diplomsko delo
Manca Hočevar (Author), Barbara Jeršek (Reviewer), Andreja Čanžek Majhenič (Mentor)

Abstract

Mleko in mlečni izdelki so odličen vir za razvoj mikroorganizmov (MO), tako koristnih, patogenih kot kvarljivih. V diplomskem delu smo ugotavljali njihov vpliv na surovo in pasterizirano mleko, jogurt, kefir, smetano ter surovo maslo. S pregledom literature smo spoznali, da so najpogostejši koristni MO mlečnokislinske bakterije (MKB), med katere spadajo predvsem sevi rodov Lactobacillus, Lactococcus, Leuconostoc, Streptococcus, Enterococcus. Tehnološko najkoristnejša naloga MKB je fermentacija laktoze, ki je pomembna pri izdelavi fermentiranih mlečnih izdelkov. Poleg tehnološko koristnih MKB so pomembni tudi probiotični MO (npr. bifidobakterije), ki so v manjši meri naravno prisotni v surovem mleku. Najpogostejši patogeni MO v mleku in mlečnih izdelkih so Listeria monocytogenes, Salmonella spp., Staphylococcus aureus, Campylobacter spp., Escherischia coli, Enterobacter ter Yersinia enterocolitica, predvsem kot posledica slabega zdravstvenega nadzora krav in osebja. Uživanje takega surovega mleka ali izdelkov iz surovega mleka pa lahko pripelje do izbruhov bolezni. Prisotnost kvarljivcev v mleku in izdelkih je odraz slabe higiene mlekarske opreme, nezadostne toplotne obdelave ter nepazljive in nehigienske predelave surovega mleka. Kvar se kaže v neznačilnem okusu, vonju, barvi, aromi ter prisotnosti neželenih plinov. Pomembni kvarljivci so psihrotrofne bakterije, ki so občutljive za toploto, a izločajo toplotno stabilne proteolitične in lipolitične encime.

Keywords

mleko;mlečni izdelki;mikroorganizmi;bakterije;tehnološko koristni mikroorganizmi;kvarljivi mikroorganizmi;patogeni mikroorganizmi;surovo mleko;pasterizacija;jogurt;kefir;surovo maslo;smetana;

Data

Language: Slovenian
Year of publishing:
Typology: 2.11 - Undergraduate Thesis
Organization: UL BF - Biotechnical Faculty
Publisher: [M. Hočevar]
UDC: 579.67:637.5
COBISS: 104560131 Link will open in a new window
Views: 182
Downloads: 36
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Other data

Secondary language: English
Secondary title: Microorganisms in milk and dairy products
Secondary abstract: Milk and dairy products present an ideal environment for growth of beneficial, pathogenic and spoilage microorganisms (MO). In our thesis, we investigated how these affect raw and pasteurised milk, yoghurt, kefir, cream and butter. By reviewing the literature, we realised that the most common beneficial MO are lactic acid bacteria (LAB), for example Lactobacillus, Lactococcus, Leuconostoc, Streptococcus and Enterococcus. The most technologically important function of LAB is lactose fermentation, which is important in the production of fermented dairy products. Beside technologically important LAB, there are also health beneficial probiotics (for example Bifidobacterium spp.). The most common pathogens in milk and dairy products are Listeria monocytogenes, Salmonella spp., Staphylococcus aureus, Campylobacter spp., Escherichia coli, Enterobacter and Yersinia enterocolitica, mainly as a result of poor health control of cows and staff. However, consumption of such raw milk and products can lead to disease outbreak. The presence of spoilage MO is due to poor hygiene of milking equipment, insufficient heat treatment, and careless and unhygienic processing of raw milk. Spoilage is evident as uncharacteristic taste, smell, colour and aroma. The most common spoilage MO are psychrotropic bacteria, which are heat-sensitive, but they produce proteolytic and lipolytic enzymes.
Secondary keywords: milk;dairy products;microorganisms;bacteria;beneficial microorganisms;spoilage microorganisms;pathogenic microorganisms;raw milk;pasteurization;yogurt;kefir;butter;cream;
Type (COBISS): Bachelor thesis/paper
Study programme: 0
Embargo end date (OpenAIRE): 1970-01-01
Thesis comment: Univ. v Ljubljani, Biotehniška fak., Oddelek za živilstvo
Pages: VIII, 23 f.
ID: 15023661