우유위생 제주대학교 수의과대학예방수의학교실
연도별젖소사육현황 ( 단위 : 천두, 천가구 ; 자료 : 국립농산물품질관리원가축통계 ) 젖소두당산유량 ( 단위 : kg/ 년 ; 자료 : 낙농편람, 농협중앙회젖소개량부 ) 연도별원유수급현황 ( 단위 : 톤 ; 자료 : 낙농편람 )
[1] 우유의영양적인가치 - 거의완전한식품 (most nearly complete food). - 소화율은거의 100% [2] 우유의건강증진효과 1. 영양소가많다. 2. 소화, 흡수가잘된다 ( 예외, 유당 Lactose). 2. 균형된영양을공급. 3. 위의건강을증진.(zwitterion, 양 ( 극 ) 성이온 ) 4. 장내유산균의발육왕성, 유해미생물의성장억제 [3] 우유위생의의의및중요성 여러전염병의매개체역할 1. 영양분풍부 => 미생물의증식 => 부패용이. 2. 병원균함유용이, 거의모든병원균증식용이 3. 주로생식하는식품 4. 처리과정을위생적으로하기에어려움이많다.
유제품의제조과정
Terminology 고형분 (solid matter) : 우유에서수분을뺀것 무지고형분 (solid-not-fat) : 고형분중에서유지방을제거한부분 크림 (cream) : 우유의지방층 탈지유 (skim milk) : 지방을제거한나머지부분 전유 (whole milk) : 지방을전혀제거하지않은우유 커드 (curd) : 전유, 탈지유에산또는응유효소를첨가했을때생성되는응고물 (casein 및 fat) 유청 (whey, milk serum) : 커드를제거한나머지의반투명한황록색의수용액
Gross composition of milk of various breeds Body Wt. Yield Fat Protein Lactose Ash Total solid (kg) (kg) (%) (%) (%) (%) (%) Holstein 640 7360 3.54 3.29 4.68 0.72 12.16 Brown Swiss 640 6100 3.99 3.64 4.94 0.74 13.08 Ayrshire 520 5760 3.95 3.48 4.60 0.72 12.77 Guernsey 500 5270 4.72 3.75 4.71 0.76 14.04 Jersey 430 5060 5.13 3.98 4.83 0.77 14.42 Shorthorn 530 5370 4.00 3.32 4.89 0.73 12.90 Composition of Milk from Different Mammalian Species (per 100 g fresh milk) Protein (g) Fat (g) CHO (g) Energy (kcal) Cow 3.2 3.7 4.6 66 Human 1.1 4.2 7.0 72 Water Buffalo 4.1 9.0 4.8 118 Goat 2.9 3.8 4.7 67 Donkey 1.9 0.6 6.1 38 Elephant 4.0 5.0 5.3 85 Monkey, rhesus 1.6 4.0 7.0 73 Mouse 9.0 13.1 3.0 171 Whale 10.9 42.3 1.3 443 Seal 10.2 49.4 0.1 502
Muscle-like cells surrounding each alveolus perform this duty during milking
Milk Proteins proteose 란? peptone 란?
Casein micelles 케이신 (casein) 인산칼슘과복합물 (Ca-phosphocaseinate or Ca-caseinate phosphate complex) 형성 교질상태 (colloid suspension) 로분산 유백색 탈지유의 ph 를 20 에서 4.6 침전 모든포유동물의젖에만들어있는특수한단백질 alpha S 1 -, alpha S 2 -, beta-, kappa-casein 열에비교적안정 130, 수분 응고, 침전 산패응고의원리 : 산을가하면케이신복합물의칼슘과일부의인은유청으로유리 casein 이응고, 침전
유청단백질 (whey) : 20 에서 ph 4.6 으로조절하여 casein 을침전시킨나머지 α-lactalbumin : 묽은산으로응고되지않으며, 총우유단백질의 2-5% β-lactoglobulin : 유청단백질의주성분, 총단백질의 7-12%. 70 에서응고 혈청알부민 : 혈액으로부터이행되는단백질로총우유단백질의 0.7-1.3% 면역글로불린 : IgG 를가장많이함유 IgE, A, M 함유함 총우유단백질의 1.9-3.3% 초유의총단백질의 85-90% Proteose, peptone ph 4.6에서열에안정, 12% TCA에침전 정상유에서총질소량의 3% 정도임 Β-casein의일부 fragment (protein->proteose->peptone) peptone: ammonium sulfate에침전 x 비단백태질소화합물 가용성의질소화합물 정상유에서총질소량의 5% 정도
Milk Fat 유지방구 (milk fat globules) 유탁 (emulsion) 상태로존재 1 ml 에 2-4 x 10 9 개의지방구존재 온도가지나치게높을때에는크림라인소실, 크림분리에는 32 가적합. 65 이상 지방구덩어리가부셔져분산. 균질화우유 (homogenized milk) : 75 에서 1500lb 의압력하에분무 미세한입자 영구적인유탁액
유지방의조성및성질 Saturated fatty acids myristic, palmitic, and stearic make up 2/3 of milk fatty acids. Unsaturated fatty acid Oleic acid is the most abundant ( one double bond ) 주로중성지방 : Olein, palmitin, stearin 등 지방분해취, 패지취 (rancid odor) 낙산 (butyric acid) 을함유하므로 지방산화취 : 산소, 광선, 열, 구리와접촉 산화 유지방은황색 => 카로틴과엽황소등의색소
Milk Sugar, Lactose 젖에만들어있는특유한당, 우유의감미 정상함량 : 4.4-5.2% 유방염젖 현저히낮다. 설탕과포도당보다난용성 : 10 에서 10%, 100 에서약 40% 170 갈색락토캐라멜을형성. 유산발효균 유산생성 C 12 H 22 O 11. H 2 O Glucose + Galactose CH 3. CHOH. COOH( 유산 ) (0.25-0.3% 에달하면우유의산미 ) (0.8-1.0% 에이르면유산균의증식이정지 )
Vitamins 비타민 A : 유지방에풍부, 사료중의 Vit A, 청초중의 carotene 색소의함량에따라변화. 비타민 B 1 (thiamine) : 광선에안정 열에의해파괴됨. 비타민 B 2 (riboflavin) : 유청이특이한황록색원인. 알카리에불안정하나산에안정 62 에서 1 시간가열해도파괴되지않음. 비타민 B 6 (pyridoxine) : 광선에쉽게파괴되나열에안정. 비타민 C (ascorbic acid) : 산화, 가열, 오래저장 쉽게파괴 우유의저온살균시많이감소 비타민 D : 자외선조사된효모를섭취 우유자체자외선조사 우유에농축된간유첨가 자외선을조사한 ergosterol 첨가 젖소자체에자외선을조사시증가. 비타민 D 우유 : 우유매쿼터당 400 단위첨가 비타민 E : 항불임성비타민 성주기에따라영향, 초유에 2.5-7 배많다. The vitamin content of fresh milk (per liter) Vitamins Amount A (ug RE) 400 D (IU) 40 E (ug) 1000 K (ug) 50 B 1 (ug) 450 B 2 (ug) 1750 Niacin (ug) 900 B 6 (ug) 500 Pantothenic acid (ug) 3500 Biotin (ug) 35 Folic acid (ug) 55 B 12 (ug) 4.5 C (mg) 20
Milk Enzymes Milk contains both indigenous and exogenous enzymes. 산화환원효소 (oxidation-reduction enzyme) Catalase : 혼입세균에의해생성되며 H 2 O 2 분해 - 모유는우유보다 5-6배더 H 2 O 2 분해 Peroxidase : 우유를 80 에서가열시파괴 환원효소 (reduction enzyme) : 혼입세균에의해생성 => 위생검사에이용 The most significant group are the hydrolases( 가수분해효소 ) Lipoprotein lipase : splits fats into glycerol and free fatty acids. is found mainly in the plasma in association with casein micelles. Plasmin : splits proteins. Plasmin attacks both ß-casein and alpha(s2)-casein. Alkaline phosphatase : splits specific phosphoric acid esters into phosphoric acid and the related alcohols. destroyed by minimum pasteurization temperatures(61.7 30 분 : 96% 파괴, 62.8 30 분 100% 파괴 ), therefore, a phosphatase test can be done to ensure proper pasteurization. Galactase, Amylase : * 교과서의 galactase 해설은오류로판단됨!!!
기타우유성분 무기물 (inorganic substance): 회분 0.7% Ca, K, Na, P 등다량함유 철분은약 0.00024% 정도로아주미량 구리와망간도극미량이함유 색소 (pigment) 락토크롬 (lactochrome) : 우유의색소를총칭. Carotene, xanthophyll 색소가유지방에포함 계절과사료에따라영향 세포성분 상피세포, 백혈구, 세균, 효모, 곰팡이등. 우유매 ml중백혈구가 500,000개이상 유방염의증세. Gas성분 : 산소 질소, 탄산가스 ( 처음부터우유에존재 ) 면역항체 : 초유를먹음으로써모체면역을얻음.
우유의특성 외관 백색의불투명한액체 casein의 colloid 유지방의황색 carotene과 xanthophyll 유청의황록색 riboflavin 향미 젖당, 염류, 유지방. 초유, 비유말기의우유, 유방염및소화불량의우유 다소쓴맛 우유의오취 우체, 분뇨축사의취기를흡수 수소이온농도 신선우유 : 20 에서평균 ph 6.7 (6.6-6.8) 초유 : ph 6.0, 유방염 ph 상승하여 7.0 이상 온도상승시 ph 저하 칼슘염의용해도저하가관계 산도 (acidity) 신선우유산도 : 0.135-0.175% 범위 산도가 0.25% 가되면 85 o C 에서응고 0.56-0.58% 가되면실온에서응고 초유의산도는정상유의약 3 배 우유의응고 (coagulation of milk) : 산, 알콜, rennet, 가열 (casein 관여 ) 초유, 유산이생긴우유 : 비등점이하의온도에서응고 rennin( 송아지 4위의점막에존재 ) 비중 (specific gravity) : 유지방함량에영향 정상 :15 o C에서 1.027-1.035 ( 평균 1.032) 결빙점 (freezing point) -0.5-0.61. 염류와젖당이관계 가수검사에응용 젖당과염류 : 유성분중가장함량변이가적으므로.. 비등점 (boiling point) : 용해되어있는용질에좌우 1 기압시비등점은 100.55 농축시비등점. 점도 (viscosity) 온도에반비례 케이신, 유지방, 알부민에영향 탈지, 가수에의해 초유, 비유말기유, 젖소의질병, 유방손상시. 표면장력 (surface tension) 0.7-0.8 ( 물의표면장력을 1 로할때 ) 밀도 (density) : 빙점에서최대밀도를나타냄. 굴절률 (refractive index) : 1.3470-1.3515 유청성분의영향, 단백질및유지방은관계가없다.
생리적이상유 Abnormal Milk Colostrum 분만후 4-5 일간생리적으로분비 기능 농도짙고갈색을띤황색, 맛이불쾌. 고형분, 단백질, 회분량이많고젖당은적다. 열에대해잘응고, 강한산성반응. Immunoglobulin 함량이특히많으며,. 10 fold more vitamin A than milk. 3 fold more vitamin D than milk. 10 to 17 fold more iron than milk. higher Ca, P, Mg, Cl, and lower K than milk. higher levels of oligosaccharides than milk. higher proportion of glycosylated k-casein than milk. 어미소의면역항체전달. 비타민 A 는송아지발육에특히중요. 항체의흡수는대부분분만후 24 시간내 ( 항체는태반을통과않는다 ).
The process of macromolecular absorption is initially high at the first suckling, then declines gradually. Intestinal closure to uptake of macromolecules has occurred when no more intact macromolecules can be absorbed. Intestinal closure is a continual, gradual process that starts immediately after birth and proceeds until there is no longer transport of macromolecules. Time of closure is the time after birth when macromolecules (including immunoglobulins) can no longer pass from the intestinal lumen, through the intestinal cell and into the neonate's vascular system. Closure is complete in the calf by about 24 hr after birth, in the piglet at about 36 to 48 hr, in the foal at about 24 to 48 hr, in cats and dogs at about 24 to 48 h.
초유의유조성의변동
염미우유 (salty milk) 지나치게짠맛 비유말기, 유방내병변 Or, 과량인산염류나식염투여시 점조유 (ropy milk) 세균에의한이상발효에기인 점조성이증가. 주원인균 : Alkaligenes viscolactis, Streptococcus, Lactobacillus 등 고미유 (bitter milk) 착유당시이미고미 특수한사료 (wormwood, cabbage) 급여 착유후시간이경과한후고미 세균 (Streptococcus faecalis 등 ) 에의하여단백질이분해 펩톤형성 검화유 (soapy milk) 어취와비누같은맛 세균의작용에기인 착색유 (coloured milk) 적색유 우유에피혼입 : 탄저등의전염병, 약물중독또는유방염등 영균 (Serratia marcescens) 등이관여. 청색유 : 영균 : 유즙표면에적반형성 Brevibacterium erythrogenes: 우유전체가적색 기타세균 : 적색침전대생성 푸른색소를형성하는균 Pseudomonas synxantha 의증식에기인. 황색유 : Staphylococci, Microccocci Pseudomonas synxantha 등이증식.
성분규격상의이상유 ( 부정유 ) 탈지 (skimming) 유지의전부또는일부분을제거 영양가치의저하 검사법 : 유지방량의측정. 가수 (watering) 우유에물을섞은것 검사법 : 비중검사, 초산유청비중측정법, 테트라유청비중측정법, 동유청법, 크라이오스코프법 알칼리첨가 산패한우유에탄산소다또는중탄산소다를첨가 검사법 : 힐거법, 속슬렛-사이버법또는로졸산법 방부제 (antiseptic) boric acid, 붕사, salicylic acid, 안식향산, 치아염소산염, 과산화수소, 포르말린 모든나라에서방부제사용금지.
병적이상유 유방염우유 Staphylococcus aureus: 살균공정에서균체가사멸되나 enterotoxin은우유중에이행 식중독발생의원인 Streptococcus spp, E. Coli, Actinomyces, 등 감소 지방 무지고형분, α-casein,β-casein,α-lactalbumin, β-lactalbumin lactose 산도, K, Ca 증가 serum albumin, immunoglobulin Cl, Na, 전기전도도, ph 체세포 이등유 ( 알코올불안정유 ) 알코올침전시험에서양성반응 젖소의신진대사장애에기인 이온화된칼슘함량이많아지기때문 경제적손실.
Changes in Milk Composition and Quality Mastitis results in several changes in the composition of milk which can be used in mastitis detection, but which also affect the quality and value of milk. lactose - synthesis of lactose is decreased. casein - proteolysis by activated plasminogen (plasmin) from the blood, proteolytic enzymes from leukocytes and bacteria, leads to poor curdling, lowered cheese yield, altered texture of cultured products, production of peptides, bitter taste. This is particularly important if the producer is being paid a premium for milk quality. milk fat - milk fat globule membranes are susceptible to the action of lipase enzymes, resulting in breakdown of triglycerides, oxidation of fatty acids, and off-flavors. Na+, Cl-, K+ - electrical potential across the apical membrane is disrupted. Tight junctions between epithelial cells are weakened, resulting in increased milk Na+. This is the basis of the electrical conductivity methods of detecting mastitis.. Polymorphonuclear neutrophils (PMN) - also called somatic cells (SC) in the milk. Mastitis causes chemotaxis of the cells into the tissue and disruption of epithelial tight junctions. Associated logarithmically with the decrease in milk production. This is the basis of many mastitis detection methods.. albumin, immunoglobulins, bicarbonate (in part determines milk ph) - all enter the milk via disrupted tight junctional complexes. Increased concentrations of these components also have been used as the basis for various mastitis detection methods.
원유중의미생물
원유의미생물오염원 젖소 유우체, 유방, 피모 : Micrococci, Streptococci, Staphylococci, Coliforms 등 젖소의타액, 콧물 사람 : 착유부, 우유취급인의손, 손의창상부, 타액, 콧물등 환경 축사내의공기, 먼지, 설치류, 곤충등 사료, 건초, 퇴비, 젖소의분뇨 우유용기및기구 : Micrococci, Streptococci, Bacilli 등 물 (Pseudomonas, Coliforms), 얼음 사람의의류 원유의미생물오염경로 생체내오염 : 경구혹은유두공을통한침입후 유방내로전파, 정착증식 ( 결핵, 브루셀라, 탄저, 살모넬라등 ). 생체외오염 착유중 : 착유기의청결상태가위생적인원유생산과직결. 착유후 : 접촉하는기구류의세척및소독이불완전한경우.
원유중미생물의종류 (1) Psychrophilic (cold-loving) bacteria grow well at 0 with an optimum temperature about 12 15 and maximum below 20. Psychrotrophic (cold-tolerant) bacteria are mesophilic strains that can multiply at commercial refrigeration temperatures with an optimum temperature about 20 30. Mesophilic bacteria has a minimum temperature about 10, and generally an optimum of 30 35 and maximum at about 50. Without doubt, this is the most common range for bacterial growth. Approximately 90 % of all bacteria can grow in this temperature interval. Thermophilic (heat-loving) bacteria have their optimum growth temperatures at 55 65. Minimum temperature about 37 and maximum around 70 C. The psychrotrophic bacteria are of particular interest to the dairy industry, because microbiological activity in farm milk and market milk usually takes place at a temperature of 7 C or below.
원유중미생물의종류 (1) 내열성세균 (thermoduric bacteria) Microbacterium lacticum 과미생물포자들은살균처리에도생존 Streptococci, Lactobacilli, Corynebacterium 은 60 o C 20 분처리시생존 (63 o C 30 분처리시 1% 이하생존 ) 호냉성세균 (psychrophilic bacteria)=> 저온성균 (psychrotrophic) 30 부근이최적생장온도, 10 이하에서증식 Pseudomonas( 가장많이분리 ), Alcaligenes, Flavobacterium, Enterobacter, Coliform 등 효소 (lipase, proteinase) 분비 유지방, 단백질분해 풍미와질저하. 치즈의수율을저하시킴 원유내의내열세균및저온성세균종류
원유중미생물의종류 (2) Coliform group E. coli, Enterobacter 원유의중요한부패세균 유방표면과우유취급기구가주요오염원 killed by HTST treatment (their presence after treatment is indicative of contamination) 유방염원인균 Streptococcus agalactiae, Str. uberis, Str. dysgalactiae, Sta. aureus, E.coli 원유의체세포수및혈액성분증가 우유분비량과성분은감소 세균수 : 유방염초기 (10,000/ml), 임상형 (1000 만 /ml) 유방염진단법 : strip-cup test, CMT(califonia massage test) 법, 체세포검사법. 병원성미생물 (Pathogenic Microorganisms in Milk) : The following bacterial pathogens are still of concern today in raw milk and other dairy products. Bacillus cereus Listeria monocytogenes Yersinia enterocolitica Salmonella spp. Escherichia coli O157:H7 Campylobacter jejuni 유산균 (Lactic acid bacteria) : ferment lactose to lactic acid. Lactococci ( 유산구균 ) L. delbrueckii subsp. lactis (Streptococcus lactis ) Lactococcus lactis subsp. cremoris (Streptococcus cremoris) Lactobacilli ( 유산간균 ) 기타 L actobacillus casei, L.delbrueckii subsp. lactis (L. lactis), L. delbrueckii subsp. bulgaricus (Lactobacillus bulgaricus) Leuconostoc : Leu. mesenteroides, Leu. cremoris Homofermentative 균 : 유산만생산하는균 Heterofementative 균 : 유산, 초산, 지방산, 알콜, 글리세린, 탄산가스등을생산 Yeast Molds Virus
미생물에의한원유의변화
산패 (souring) 산도증가 ( 유산의농도 0.5% 이상 ). 25 부근의실온에보관 잘발생 가열시응고 Lactococcus lactis, Lactobacillus, Micrococcus, Strepococcus 등 가스생성 : 유산균과경쟁, 대량으로오염되며 CO 2 와 H 2 생성 (Coliform bacteria) 단백질분해 저온에저장시, 열처리로유산균이사멸시, 생성된산이곰팡이나효모등에의하여중화시 생성된 peptide 에의해쓴맛 Micrococcus, Streptiococcus, Bacillus cereus 등 점조유 (ropy milk) 우유, 크림, 유청등에서발생할수있는점조현상 ( 끈끈이현상, ropiness) 시유와크림에서일어나는중요한변패현상. Alcaligens viscolactis, Coliform bacteria, Enterobacter aerogenes 등 기타원유의변패 : Pseudomonas, Proteus, Alcaligernes, Bacilli, Micrococci, Clostridia 에의해지방이산화되거나분해되어변질.
원유중병원균 젖소유래병원균 결핵균 : 우형결핵균 (Mycobacterium bovis), 인형결핵균 (Mycobacterium tuberculosis) 브루셀라균 (Br.abortus, Br. melitensis, Br. suis) : 유방에병변부가없어도젖에는병균이배설 탄저균 (Bacillus anthracis) : 우유분비가갑자기정지되므로젖으로균이배설되지는않음 살모넬라균 (Salmonella dublin) : 사람의식품감염의원인 연쇄상구균 (Streptococcus) : 유방염의중요한원인 (Str.agalatctiae, Str.dysgalactiae, Str.uberis) 포도상구균 (Staphylococcus auaeus) : 유방염의원인균이며우유중에증식하여 enterotoxin을형성 포도상구균성장독소중독 캠필로박터균 (Camphylobacter) : C. jejuni, C. coli는사람의위장염의원인균 Q열리케차 : Coxiella burnetii에의한인수공통전염병으로 62.8 에서 30분간또는 71.7 에서 15초간가열함으로써완전히파괴 구제역바이러스 : 저온살균에의해파괴 우두, 가성우두, 백시니아 (Vaccinia) : 발진성전염병으로우유보다는주로접촉에의해사람에게전염됨
사람유래병원균 인형결핵균 (Mycobacterium tuberculosis) : 결핵환자로부터결핵균의오염 장티푸스균, 파라티푸스균 : 생유보다살균유에서쉽게증식 ( 유산균증식에의한억제 ) 생유보다살균유오염시공중보건상위험. 살모넬라균 : 사람에있어살모넬라증의불현성감염또는보균자로인해우유가오염. 이질균및아메바이질균 : Shigella에의한세균성이질 (bacillary dysentery) 과아메바성이질 (amoebic dysentery) 연쇄상구균 : 성홍열, 편도선염, 특히손에화농소를가진착유부, 우유취급인, 요리사에해오염. 포도상구균 : 포도상구균에의한엔테로톡신중독 디프테리아균 : 우유중 Corynebacterium diphtheria 균은반드시사람에게서유래됨 간염바이러스 : 대변으로오염된음료수또는우유등의공통매개체에의해유행성으로발생.
환경유래병원균 살모넬라균 : 축사에사는설치류와절족동물도원인 보툴리누스균 (Clostridium botulinum) Exotoxin을생성하며치명율이높은식중독원인균 37 에서독소형성이가장왕성하나 8% 이상의식염, 50% 이상의설탕함유, ph4.5이하의물질에서독소생성못함. 리스테리아균 (Listeria monocytogenes) 뇌막염, 유산, 패혈증등을주증으로함 우유및유가공품에이한식중독발생 식품위생학적인면에서주요관심. 세레우스균 (Bacillus cereus) 토양에널리분포 식품및물을통해오염 살균유에서증식부패야기 Enterotoxin을산생하나열에약함 (60 o C에서 5분불활성화 )
우유매개성전염병의역학적특성 Holomiantic outbreak, 공동매개체유행병 ) 전염병또는중독증등이음료수나식품등의공통매개체에의하여폭발적으로여러사람에게발생할때이를말한다. holomiantic 발생곡선 (p.623 그림 25-2) 환자발생분포와우유배달분포의일치 사회경제수준과환자발생과의관계 병원균의분리가능성 우유오염의원인제거와환자발생의감소
원유중에혼입되는유해물질 미생물학적유해물질 : 이화학적유독물질 : 방사능에의한오염 ( 180 Ba, 137 Cs, 131 I 등 ). 화학성유독물질 항생물질 : 과민증과알레르기반응유발, 균교대증의발현, 내성균의출현 잔류농약 : 주로유기염소계농약인 β-bhc, DDT가문제시됨 Aflatoxin : 가장독성이강하며간에발암성. 중금속 구리 : 우유의산화유발 구토 비소 : 농약의사용에의해유즙에이행. Milk allergy: 성인보다유아에많다. Lactose 분해효소인 lactase 결핍에의한설사 Estrogen : 우유중존재가능하나실제적인위험성은없다.
원유의위생적생산 낙농장의환경위생 : 운동장및우사청결및소독철저, 우사환기와채광 젖소의건강 : 위생적인원유생산을위한필수요소 젖소의몸체및유방의청결관리 ( 손질, 유방과유구털깎기 ). 건강유지 유두소독 (chlohexidin(0.5%) 또는 iodine(0.5-1.0%) 으로유두침지 ). 착유부및우유취급인의건강 위생적착유 : 전착유 : 첫유즙을손으로 3-4회짜버린다 (10만 CFU/ml까지세균이오염 ). 옥시토신분비 : 1분이내시작-> 3~4분간왕성히분비 4~5분이내착유완료요!! ( 과착유주의 ) 착유기의철저한세척및소독 : 최저 40, 10-20분정도세척후, 차아염소산 (HOCl) 으로소독 원유의위생적보존 : 착유직후의원유중에는일정시간동안세균의증식이억제되나최소한 2시간이내에 5 이하로냉각되어야한다. ( 냉각기세척도 ) 연중세균수 1등급을유지하기위해서는유방염소여부, 세균수증가의원인파악및대처 원유처리실위생
The effect of the let-down reflex gradually fades away as the oxytocin is diluted and decomposed in the bloodstream, disappearing after 5 8 minutes. Milking should therefore be completed within this period of time.
The phases of machine milking. a Teat cup liner
Milk yield, milking duration, milk flow rate, and certain characteristics of the milk are recorded during milking. In addition, data on cow movements, time of milking and time of concentrate feeding may also be available. Milk leaving the milking station can be divided into different categories and being collected separately from the normal milk. The categories can be: 1 Treated cow 2 Freshly calved cow (colostrum) 3 Cow with less than one milking in the last 24 hours 4 A cow which, although healthy, has cell counts above a certain level The fresh milk is forwarded to a buffer tank for cooling before being pumped to the storage tank.
Fig. 1.19 Bacteria growth at 4 C in raw milk.
기말시험예상문제 : 다음의글을번역하라. In former times, milk was delivered to the dairy twice a day, morning and evening. In those days the dairy was close to the farm. But as dairies became larger and fewer, their areas of collection increased and the average distance from farm to processing increased. This meant longer intervals between collections. Collection on alternate days is common practice today in most of the large dairy countries with modern milk production. Collection every three or even four days is not entirely unknown. Milk should preferably be handled in a closed system, to minimise the risk of contamination. It must be cooled to 4 C as soon as it is produced and then kept at that temperature until processed. All equipment coming into contact with milk must be cleaned and disinfected. Quality problems may arise if the intervals between collections are too long. Certain types of micro-organisms, known as psychrotrophic, can grow and reproduce below +7 C. They occur mainly in soil and water. Therefore, it is important that water used for cleaning is of high bacteriological quality. Psychrotrophic bacteria will grow in raw milk stored at 4 C. After an acclimatization period of 48 72 hours, growth goes into an intense logarithmic phase This results in breakdown of both fat and protein of the milk. This might be an important reason for off-flavours that may jeopardise the quality of products made from the milk. This phenomenon must be taken into account in the planning of collection schedules.
우유처리장의위생관리 유용기구의세척및소독 물세척 (39-46 ) 세제세척 (46-49 로강하게 ) 헹굼 ( 뜨거운물, ph 4.0-5.0 by 인산혹은구연산 ) 배수와건조 관내세척 미지근한물 알칼리세척제 산성세척제 200 ppm 농도의염소용액으로소독. 시간, 온도, 세척제의농도및물리적작용의 4 요소에의해결정. 세척제 : 알칼리세제, 산성세제, 중성세제, 복합세제 소독제 환기시설 : 온도, 습도의조절과밀접한관계 용수관리 : 공공상수도또는그와동등한수질 유해동물및해풍관리 : 방충망을설치 우유처리장종업원의위생관리 개인위생 위생설비 위생교육
우유의살균 저온살균 보온법 : 62.8, 30 분. 고온단시간법 (HTST): 71.7, 15초. 우유자체에는최소한영향 혼입할수있는병원균은모두살균 North's curve : cream line 손상없이결핵균파괴 (Coxiella burnetii ) 가내열성이가장높다 ) 지방, 설탕의함량이높은유제품은 5 더 Vitamin C 20-50% 감소 우유속의세균 90% 이상감소 phosphatase 불활화
열처리가우유에미치는영향
초고온멸균법 ( 상업적으로멸균된우유 ) 130-150, 최소 1 초이상 1 개월이상저장이가능. 멸균효과시험 : Clostridium sporogenes 나 Bacillus coagulans 의아포 β-lactoglobulin 의변성 가열취 2-3 일저장시소실. Phosphatase: 최초불활화, 저장중다시활성화. 비타민 A, D, B2, pantothenic acid, nicotic acid, linolic acid 와같은다가불포화지방산의일부가소실. There are no changes in the nutritional value of fat, lactose and mineral salts, but there are marginal changes in the nutritional value of the proteins and vitamins. Fig. 9.4 Limiting lines for destruction of spores and effects on milk. The values within brackets (30 C and 55 C) express the optimal growth temperatures of the vital types of corresponding spore forming microorganisms. Source: Kessler
Advantages of UHT High quality: The D and Z values are higher for quality factors than microorganisms. The reduction in process time due to higher temperature (UHTST) and the minimal come-up and cool-down time leads to a higher quality product. Long shelf life: Greater than 6 months, without refrigeration, can be expected. Packaging size: Processing conditions are independent of container size, thus allowing for the filling of large containers for food-service or sale to food manufacturers (aseptic fruit purees in stainless steel totes). Cheaper packaging: Both cost of package and storage and transportation costs; laminated packaging allows for use of extensive graphics D-value or decimal reduction time: The D-value, which denotes the decimal reduction time, is the time required at a specific temperature and under specified conditions to reduce a microbial population by one decimal. The decimal reduction time is dependent on the temperature, the type of microorganism and the composition of the medium containing the microorganism. ( 예. 100 에서 1/10 로감소하는데필요한시간이 50 분이었다면?) Z-value: The Z-value is the increase or decrease in temperature required to reduce or increase the decimal reduction time by one decimal. It is a measure of the change in death rate with a change in temperature. ( 예. D-value 를 1/10 로감소하는데필요한온도상승값, 120 에서 5 분이었다면?) F-value: 균이모두사멸하는데걸리는시간
Standardisation The purpose of standardisation is to give the milk a defined, guaranteed fat content. The level varies considerably from one country to another. Common values are 1,5 % for low-fat milk 3 % for regular-grade milk, but fat contents as low as 0,1 and 0,5 % also occur. Homogenisation The purpose of homogenisation is to disintegrate or finely distribute the fat globules in the milk, in order to reduce creaming. Homogenisation may be total or partial. Partial homogenisation is a more economical solution, because a smaller homogeniser can be used. Shelf life of pasteurised milk The shelf life of pasteurised milk is always dependent on the quality of the raw milk. Naturally, it is also most important that production conditions are technically and hygienically optimised, and that the plant is properly managed. When produced from raw milk of sufficiently high quality and under good technical and hygienic conditions, ordinary pasteurised milk should have a shelf life of 8 10 days at 5 7 C in an unopened package. The shelf life can however be drastically shortened if the raw milk is contaminated with micro-organisms such as species of Pseudomonas that form heat-resistant enzyme systems (lipases and proteases), and/or with heat-resistant bacilli such as Bacillus cereus and Bacillus subtilis which survive pasteurisation in the spore state.
우리나라의원유위생관리제도 원유검사기준 ** 일반기준 어떠한약제도첨가되어서는안됨 우유와양유는동일장소에서수유 ( 유처리 ) 해서는안되 혼입되어서도안되 원유검사구분및실시요령 집유전에각 1 회이상실시 원유의냉각온도는 5 이하로유지 검사성적이 60 점미만 3 일간납유금지 불합격된원유는납유금지를할경우검사결과및납유금지기간을통보 원유위생검사업무를신속, 정확히수행해야함 품목별기준 --------------------------------------------------------------------------------------------- 원유생산양유시유멸균우유 --------------------------------------------------------------------------------------------- 관능검사적합 체세포수 75 만 /ml 이하 (SPC) 100만 /ml이하 100만 /ml이하 4만 /ml 이하 음성 대장군균 (ml) 10/ml 이하 음성 포스파타제시험 음성 (LTLH) 무지유고형분 8.0% 이상 8.0% 이상 유지방분 3.0% 이상 3.0% 이상 진애검사 2.0mg 이하 비중 (15 ) 1.028-1.034 좌동 좌동 좌동 산도 ( 이하 ) 저지종 0.20% 0.20% 0.18% 0.18% 기타 0.18% 알콜시험적합 ---------------------------------------------------------------------------------------- SPC: 30, 72 시간
우유및유제품의검사
집유전검사 관능검사 취각검사 : 원유냉각기의뚜껑을열고이취유무판단 시각검사 : 유백색, 균일한조직, 이물혼입등관찰 밝고냄새가없는장소에서우유를충분히교반한후깨끗한시험관에 10 ml 정도의시료 조직의결함 : 지방이분리되어버터화된것 점성이강해실같은조직으로된것 단백질이응고된것 심하게빙결된것 이물질이혼입된것. 풍미의결함 : 잡초취, 불결취, 우체취, 우사취, 쓴맛, 노후한맛, 가열취, 중화취, 금속취, 산미취, 동물지방취, 치즈취, 기타발효취, 약재취, 연기취, 석유및휘발유취, 양파취, 마늘취, 파취, 사일레지취등 알코올검사 가열에대한안정성 ( 신선도 ) 을확인하기위함 산패가진행되어우유무기물평형이좋지못한우유, 초유, 말기유, 응유효소가존재하는우유, 유방염유등을검출할수있음 70% 에틸알코올 10-15 o C 에서원유시료 2 ml 과 70% 에탄올동량혼합 4-5 초후응집여부관찰 비중측정 가수, 유지, 기타부정유검출 축산물가공처리법기준 : 1.028-1.034 200 ml 정도, 비중계, 1-3 분간정치 보정표를사용, 15 에서의수치로환산 진애검사 Sediment disc 상의이물 ( 털, 곤충, 짚, 사료, 흙, 모래 ) 의유무, 수량 진애검사기 (sediment tester) 에소정의진애시험용여과지를부착하여시료 500 ml을여과한후농림부장관이지정한표준판 ( 농림부고시제 1998-34 호관련 ) 과비교
실험실검사 지방측정 Gerber, Babcock, Rose-gÖtllieb 법 자동탁도측정법 Milkotester, Anritsu Milk checker Phosphatase 시험 : 저온살균완전성여부 가열살균에생유혼입여부 산도측정 신선도검사법 중화적정법 : 0.1N NaOH, 유산 % 를산출 Resazurin 시험 : Resazurin( 적자색 ) 의환원 간접적으로우유중세균수를추정 세균수검사 SPC( 표준한천평판 ) 법 체세포수검사 직접현미경검사, Coulter counter, Fossomatic 및 Somacount 허용농도 : 75 만개 /ml 이하. 대표적인체세포 : 백혈구, 상피세포 TTC 시험 : 세균발육억제물질 ( 항생제 ) 잔류량을검출 판정 : 양성 ( 유백색 ), 의양성 ( 복숭아색 ), 음성 ( 적색, 방부제함유안된것 ) 우유중의생균수 (SPC) 위생상태직접반영 ( 유우의위생상태, 착유system의청결, 유방염 ) 1. 우군중유방염우의비율 2. 우군중비유후기우비율 3. 착유인의위생 4. 소와착유기의위생 5. 착유꼭지의상태 6. 착유기펌프의밀봉상태 우유중의체세포 (SCC) 일반적으로불현성유방염의지표 1. 원유의 1차오염의지표 2. 정상적인상피세포 3. 감염시나타나는염증성백혈구등모든세포 4. 유방의감염으로염증 생균수와체세포숫자는불가분의상관관계!! LPC (Laboratory Pasteurized Counts) 1. 저온살균후살아남은균수 (750 이상이면유가감소, 50/ml까지허용 ) 2. 주로불량한기구세척등에기인 3. 유방염에의한것이아님. CC (Coliform Counts) 1. 750 이상이면유가감소 2. 50/ml까지허용 3. 우체의불결 4. Milking wet
Relationship between herd SCC, percent quarters infected and milk production losses per cow Herd SCC Quarters infected ( %) Daily milk Loss (lb) 200.000 6-500,000 16 3.3 1,000,000 32 9.0 1,500,000 48 14.6
If your boss comes to you and says: There will be no salary increases for this year..there are no bonuses either All overtime has been cancelled No expenses will be paid... And there will be no additional healthcare! 올해봉급인상없고 보너스도없고잔업수당도취소됐고 수당도없고추가의료보험도없다! What will your reaction be? 당신의반응은?.!!