A new structure for the Journal

The International Journal of Dairy Technology, Volume 78, Issue 2, examined India’s milk collection system and Turkish microbiology. Volume 78:2 comprised three reviews, 18 original research papers, two short communications, the abstracts from the Nordic Dairy Congress, one book review and an obituary to Professor Donald Muir. In addition to this, the citation for the award of the Society of Dairy Technology Gold Medal to Andrew Wilbey is available. Readers will notice the move towards structured abstracts of papers, which makes reading the summaries very easy.

Reviews

In the first of three review papers, the milk procurement system in India is addressed by looking at the development, current status and challenges of the milk collection system in that country. The review finds that cohesive strategies encompassing policy reforms, technological integration and capacity building are necessary in order to enhance milk quality and farmer income and ensure the sustainability of India’s dairy sector.

Aflatoxin contamination in the dairy sector was the subject of the second review, and it found that aflatoxin levels in dairy feed remain a persistent hazard in the dairy sector, leading to variable levels of Aflatoxin M₁ in milk and dairy products. While some milk processing techniques can reduce aflatoxin levels, complete elimination while preserving nutritional and sensory quality remains challenging.

Sustainable utilisation of salt whey from cheese manufacture is the final review and it highlights innovative strategies for the use of this by-product. It explores desalination methods, biotechnological applications and circular economy opportunities, offering practical insights to enhance resource efficiency and reduce environmental impacts in the global dairy industry.

Original research: Microbiology

Five papers focus on microbiology in this issue and the first of these concentrates on Salmonella species in milk and dairy products collected in Turkey. Salmonella spp. was detected in 12 of 300 samples collected. All 36 isolates of the species were resistant to at least two antibiotics, with the highest resistance to ampicillin. The study concluded that implementing effective pasteurisation and hazard control measures is crucial to reducing contamination risks and protecting public health.

Somatic cell count (SCC) has long been used as an indicator of mastitis in cattle; more recently differential SCC (DSCC) has been found to be more effective and the Foss method gives rapid results. In sheep the method has not been validated so the next paper determined the cut off value and carried out the validation on three sheep breeds. The results of the Foss DSCC method for sheep milk were comparable to those of the method for bovine milk. For the first time, the Foss DSCC method was validated in sheep milk, and SCC and DSCC cut-off values were determined for three important dairy milk breeds of ewes in Italy. These results will allow the development of further studies to improve mastitis screening and will help in the identification of SCM in flocks.

An evaluation of the spoilage potential of a heat stable protease Bacillus cereus 12-1 in liquid milk found that the protease caused protein hydrolysis in whole milk and skim milk. Additionally it effectively hydrolysed κ-casein and β-casein and caused the release of free amino acids in UHT milk and significantly increased particle size. 

The potential use and sensory attributes of essential oils, such as olive and black seed oils, along with d-amino acids, as antimicrobial additives in Domiati cheese under osmotic stress, were evaluated for controlling methicillin-resistant Staphylococcus aureus. The number of MRSA cells treated with olive and black seed oils and d-tryptophan was significantly reduced in cheese. The natural additives used improved overall acceptability and other sensory attributes of the cheese.

The microencapsulation of probiotic species of Lactobacilli using vibratory extrusion technology and dairy by products is reported. The cell viability of the strains after encapsulation was 8.8 log cfu/mL. Dairy by-products provided significant protective effects for probiotics. The encapsulation improved the survival of the strains against adverse conditions.

Milk composition

A2 milk has been the subject of much discussion over recent years and a study into consumer perceptions with respect to sensory and gastrointestinal attributes was carried out using an online survey. Results showed that A1 milk was more commonly associated with a ‘darker colour’ and ‘strong smell’, while A2 milk was linked to ‘regulated intestines’.

The fatty acid and protein profiles of the colostrum of two Turkish breeds of sheep were analysed in a further study. The resulting profiles showed distinct differences between the two breeds and the authors felt that such differences showed potential for innovation in functional foods and nutraceuticals, particularly for infant nutrition and health-related applications.

In a study to compare the milk fat globule membrane (MFGM) proteins of Chinese Holstein bovine and Guanzhong dairy goat milk, analysis showed that goat MFGM contains unique bioactive proteins and has distinct nutritional properties. Biomarkers were identified which provide novel targets for dairy authentication. 

Cheese and whey

An evaluation of the technological properties of whey protein hydrolysates (WPH) obtained through enzymatic hydrolysis of native and heat-denatured whey protein concentrates found that both enzymatic hydrolysis and heat denaturation play an important role in modulating its functional properties. It was felt that optimising the balance between these processes could help tailor WPH properties for specific food applications, such as heat-stable protein formulations. 

A study of the effects of pre-treating whey protein concentrate (WPC) using trisodium citrate and homogenisation, either individually or combined, to enhance protein transmission during microfiltration is reported. The results demonstrate that treatment of WPC can be used to increase protein permeation during MF, enabling more sustainable processing of value-added whey protein ingredients.

Crossbreeding is used to enhance genetic diversity and improve herd health and fertility. Typically Jersey cows may be cross bred with Holstein Friesians and the impact of these genotypes on processing efficiency and product quality within the cheddar manufacturing process is reported. No practical adverse impacts were detected in cheddar cheese produced from a typical crossbred system. Jersey-Holstein-Friesian and Holstein-Friesian derived cheddar showed no significant differences in processing efficiency, nutrition and quality. The authors found that Jersey-Holstein-Friesian cheese was significantly more yellow, an often favoured sensory quality.

An investigation into the conditions and formation mechanism of whey protein isolate-sodium alginate (WPI–SA) complexes using multispectral techniques and molecular simulations found that WPI exposed more hydrophobic regions for binding with SA. Meanwhile, the foaming and emulsifying properties of the WPI–SA complexes significantly improved and exhibited strong antioxidant properties. These results provided valuable information for applying WPI–SA complexes as stabilisers and texture modifiers in the food industry.

Ice cream

Oleogels have been studied as replacers for trans and saturated fats in ice cream production. In the next reported investigation, chitosan based oleogels were used and the effect of method of incorporation was studied. The incorporation after pasteurisation was found to be the optimal strategy for chitosan-based oleogel in ice cream.

The perception of creaminess in ice cream was explored through a combination of dynamic and static sensory methods, finding that the factors that reduced the perception of creaminess included the iciness, coldness and hardness. The study also found that the factors that drive the perception of creaminess include cream flavour, thickness, mouth coating, viscosity, smoothness and melting time.

Yogurt

With the title “Residual antibiotics in milk at maximum residual limits affects yogurt fermentation but not yogurt rheology” the purpose of the study is clear. The detail is that the study found that antibiotic-added milks had longer fermentation times compared with a control sample, but this varied according to antibiotic type. The study also found that the presence of antibiotic had no effect on the number of Streptococcus thermophilus, but Lactobacillus delbrueckii subsp. bulgaricus counts were lower than those of the control sample regardless of the antibiotic type.

Another yogurt based study explores the feasibility of using orange peel powder (OPP) as a fat replacer in frozen yogurt. Results revealed that a formulation containing 2% milk fat and 2.5% OPP was most acceptable, offering improved nutritional value, desirable viscosity and consumer acceptability, while enabling the development of dietetic frozen yogurt.

Ambient stored yogurt sometimes exhibits reduced viscosity and the editors choice article for Issue 2 of the Journal discusses the development of a simple and rapid method for separating colloids and microbial cells from yogurt, and a universal method for extracting microbial genomic DNA which enabled rapid analysis of the causes. This analysis indicated that the viscosity reduction in yogurt was likely caused by Geotrichum candidum contamination in the granulated sugar.

CIP

An artificial fouling model and a modular cleaning-in-place (CIP) test bed were developed for evaluating sustainable CIP strategies and fouling removal during milk pasteurisation for cheese production. The study showed that both increased milk protein: fat ratio and fouling development times lead to greater levels of residual fouling on stainless steel surfaces as used in dairy processing plants. The platform developed will enable further development of sustainable CIP alternatives for use in dairy processing.

Short communication

In the first of two short communications, the use of milk permeate as an inducer of lactose crystallisation in sweetened condensed milk was investigated and found that effective crystallisation control similar to pure lactose was achieved. It was felt that repurposing a common dairy by-product promotes sustainable production.

The resistance of Lentilactobacillus parabuchneri, which is the main producer of histamine in cheeses, to the temperatures used in in-vat pasteurisation of milk is examined in the second short communication. Findings showed that the species resisted the traditional 63ºC for 30 minutes and thus pasteurisation would not prevent the accumulation of histamine in cheeses. However, a 5°C increase in pasteurisation temperature eliminated them from milk, which would really help to prevent the accumulation of histamine but recognised that this temperature would have consequences on the curd formation.