Bioactive peptides in dairy products

Bioactive peptides are hydrolysates with specific amino acid sequences that exert a positive physiological influence on the body. They are inert within the native protein, but once cleaved from the native protein by microbial or added enzymes and/or gastrointestinal enzymes during the digestive process, they apply their beneficial traits. Dairy products, particularly fermented products, are potential sources of bioactive peptides: several of them possess extra‐nutritional physiological functions that qualify them to be classified under the ‘Functional Foods’ label. Biological peptides in milk, the methods of their generation and their prevalence in dairy products are reviewed along with the reported health benefits and safety aspects.     

Enhancing the sweetening power of lactose by enzymatic modification in the reformulation of dairy products

Lactose solutions of up to 50% (w/v) were incubated with lactases and glucose isomerases for subsequent implementation in dairy product samples to enhance sweetness. A degree of hydrolysis of >90% and of isomerisation of 50% were attainable. The sensory sweetening power of lactose in solutions of up to 50% (w/v) can be enhanced 2–3 times. Based on sensory experiments, application of this bi‐enzymatic system in yoghurt and pudding samples allowed for a 10–20% (w/w) reduction in the total sugar content, whilst retaining equal sweetness. The growth of yoghurt starter cultures was not affected, yet furosine formation more than doubled in high heated, enzyme‐modified milk.     

The use of carbon dioxide in the processing and packaging of milk and dairy products: A review

The upswing in consumer demand for fresh and high quality preservative‐free foods has led to the development of modified atmosphere packaging (MAP). Increasingly, MAP is being used with high carbon dioxide (CO₂) concentration as well as CO₂/N₂ gas mixes. Modified atmosphere packaging or ‘gas flushing’ as it is also known is an increasingly popular technique used to extend the shelf life (both quality and safety) of a number of dairy products. Carbon dioxide is an active constituent of MAP, naturally present in freshly drawn raw milk. Addition of CO₂ to raw milk or flushing the package headspace has proved to be a simple and cost‐effective method, depending upon the initial microbiological quality of the food product. Carbon dioxide addition through MAP or direct injection as an economically affordable shelf life extension strategy is used commercially worldwide for some dairy products. The development of food packaging machines with integrated gas flushing capabilities and the supply of ‘food grade’ gases allow dairy foods manufacturers to enhance the quality of their products. This review presents a broad spectrum of current research and the current trends with respect to CO₂ as a natural microbial hurdle with special focus on its precise mechanism and its role in quality improvement of dairy products.     

Effect of combination of essential oils on physicochemical and sensorial attributes of burfi in comparison with individual essential oil and BHA

The study investigated the addition of essential oils (EO) of tumeric, ginger and cardamon (as sources of natural antioxidants ) to burfie, an Indian heat desiccated dairy dessert. Essential oil incorporation significantly (P < 0.05) increased antioxidant activity of the product. Samples with a combination of EOs had a higher antioxidant activity than with addition of individual EOs, but antioxidant activity was less (P < 0.05) than samples with addition of butylated hydroxyanisole (BHA). The addition of EOs had no significant (P > 0.05) effect on instrumental colour, textural attributes and composition of the burfi samples, but flavour was significantly affected. Clustering revealed the sample with added BHA had the best attributes followed by the sample with addition of a combination of all the EOs. The combination of EOs significantly (P < 0.05) delayed the growth of the native microbiota in the burfi.     

Survey of aflatoxin M1 in milk and dairy products consumed in Burdur,Turkey

The aim of this study was to investigate the occurrence of aflatoxin M₁ (AFM₁) in dairy product samples in Burdur city. A total of 315 samples of dairy products were collected during 2008. Of the 315 samples analysed, AFM₁ in 246 samples (78.1%) was found to range from 5.5 to 800 ng/kg. In addition, AFM₁ levels of 16 raw milk, two pasteurised milk, only one milk powder and three white cheese samples were above the Turkish Food Codex. It is concluded that the occurrence of AFM₁ in dairy products may be considered as a possible hazard for public health.     

Polycyclic aromatic hydrocarbons in milk and dairy products

Polycyclic aromatic hydrocarbons (PAHs) are a group of organic compounds with a structure consisting of carbon and hydrogen atoms that have more than two fused aromatic rings. Most PAHs have carcinogenic effects on animal or humans and induce various cancers. Polycyclic aromatic hydrocarbons are a consequence of environmental pollutants, imperfect burning or pyrolysis of organic substances during industrial processing. Additionally, foods can be contaminated during their processing and preparation through different heat treatments. This review highlights the formation, occurrence and health impacts of PAHs in milk and milk products, and analytical technique used for their determination in dairy products.     

Food safety management systems (FSMS) in the dairy industry: A review

Food safety management systems in the industry have been designed and established over the last four decades with several revisions. The dairy industry soon realised the need for proactive procedures hence implementing HACCP (Hazard Analysis and Critical Control Points) for ensuring that safe dairy products would reach the consumers. This article reviews the food safety management systems as well as the relevant EC Regulations that are currently implemented by the dairy industry. The need for rigorous controls in the dairy industry is also highlighted.     

Use of ozone in the dairy industry: A review

Ozone treatment is a cost‐effective and eco‐friendly food‐processing technology. It has successfully been used for the removal of milk residues and biofilm‐forming bacteria from stainless steel surfaces and in milk processing, including fluid milk, powdered milk products and cheese. Ozonation has been shown to prevent mould growth on cheese and inactivate airborne moulds in cheese ripening and storage facilities. Ozone treatment has also been found to be a promising method for reducing the concentrations of pollutants in dairy wastewaters.     

Matrix effects of milk,dairy factory wastewater and soil water on the determination of disinfection by‐products and para‐cresol using solid‐phase microextraction

Assessing pollutant concentrations can be hampered by the complex matrices found in the dairy supply/processing chain. Matrix effects were examined using solid‐phase microextraction (SPME) used to sample haloacetic acid methyl esters (HAAMe) and para‐cresol. In general, HAAMe were more difficult to detect with a polydimethylsiloxane fibre than with carboxen–polydimethylsiloxane fibre. Headspace sampling generally provided better detection of HAAMe than direct immersion with the reverse true for para‐cresol. For para‐cresol, equivalent ratios up to 18.8 were detected. Other compounds detected included sulphides, VOC's, phenols and indoles. For milk samples, most compounds collected by SPME were found using direct immersion.     

The influence of milk with different compositions on the bioavailability of blackberry polyphenols in model sports nutrition beverages

This study aimed to determine whether the fat and protein content in dairy-fruit blends prepared using full-fat, semi-skimmed, skimmed or high-protein milk in combination with freeze-dried blackberry puree influenced the bioaccessibility and bioavailability of blackberry polyphenols and organic acids. Samples were subjected to in vitro digestion, after which bioavailability was analysed with a Caco-2 cell model. The addition of puree to milk resulted in the formation of protein aggregates, which partially protected anthocyanins during digestion. Milk fat may have increased the bioaccessibility of anthocyanins while reducing permeability through the Caco-2 cells, leading to a lower bioavailability in tested samples.     

Detection of aflatoxin M1 in milk and dairy products consumed in Adana, Turkey

A total of 70 dairy products consisting of 20 sterilized milk, 10 butter, 20 white cheese and 20 Kashar cheese samples were analysed for aflatoxin M₁ (AFM₁) by enzyme-linked immunosorbent assay (ELISA). The detection limit was 5 ng/L for milk and 25 ng/kg for butter, white cheese and Kashar cheese. Of the 70 dairy products analysed, AFM₁ in 49 samples (70%) was found to range from 10 to 388 ng/kg. Moreover, AFM₁ levels in three samples of milk, two samples of butter, one sample of white cheese and one sample of Kashar cheese were found to be higher than the Turkish legal limits.     

Dioxins and furans in cow milk and dairy products: A review of the scientific literature

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) are a group of persistent organic pollutants with well-known toxic effects and potential carcinogenicity. Human exposure to PCDD/Fs is mainly through food, including dairy products. The scientific information on the concentrations of PCDD/Fs in milk and dairy products is here reviewed. It also includes the intake of PCDD/Fs through the consumption of these products. PCDD/Fs concentrations in milk and dairy products are currently decreasing. A similar trend is also noted for their contributions to the total dietary intake of PCDD/Fs. No significant health risks due to exposure to PCDD/Fs through the consumption of dairy products are expected.     

Best use for milk – A review. II – Effect of physiological,husbandry and seasonal factors on the physicochemical properties of bovine milk

Part two of this review evaluates the impact of physiological, husbandry and seasonal factors on the physicochemical properties of raw bovine milk and on products manufactured from it. For producers of dairy products, there are opportunities to select the most appropriate feeding regimes for producing raw milk which is optimal for their products, as well as understanding what are the best products to be made from milk produced at different times of the year. For these reasons, the concept of ‘best use’ for milk will become an exciting and profitable area for study.     

Studies on iodine content in daily diets and selected dairy products

Poland's people have moderate – and in seaside areas mild – degrees of severity of iodine deficiency. A national program has been introduced for obligatory iodine prophylaxis and includes the iodination of household salt to the extent of 30 ±10 mg KI/kg. In order to assess the extent of iodine consumption, analytical studies were carried out on iodine content in average Polish diets. Taking into account the fact that milk formulae are frequently the basic source of iodine for infants, studies were performed on the iodine content in selected dairy products, mainly infant formulae. Iodine concentrations in samples were determined in duplicate by radioactive neutron activation analysis (RNAA). The iodine content in Polish diets without added iodinated kitchen salt was low and insufficient to provide the Polish RDA for this element. The results of the analytical investigations of the daily diets showed higher iodine content in comparison to theoretical calculations. The theoretical values accounted for 71–85% of the analytical ones. Study of iodine content in infant formula demonstrated differences between the analytically determined iodine content in products and that declared by producers. Received: 22 November 1999     

Milking and milk processing: traditional technologies in the yak farming system of the Qinghai-Tibetan Plateau, China

Yak milk and its products are widely consumed by local herders and are regarded as the resources of economic income by the households on the Qinghai-Tibetan Plateau. Yak raisers have developed their own milking skills and milk-processing technologies through a long history of yak keeping. All of these traditional skills and technologies have their own characteristics. In this paper, the methods and procedures of milking and milk processing in yak farming systems are reviewed.     

Different effects of the methods of administering lactoferrin,IGF-1 and IgG from bovine colostrum to rabbits based on the cytokine communication network

Lactoferrin, IGF-1 and IgG are three well-known bioactive proteins found in bovine colostrum. We studied the effects of these three active ingredients on the levels of eight cytokines in serum and on the cellular communication networks in vivo by oral administration, intraperitoneal injection and intravenous injection. The results suggested that bioactive ingredients, especially biomacromolecules, can induce different effects, even opposite effects, on the immune system depending on the route of administration. These effects are related to both the functions of the bioactive ingredient in vivo and to its specific receptor binding in the gastrointestinal mucosa that activates different signalling pathways.     

Nanoliposomes coencapsulating curcumin and vitamin D3 produced by hydration of proliposomes: Effects of the phospholipid composition in the physicochemical characteristics of vesicles and after incorporation in yoghurts

Nanoliposomes coencapsulating curcumin and vitamin D₃ (VD3) using different compositions of purified and unpurified lecithins were produced by hydration of proliposomes and characterised over 15 days of storage. The dispersions were incorporated to pineapple yoghurts produced in laboratory‐scale, which were also characterised. Results showed that curcumin and vitamin D₃ were retained in the nanovesicles up to 86.1% and 94.1%, respectively. Most of the parameters assessed for the yoghurt samples were within the limits required by the Brazilian legislation and the Codex Alimentarius. Finally, the enriched product was well accepted by the panellists with the purchase intention ranging from 53 to 75%.     

Marketing trends and future challenges: A review of dairy industry in Saudi Arabia

This paper reviews the challenges facing the Saudi Arabian dairy industry dominated by a few companies engaged in aggressive price war strategies. The key players and the main drivers for milk production and consumption are discussed in detail. The latest developments in the ‘Saudisation’ policy and ‘Nitaqat’ scheme have also affected the quality of the labour force in the industry. The paper concludes that although the future prospects are promising, smaller milk‐producing companies might not survive unless they adopt alternate strategies. The latest push for job replacement with the domestic labour will also create difficulties for dairy firms to produce high quality products at a sustaining labour cost.     

Psychrotrophs in dairy products: Their effects and their control

Health concerns and technological effects of psychrotrophic bacteria in dairy products are reviewed, as well as methods to control their presence and development. The various Gram‐negative and Gram‐positive psychrotrophic species are listed and, with respect to pathogenic psychrotrophs, emphasis is given on Listeria monocytogenes, Yersinia enterocolytica, and Bacillus cereus. The influence of psychrotrophic bacteria on the quality of raw milk, pasteurized and UHT milks, butter, ice cream, cheese, and powders is examined. Public health considerations of Listeria monocytogenes, Yersinia enterocolytica, and Bacillus cereus of these various dairy products are also presented. Methods that can be used to eliminate or control the development of psychrotropic bacteria include low or high temperatures, chemicals, gases, the lactoperoxidase system, lactic acid bacteria, microfiltration, bactofugation, lactoferrin‐related proteins, sanitation, flavors, and naturally occurring spore germinants.