Celebrating the milestone in science
Image: Given cheddar’s large share of the UK market, monitoring of changes during maturation is of great commercial importance. Credit: Lidl
This year marks the 80th anniversary of the foundation of the Society of Dairy Technology and the 76th year of the launch of its publications. The first review in the issue covered the characteristics of low-fat whipped cream containing protein-based fat replacers. Some of the most successful additions have been milk proteins, sometimes modified, and their effectiveness in emulsification and foaming is commonly improved by further addition of complex polysaccharides. Both proteins and complex carbohydrates will contribute to higher viscosity in the aqueous phase and reduce drainage. Other animal and vegetable proteins were included in the review.
Maximising the economic returns from whey is an important driver in minimising environmental risks associated with its careless disposal. Whey processing has to consider the range of wheys that may be produced as by-products of cheese production. For example, the higher calcium levels and lower pH in acid whey. Recovery of whey proteins may use membrane filtration and/or ion exchange. The remaining lactose may then be refined or used as a substrate for fermentations, whether just to lactic acid or to create base materials for fine chemical production or biopolymers.
Sustainable milk production systems based on fresh forage and prohibiting silage have been called the Noble Method in Italy. Hay from local mixed grasslands is permitted. This review covers the benefits of the approach in terms of polyunsaturated fatty acid levels and enhanced micronutrients.
Dairy Chemistry
Rubber hoses are widely used in the handling of milk, from lines in milking machines to the unloading of bulk milk tankers. The rubber contains additives such as N-(1,3-dimethyl-N´-phenyl-p-phenelediamine (6PPD), which may migrate from the rubber into the milk passing through the hose. A study indicated that 6PPD migration into milk was limited to the first 10 minutes and that degradation of 6PPD was faster in high moisture liquids.
A study of six bioactive milk proteins indicated that most, except ß-casein AI, were at higher levels in milk from Jersey than Holstein cows. Most of the proteins exhibited seasonal variation and some exhibited geographical variation. Immune protein levels, eg, lactoferrin, correlated with somatic cell counts.
Organic mercury may accumulate in fat and fatty tissue and is extremely toxic. Papain-functionalised gold nanoparticles were exposed to test solutions and their aggregation in the presence of mercury led to a shift in absorption peak from 525 to 575nm. Mercury concentrations of one part per million in milk could be detected.
Membrane filtration
Pasteurised skim milk was concentrated to 20% solids by ultrafiltration then further concentrated by nanofiltration till permeate flux rate declined to 0.1 litre/m2/hour. Higher solids could be achieved by raising the process temperature from 22 to 50°C and increased further by applying hydrodynamic cavitation.
Spray drying
Acidified milk is difficult to spray dry, causing problems with build-up on the spray drier wall. Reconstituted skim milk at 25% solids was acidified with 0.5-3% lactic acid and spray dried using a two-fluid nozzle. Wall deposition increased with lactic acid level and yield increased with drying temperature difference, which also affected particle size, moisture content and water activity. Particle size could also be affected by nozzle airflow, while moisture content and water activity were also related to lactic acid content.
Frozen desserts
A comparison was made between candied orange peel (COP) and orange peel powder (OPP) as additives to a frozen yogurt (25 parts yogurt to 75 parts ice cream base). OPP at 2.5% was preferred to 8% COP and had higher levels of beta-carotene and dietary fibre than the unflavoured control.
Ice cream mixes were produced by heating the ingredients to 65°C for five or 30 minutes and under half or normal atmospheric pressure before freezing without ageing. The five-minute vacuum treatment increased viscosity but reduced overrun and air bubble size. Sensory analysis suggested that the vacuum treatments improved sweetness, milky and creamy perceptions.
Butter
Mistreated butter can suffer from oxidative rancidity and microbial contamination and some plant extracts can increase resistance to oxidation. Addition of a nano emulsion of a Ferulago angulata extract plus metabolites produced by Lactiplantibacillus plantarum subsp. plantarum was found to improve antioxidative and antimicrobial properties, leading to increased shelf life.
Cheese
Many companies have adopted digital marketing to complement their traditional approaches. A study was made of the digital marketing tools employed during the Covid-19 pandemic by companies producing Pecorino Siciliano cheese, which has a protected designation of origin. The conclusion was that the companies overall could improve their digital marketing.
Given cheddar’s large share of the UK market, monitoring of changes during maturation is of great commercial importance. Raman and mid-infrared (MIR) spectroscopy were used to investigate changes in the protein structure of cheddar cheese. MIR data were more sensitive to chemical changes than the Raman data, where the correlation could be improved by focussing on the protein-dominant regions.
