Microbiology in Dairy Processing

Challenges and Opportunities

Palmiro Poltronieri, Palmiro Poltronieri

• Publisher: Wiley-Blackwell
• Year: 2017
• ISBN:
  9781119114987
• Edition: 1
• Topic: Technologie et ingénierie
• Subtopic: Sciences de l'alimentation

An authoritative guide to microbiological solutions to common challenges encountered in the industrial processing of milk and the production of milk products

Microbiology in Dairy Processing offers a comprehensive introduction to the most current knowledge and research in dairy technologies and lactic acid bacteria (LAB) and dairy associated species in the fermentation of dairy products. The text deals with the industrial processing of milk, the problems solved in the industry, and those still affecting the processes. The authors explore culture methods and species selective growth media, to grow, separate, and characterize LAB and dairy associated species, molecular methods for species identification and strains characterization, Next Generation Sequencing for genome characterization, comparative genomics, phenotyping, and current applications in dairy and non-dairy productions.

In addition, Microbiology in Dairy Processing covers the Lactic Acid Bacteria and dairy associated species (the beneficial microorganisms used in food fermentation processes): culture methods, phenotyping, and proven applications in dairy and non-dairy productions. The text also reviews the potential future exploitation of the culture of novel strains with useful traits such as probiotics, fermentation of sugars, metabolites produced, bacteriocins. This important resource:

• Offers solutions both established and novel to the numerous challenges commonly encountered in the industrial processing of milk and the production of milk products
• Takes a highly practical approach, tackling the problems faced in the workplace by dairy technologists
• Covers the whole chain of dairy processing from milk collection and storage though processing and the production of various cheese types

Written for laboratory technicians and researchers, students learning the protocols for LAB isolation and characterisation, Microbiology in Dairy Processing is the authoritative reference for professionals and students.

1
Milk fat components and milk quality

Iolanda Altomonte, Federica Salari and Mina Martini

Department of Veterinary Sciences, University of Pisa, Pisa, Italy

1.1 INTRODUCTION

From a physico‐chemical point of view, milk is an emulsion of lipid globules and a colloidal suspension of protein and mineral aggregates in a solution of carbohydrates (mainly lactose). In Western countries, milk and dairy products, and in general food of animal origin, are often accused of causing adverse health effects, especially with regard their food lipid intake, since lipids have been implicated in several diseases such as obesity, insulin resistance and atherosclerosis (Olofsson et al., 2009). For these reasons, the number of studies on the physical and chemical structure of fat in several edible products of animal origin have increased. Although milk and dairy products contain saturated fatty acids, they also provide specific beneficial components for human health and also lipid components (phospholipids, some individual fatty acids (FAs) and fat‐soluble vitamins) that have a role in health maintenance. In addition, milk is a major source of dietary energy, especially in developing countries, where there is shortage of animal‐source food (FAO, 2013), and in childhood.

Milks of different origins have long been used, and they have been processed to dairy products for their longer shelf life. Due to the wide natural variability from species to species in the proportion of milk macronutrients and to variations along lactation, milk represents a flexible source of nutrients that may be exploited to produce a variety of dairy products.

Ruminant milk is the main source available for humans to use to manufacture dairy products and fermented milk. Besides cow’s milk and milk from other ruminants (such as buffalo, goat and sheep), research on milk from other species is still poorly exploited (FAO, 2013). More recently, equine milks have been suggested for use in children with severe IgE‐mediated cow milk protein allergy (CMPA) (Monti et al., 2007, 2012; Sarti et al., 2016), and local producers have established a niche for the application of donkey products with well‐characterised profile of its constituents (Martini et al., 2014a).

1.1.1 Milk fat globules

Milk lipids are composed of milk fat globules (MFGs) made up of triglycerides enveloped by a biological membrane. MFGs are responsible and/or contribute to some properties and phenomena in milk and dairy products and may affect milk fatty acid composition and the way in which fat is digested (Baars et al., 2016; Huppertz and Kelly, 2006; Martini et al., 2017). For the dairy industry it is of interest that changes in the morphometry of the MFGs lead to changes in milk quality, yields, and ripening and the nutritional quality of cheeses (Martini et al., 2004).

In milk of different species there are MFGs of various sizes, ranging from a diameter smaller than 0.2 µm to a maximum of about 15 µm, with an average diameter that varies as a function of endogenous (species, breed), physiological (parity, stage of lactation), and exogenous factors (feeding) (Martini et al., 2010a).

Different average diameters have been reported in the literature for ruminant species (3.5–5.5 µm for cows; 2.79–4.95 µm for sheep; 2.2 and 2.5–2.8 µm for goats and 2.96–5.0 µm for buffalos) (Table 1.1) (Martini et al., 2016b). However average diameter of globules in equids is considerably lower than other dairy species (about 2 µm in donkey) (Martini et al., 2014b), while regarding human MFGs, larger dimensions have also been found (4 µm) (Lopez and Ménard, 2011).

Table 1.1 Average values in literature for fat content, milk fat globules characteristics and fatty acid composition of milk from different species.

...

		Cow	Buffalo	Goat	Sheep	Donkey	Horse	Human
Fat	%	3.70	8.14	3.90	6.50	0.36	1.48	3.34
Average diameter of the fat globules	µm	3.5–5.5	2.96–5.0	2.2–2.8	2.79–4.95	2	2–3	3.3
SFA	g/100g fat	71.24	65.9	70.42	71.85	55.55	45.18	41.77
MUFA	g/100g fat	25.56	31.4	25.67	26.04	22.21	31.88	38.73
PUFA	g/100g fat	3.20	2.70	4.08	2.10	21.08	22.93	16.96
UFA	g/100g fat	28.76	34.1