectroscopy can be used to screen spectra for atypical milk composition have either used targeted methods to test for specific adulterants, or have used untargeted screening methods that do not reveal in what way the spectra are atypical. In this study, we evaluate the potential of combining untargeted screening methods with cluster algorithms to indicate in what way a spectrum is atypical and, if possible, why. We found that a combination of untargeted screening methods and cluster algorithms can reveal meaningful and generalizable categories of atypical milk spectra. We demonstrate that spectral information (e.g., the compositional milk profile) and meta-data associated with their acquisition (e.g., at what date and which instrument) can be used to understand in what way the milk is atypical and how it can be used to form hypotheses about the underlying causes. Thereby, it was indicated that atypical milk screening can serve as a valuable complementary quality assurance tool in routine FTIR milk analysis.

Survey of Aflatoxin M1 in Commercial Liquid Milk Products in China

The objective of this study was to investigate the occurrence of aflatoxin M1 (AFM1) in Chinese liquid milk products. A total of 190 liquid milk samples, including 168 ultrahigh-temperature-treated milk samples and 22 pasteurized milk (PM) samples, were collected in August 2019. A screening assay with the Charm rapid test kit and a confirmation method with high-performance liquid chromatography were used for AFM1 analysis. Nine (4.74%) samples were screened positive, of which 5 (2.11%) samples were confirmed with concentration levels of 0.022 to 0.049 μg/kg. The AFM1 levels confirmed were all below the maximum residue levels set by China, the European Union, the United States, and the Codex Alimentarius Commission. The detection rate of AFM1 in domestic milk samples was 3.39%, while no AFM1 was detected in samples of imported milk. The prevalences of AFM1 detected in three groups of brands were as follows: group I, the major brands of China, 2.70%; group II, the local city domestic brands, 4.55%; and group III, the brands imported into China, 0. The detection rate of AFM1 was significantly higher in PM samples (9.09%) than in ultrahigh-temperature-treated samples (1.19%) (P < 0.05). Although the residue level of AFM1 did not exceed the maximum residue levels in any of the samples, the higher detection rate in local Chinese brands, especially in PM samples, deserves the attention of the Chinese government and consumers.

Determination of A2 β-casein and total β-casein in cow milk and milk powder by capillary zone electrophoresis

β-casein (β-CN) is one of the major casein proteins in cow milk. There are 13 different variants documented for β-CN in cow milk, among which A1 and A2 are the major variants. The separation and quantitation of A2 β-CN are imperative for A2 dairy products. A new capillary zone electrophoresis (CZE) method with UV detection at 214 nm was established for the separation and quantification of the A2 variant and total β-CN content in cow milk and milk powders. The separation of β-CN variants was achieved on bare fused silica capillaries (50 μm×30/40 cm (effective/total length)). The separation buffer was a mixture of 4 mol/L urea, 0.2% (mass fraction) hydroxypropyl methylcellulose, 140 mmol/L citric acid, and 50 mmol/L disodium hydrogen phosphate buffer (pH 2.7). The corrected peak areas and the concentrations of total β-CN and the A2 variant showed good linearity, with correlation coefficients (r2) ranging from 0.9968 to 0.9997. The intra-day precisions for A2 β-CN and total β-CN determination in four samples (two pasteurized milk samples and two milk powder samples) were in the ranges of 2.4%-4.7% and 2.6%-4.8%, respectively. The inter-day precisions for A2 β-CN and total β-CN determination in four samples were in the ranges of 4.0%-6.3% and 3.9%-6.7%, respectively. The recoveries of A2 and total β-CN ranged from 85.5% to 106.4%. With the established CZE method, the A2 β-CN variant and total β-CN protein in liquid and powder bovine milk products could be separated and accurately quantified. By calculating the A2 β-CN content in the total β-CN, the quality of A2 dairy products can be evaluated, and this in turn would aid in the protection of consumer rights.

A Survey of 61 Veterinary Drug Residues in Commercial Liquid Milk Products in China

To investigate the drug residue status in commercial liquid milk products in China, 190 samples, including ultrahigh temperature milk (n = 168) and pasteurized milk (n = 22) samples, were collected in 2019. Milk samples were analyzed for the presence of any of the 61 veterinary drugs in them by using a screening assay combined with an ultraperformance liquid chromatography-tandem mass spectrometry analysis. Ten (5.26%) samples were found positive for β-lactams, tetracyclines, and aminoglycosides, and six (3.16%) samples were confirmed residual for penicillin G (n = 6; 3.16%), tetracycline (n = 1; 0.53%), and oxytetracycline (n = 1; 0.53%), with the maximum concentration of 2.85, 40.64, and 12.35 μg kg-1, respectively. Drug residue detection rate in group II (4.55%; the local city domestic brands) was higher than that in group I (2.70%; the major brands of China) and group III (2.78%; the imported brands into China) and higher in domestic samples (3.39%) than that in imported samples (2.78%), and higher in pasteurized milk samples (9.09%) than in ultrahigh temperature milk samples (2.38%). All drug residue levels were far below the regulated maximum residue limits. However, based on some veterinary drug residues detected in the samples, there is a potential veterinary drug risk in liquid milk products in the Chinese market, and this situation deserves the attention of governments and consumers.

Prevalence of aflatoxin M1 in raw milk and three types of liquid milk products in central-south China

The objective of this study was to survey the prevalence of aflatoxin M1 (AFM1) in raw, pasteurized, extended shelf life (ESL) and UHT milk from central-south China. A total of 734 milk samples, comprising raw milk (133 samples), pasteurized milk (410), ESL milk (93) and UHT milk (98), were obtained between Nov. 01, 2018 and Mar. 31, 2019.The AFM1 concentrations in milk samples were detected by ELISA and confirmed by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Five hundred and ninety samples (80.4%) were positive for AFM1; the mean value was 23.7 ng/L, and the range was 5.1–104.4 ng/L. The percentages of AFM1 positive raw, pasteurized, ESL and UHT milk samples were 75.2, 82.2, 81.7 and 78.6%, respectively. The AFM1 concentration in raw milk was significantly lower (p < 0.05) than that in pasteurized and ESL milk, and the AFM1 level in UHT milk tended to be lower (p < 0.10) than that in pasteurized and ESL milk. The AFM1 levels exceeded the EU legal limit of 50 ng/L in 0, 11.5, 18.3 and 3.1% of raw, pasteurized, ESL and UHT milk samples, respectively. All milk samples tested had levels far below China's legal limit of 500 ng/L. Therefore, the AFM1 content in raw milk and milk products in central-south China does not pose a public health threat, but close attention should nonetheless be paid to milk AFM1, given the high positive rate of 80.4%.

Changes in Milk Protein Interactions and Associated Molecular Modification Resulting from Thermal Treatments and Storage

We investigated protein modifications that occur during short- and long-term storage of raw, pasteurized, and ultra-high-temperature processed (UHT) milks using RE-HPLC and redox proteomics. The RE-HPLC results show that casein dissociation and whey protein/κ-casein association occurred in both pasteurized and UHT milk. The extent of protein interactions was more pronounced in UHT milk after storage. The redox proteomics analyses show that primary structural level protein modifications were not correlated to processing type on the of day processing but did occur and increase during storage. Methionine oxidation was the most significant type of oxidative modification in all samples, particularly in the caseins. Methionine oxidation increased in the UHT-treated milk samples with longer storage times, especially in the micelle-phase proteins, likely due to the increasing exposure of these proteins as they migrated to the serum phase. Glycated and lactosylated early-stage Maillard reaction products were also found after heat treatment, particularly in UHT-treated milk, with the levels of these products maintained and generally increased with increasing storage time. PRACTICAL APPLICATION: Understanding changes in protein modification during heat processing and storage of liquid milk products may help develop a model to predict the quality and shelf-life stability of heat treated milk products.

APLIKASI THEORY OF PLANNED BEHAVIOR DAN ATRIBUT PRODUK TERHADAP KEPUTUSAN PEMBELIAN PRODUK SUSU CAIR DALAM KEMASAN PADA MAHASISWA INDONESIA DAN MALAYSIA

&lt;em&gt;The consumption rate of milk in Indonesia is still lower than other countries in ASEAN, including Malaysia. A geographical difference makes the consumer of packaged milk of both countries have different behavior in purchasing decision. According to the theory of planned behavior, the purchasing decision was formed by intention that is influenced by attitude toward behavior, subjective norm, and perceived behavioral control. Product attribute was considered to influence the purchasing decision, like price, brand, packaging, and quality. The aims of this research are to comprehend the effect of theory of planned behavior and product attribute on purchase decision of packaged liquid milk products towards Indonesian and Malaysian Undergraduate student. The sampling method used is purposive and analysis SEM PLS. The number of respondents is 100 undergraduate student in Indonesia and 100 in Malaysia. The result showed that the significant varibles on TPB for Indonesian students were attitude toward behavior and perceived behavioral control, and for Malaysian students, attitude toward behavior, subjective norm, and perceived behavior control. The significant variable on product attributes for Indonesian student were the brand and product quality, and there was no significant variable for Malaysian student&lt;/em&gt;.

Development of a HPLC method for the simultaneous analysis of riboflavin and other flavin compounds in liquid milk and milk products

A high-performance liquid chromatography method with fluorescence detection was developed for the quantification of riboflavin (RF), flavin mononucleotide (FMN), flavin adenine dinucleotide (FAD) and their photodegradation products, lumichrome (LC) and lumiflavin (LF), in liquid milk and milk products. Both sample preparation and chromatographic separation were studied to avoid acidic conditions that proved to affect flavin stability and degrade FAD into FMN. The sample preparation includes centrifugal skimming and ultrafiltration steps and is suitable for routine application. Linear response was obtained for individual flavins in the respective concentration ranges of interest and relative standard deviation (RSD) was lower than 5%, except for FAD (RSD 11%). The recovery ranged between 80–100%. The proposed method proved to be suitable for assessing flavins in commercial liquid milk and fermented milk products, and for monitoring the degradation of FAD, FMN and RF and the formation of LF and LC in bottled milk exposed to light during shelf storage.

The Contribution of Swaziland Dairy Board on Dairy Farmers’ Productivity: A Case of Mbabane Sub-Region, Swaziland

The Swaziland Dairy Board (SDB) was established under the Act No. 28 of 1968 to promote increased dairy production to satisfy the domestic and export market. Despite numerous efforts of SDB through its dairy policy goals, Swaziland is failing to achieve self-sufficiency in liquid milk production, and can hardly sustain its local demand. Therefore, the study aimed at establishing the contribution of SDB policy goals on smallholder dairy farmers’ productivity. Primary data was collected from 120 dairy farmers through the use of a structured questionnaire in the Mbabane sub-region. The study characterized dairy farmers as mostly male (57%) who are aged above 55 years and married (88%), attained secondary education(48%) with farming experience of 4 years, milking averagely 2 cows per day, and each cow yielding averagely 10 litres and 13 litres per day for non-SDB and SDB members, respectively. The results further revealed that farmers trained by SDB were practicing more of the recommended animal husbandry practices compared to non-SDB farmers. Moreover, the SDB farmer’s milk yields were higher than non-SDB farmers at 10% significant level, although SDB farmers’ milk productivity is still regarded relatively low. Factors influencing productivity of milk among small holder dairy farmers included sex of the farmer, age, dairy sales incomes, number of milking cows, market distance, use of supplementary feed, dairy records keeping and the breeding system. Therefore, local milk production can increase if the stakeholders in the dairy industry can adopt SDB policy strategies, dairy related services and good livestock husbandry practices.

Metabolism fatty acids total lipids in the liquid contents of scars and productive cows indices in the presence in their diet coffee slurry

The biochemical mechanisms of action available in the diet in the summer of coffee sludge on metabolic processes in the body and productive performance of cows are poorly understood. The purpose of the study was to metabolism of nitrogenous compounds in liquid capacious rumen, milk production and composition of milk cows in the presence of the coffee slurry in the diet in the summer. Higher levels of fat obtained by the addition to the diet of cows coffee sludge. Cows fed feed consisting of coffee slurry in an amount of 8 and 16%. Established that the average daily feed of cows in the body, which together with the young grasses and legumes and forage fed coffee sludge reported in 4.2 and 11.2% more neutral detergent and 4.5 and 12.2% acid detergent fiber. Feeding cows coffee sludge results in reduction of nitrogen ammonia and amino nitrogen in their liquid roomy scar regardless of time relative to the start of feeding. Thus, the amount of protein nitrogen in the rumen fluid of cows increased research at the 10th hour from the start of feeding, and general – to 7–10th. As a result of feeding the young grass, fodder and coffee sludge cows increased average daily milk yield. At the same time research in the milk of cows increased protein, fat and lactose. The most pronounced effect on the metabolism of nitrogenous compounds in the rumen of cows and productive performance makes extra feeding cows with young grasses and legumes and forage, coffee slurry in an amount of 16% by weight of feed.

Visual and light scattering spectrometric method for the detection of melamine using uracil 5′-triphosphate sodium modified gold nanoparticles

A highly selective method was presented for colorimetric determination of melamine using uracil 5′-triphosphate sodium modified gold nanoparticles (UTP-Au NPs) in this paper. Specific hydrogen-bonding interaction between uracil base (U) and melamine resulted in the aggregation of AuNPs, displaying variations of localized surface plasmon resonance (LSPR) features such as color change from red to blue and enhanced localized surface plasmon resonance light scattering (LSPR-LS) signals. Accordingly, the concentration of melamine could be quantified based on naked eye or a spectrometric method. This method was simple, inexpensive, environmental friendly and highly selective, which has been successfully used for the detection of melamine in pretreated liquid milk products with high recoveries.