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

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

Short communication: estimation of the financial benefit of using Jersey milk at different inclusion rates for Cheddar cheese production using partial budgeting

Partial budgeting was used to estimate the net benefit of blending Jersey milk in Holstein-Friesian milk for Cheddar cheese production. Jersey milk increases Cheddar cheese yield. However, the cost of Jersey milk is also higher; thus, determining the balance of profitability is necessary, including consideration of seasonal effects. Input variables were based on a pilot plant experiment run from 2012 to 2013 and industry milk and cheese prices during this period. When Jersey milk was used at an increasing rate with Holstein-Friesian milk (25, 50, 75, and 100% Jersey milk), it resulted in an increase of average net profit of 3.41, 6.44, 8.57, and 11.18 pence per kilogram of milk, respectively, and this additional profit was constant throughout the year. Sensitivity analysis showed that the most influential input on additional profit was cheese yield, whereas cheese price and milk price had a small effect. The minimum increase in yield, which was necessary for the use of Jersey milk to be profitable, was 2.63, 7.28, 9.95, and 12.37% at 25, 50, 75, and 100% Jersey milk, respectively. Including Jersey milk did not affect the quantity of whey butter and powder produced. Althoug further research is needed to ascertain the amount of additional profit that would be found on a commercial scale, the results indicate that using Jersey milk for Cheddar cheese making would lead to an improvement in profit for the cheese makers, especially at higher inclusion rates.

Transcriptome analysis for discovering candidate genes involve in embryogenesis in coconut (Cocos nucifera L.) through 454 pyrosequencing

Coconut, Cocos nucifera L. is a major plantation crop, which ensures income for millions of people in the tropical region. Detailed molecular studies on zygotic embryo development would provide valuable clues for the identification of molecular markers to improve somatic embryogenesis. Since there is no ongoing genome project for this species, coconut expressed sequence tags (EST) would be an interesting technique to identify important coconut embryo specific genes as well as other functional genes in different biochemical pathways. The goal of this study was to analyse the ESTs by examining the transcriptome data of the different embryo tissue types together with one somatic tissue. Here, four cDNA libraries from immature embryo, mature embryo, microspore derived embryo and mature leaves were constructed. cDNA was sequenced by the Roche-454 GS-FLX system and assembled into 32621 putative unigenes and 155017 singletons. Of these unigenes, 18651 had significant sequence similarities to non-redundant protein database, from which 16153 were assigned to one or more gene ontology categories. Homologue genes, which are responsible for embryo development such as chitinase, beta-1,3-glucanase, ATP synthase CF0 subunit, thaumatin-like protein and metallothionein-like protein were identified among the embryo EST collection. Of the unigenes, 6694 were mapped into 139 KEGG pathways including carbohydrate metabolism, energy metabolism, lipid metabolism, amino acid metabolism and nucleotide metabolism. This collection of 454-derived EST data generated from different tissue types provides a significant resource for genome wide studies and gene discovery of coconut, a non-model species.

Plenary Lecture 2: Milk and dairy produce and CVD: new perspectives on dairy and cardiovascular health

Cardiovascular diseases (CVD) are the leading cause of mortality and morbidity worldwide. One of the key dietary recommendations for CVD prevention is reduction of saturated fat intake. Yet despite milk and dairy foods contributing on average 27 % of saturated fat intake in the UK diet, evidence from prospective cohort studies does not support a detrimental effect of milk and dairy foods on risk of CVD. This paper provides a brief overview of the role of milk and dairy products in the diets of UK adults, and will summarise the evidence in relation to the effects of milk and dairy consumption on CVD risk factors and mortality. The majority of prospective studies and meta-analyses examining the relationship between milk and dairy product consumption and risk of CVD show that milk and dairy products, excluding butter, are not associated with detrimental effects on CVD mortality or risk biomarkers, that include serum LDL cholesterol. In addition, there is increasing evidence that milk and dairy products are associated with lower blood pressure and arterial stiffness. These apparent benefits of milk and dairy foods have been attributed to their unique nutritional composition, and suggest that the elimination of milk and dairy may not be the optimum strategy for CVD risk reduction.

Manipulation of milk fatty acid composition in lactating cows: opportunities and challenges

Public health policies recommend a population wide decrease in the consumption of saturated fatty acids (SFA) to lower the incidence of cardiovascular and metabolic diseases. In most developed countries, milk and dairy products are the major source of SFA in the human diet. Altering milk fat composition offers the opportunity to lower the consumption of SFA without requiring a change in eating habits. Supplementing the diet of lactating cows with oilseeds, plant oils and marine lipids can be used to replace the SFA in milk fat with monounsaturated fatty acids (MUFA), and to a lesser extent, polyunsaturated fatty acids (PUFA). Due to ruminal metabolism, the decreases in milk SFA are also accompanied by increases in trans fatty acids (TFA), including conjugated isomers. The potential to lower SFA, enrich cis MUFA and PUFA, and alter the abundance and distribution of individual TFA in milk differs according to oil source, form of lipid supplement and degree of oilseed processing, and the influence of other components in the diet. The present review summarises recent evidence on changes in milk fat composition that can be achieved using dietary lipid supplements and highlights the challenges to commercial production of modified milk and dairy products. A meta-analysis on the effects of oilseeds on milk fatty acid composition is also presented.

Quantification of major camel milk proteins by capillary electrophoresis

Proteins from dromedary camel milk (CM) produced in Europe were separated and quantified by capillary electrophoresis (CE). CE analysis showed that camel milk lacks b-lactoglobulin and consists of high concentration of a-lactalbumin (2.01 ± 0.02 mg mL-1), lactoferrin (1.74 ± 0.06 mg mL-1) and serum albumin (0.46 ± 0.01 mg mL-1 ). Among caseins, the concentration of b-casein (12.78 ± 0.92 mg mL-1) was found the highest followed by a-casein (2.89 ± 0.29 mg mL-1) while k-casein represented only minor amount (1.67 ± 0.01 mg mL-1). These results were in agreement with sodium dodecyl sulphatepolyacrylamide gel electrophoresis patterns. Overall, CE offers a quick and reliable method for the determination of major CM proteins, which may be responsible for the many nutritional and health properties of CM.

Can milk proteins be a useful tool in the management of cardiometabolic health? An updated review of human intervention trials

The prevalence of cardiometabolic diseases is a significant public health burden worldwide. Emerging evidence supports the inverse association between greater dairy consumption and reduced risk of cardiometabolic diseases. Dairy proteins may have in important role in the favourable impact of dairy on human health such as blood pressure (BP) control, blood lipid and glucose control. The purpose of this review is to update and critically evaluate the evidence on the impacts of casein and whey protein in relation to metabolic function. Evidence from acute clinical studies assessing postprandial responses to milk protein ingestion suggests benefits on vascular function independent of BP, as well as improvement in glycaemic homeostasis. Chronic interventions have been less conclusive, with some showing benefits and others indicating a lack of improvement in vascular function. During chronic consumption BP appears to be lowered and both dyslipidaemia and hyperglacaemia seems to be controlled. Limited number of trials investigated the effects of dairy proteins on oxidative stress and inflammation. The beneficial changes in cardiometabolic homeostasis are likely mediated through improvements in insulin resistance, however to gain more detailed understanding on the underlying mechanism of milk proteins warrants further research. The incorporation of meals enriched with dairy protein in the habitual diet may result in the beneficial effects on cardiometabolic health. Nevertheless, future well-designed, controlled studies are needed to investigate the relative effects of both casein and whey protein on BP, vascular function, glucose homeostasis and inflammation.