QUALITY OF ORGANICALLY PRODUCED MILK

Transcription

1 QUALITY OF ORGANICALLY PRODUCED MILK Dr hab. Ewa Rembiałkowska, prof. SGGW Organic Foodstuffs Division Faculty of Human Nutrition and Consumer Sciences

2 INTRODUCTION Milk is one of the most important nutritional sources, especially in the nutrition of children. Milk and milk products contain biologically active substances, playing an important role in prevention of civilisation diseases, such as atherosclerosis, hypertension, corpulence and diabetes. Recently milk consumption in developed countries has fallen, mainly because of several studies suggesting that milk consumption may increase the risk of suffering from certain health problems.

3 THE MAIN FACTORS AFFECTING COMPOSITION AND PROPERTIES OF MILK Genetic factors Environmental factors Physiological factors Fennema, 1996

4 GENETIC FACTORS SPECIES Different mammals produce milk varying widely in composition. BREED Cow breeds are predominately the result of selection by man, obtained according to the intended use and local conditions. This has led to a wide variability in milk yield and composition. However, the strongly directed selection over the last 100 years has decreased the variation in milk composition between typical dairy breeds. INDIVIDUAL Variation in milk composition among individual cows of one breed may be greater than among breeds. Fennema, 1996

5 PHYSIOLOGICAL FACTORS STAGE OF LACTATION This is the most important physiological variable. However it is difficult to separate this effect from that of other variables such as feeding regimen and grazing. AGE OF COW Most of the milk components decrease slightly in concentration with increasing age of the cow. ESTRUS AND GESTATION Both of them do not have a great effect on milk composition, but they do have on milk yield. Fennema, 1996

6 ENVIRONMENTAL FACTORS FEED The major factor affecting the fat content of milk and especially fat composition. CLIMATE Climate has little effect on milk composition unless it is extreme, causing heat stress. All other kinds of stress, exhaustion and housing are associated mostly with a small effect. METHOD OF MILKING Affects the milk composition strongly in several ways. The shorter the time elapsed after the previous milking, the lower the milk yield and the higher the fat content will be. Hence, evening milking usually results in a higher fat content than morning milking, the differences amounting to 25% fat. During milking the fat content of milk increases (from 1% to 10%), but the differences vary markedly among cows. Incomplete milking thus can decrease the fat content of milking. Short time intervals between milking increase the susceptibility of milk to lipolysis. Fennema, 1996

7 BIOACTIVE COMPONENTS IN MILK

8 PROTEINS Casein is the predominant phosphoprotein that accounts for nearly 80% of proteins in cow milk. An attractive property of the casein molecule is its ability to form a gel or clot in the stomach. The clot is able to provide a sustained slow release of amino acids into the blood stream, sometimes lasting for several hours. This provides better nitrogen retention and utilization by the body.

9 FAT All fats consist of fatty acids bonded to a backbone structure glycerol. Different fatty acids are composed of different numbers of carbon and hydrogen atoms. Fatty acids have long unbranched chain, which is either saturated or unsaturated - saturated fatty acids account for 75% of the total fatty acids in milk. Diets high in saturated fat have been correlated with an increased incidence of atherosclerosis and coronary heart disease.

10 FAT Among the unsaturated fatty acids, the most beneficial effect have polyunsaturated omega-3 fatty acids, which reduce risk of arrhythmias, decrease triglyceride levels, slow growth rate of atherosclerotic plaque and lower blood pressure. The low ratio of n-6:n-3 fatty acids is favourable the higher it is, the bigger the risk of inflammations, atherothrombosis and autoimmunological diseases. The most important polyunsaturated fatty acids are α- linolenic acid LNA (n-3), linoleic acid LA (n-6) and conjugated linoleic acid CLA.

11 CLA [CONJUGATED LINOLEIC ACID] Isomers of linoleic acid (C18:2) with conjugated double bonds in several positions and confirmations 75-90% cis-9, trans-11 CLA (rumenic acid) Supposed beneficial health effects of rumenic acid: prevention of cancer suppression of atherosclerosis anti-inflammatory properties.

12 FAT Trans-vaccenic acid TVA (C18:1 trans-11) is the main precursor to CLA and inhibits the development of degenerative and metabolic diseases. Eicosapentaenoic acid EPA (C20:5 n-3) is thought to possess beneficial potential in mental conditions, such as schizophrenia and ADHD, heart diseases, atherosclerosis and inflammations. Docosahexaenoic acid DHA (C22:6 n-3) can help prevent the development of Alzheimer's disease and reduce symptoms of Parkinson s disease and ADHD, has anti-inflammatory properties and reduces cardiovascular disease.

13 MAIN FACTORS INFLUENCING FATTY ACIDS PROFILE IN MILK Increased proportion of the fresh herbage in the diet results in increased proportion of rumenic acid in milk fat. Nitrogen fertilization may have a positive influence on fatty acids levels in the fresh herbage. Plant composition of fresh herbage is significant. Seasonal changes in fatty acids profile of fresh herbage are typical. Frequent cutting (grazing) interruption of process from initiation of flowering to inflorescence emergence. Weather is significant factor (temperature, light intensity and precipitation). Irrigation is a very important management tool.

14 LIPID FRACTION OF FRESH FORAGES green leaves (chloroplast) 3-10% of dry matter glycolipids and phospholipids long chain fatty acids (C14-24) 95% of total fatty acids consists of: α-linolenic acid (70-75%) linoleic acid (10-15%) palmitic acid (10%)

15 VITAMINS vitamin C antioxidant properties, beneficial effect on stability of milk fat vitamin E [α-tocopherol] anticancerogenic effect, immunostimulation, reducing cardiovascular disease, antioxidant properties vitamin A [retinol] promotion of growth, immune system, reproduction and vision β-carotene [vitamin A precursor] antioxidant and anticancerogenic properties

16 DIETARY MINERALS Calcium support of bones and teeth structure, reducing risk of osteoporosis, important role in muscle contraction, heart and digestive system health, support of synthesis and function of blood cells Magnesium beneficial potential in atherosclerosis and kidney disorders, antioxidant properties Selenium, iodine & zinc

17 ORGANIC MILK ON THE EU MARKET Organic milk production accounts for ca. 2% of total milk production in EU. The most important European producers of organic milk are Germany, Denmark and Austria their production accounts for 50% of total organic milk in Europe. The importance of organic dairy industry on the market systematically grows, both in Europe and the United States.

18 ORGANIC FARMING IN EU LEGISLATION Council Regulation (EC) No 834/2007 of 28 June 2007 on organic production and labelling of organic products and repealing Regulation (EEC) No 2092/91 Commission Regulation (EC) No 889/2008 of 5 September 2008 laying down detailed rules for the implementation of Council Regulation (EC) No 834/2007 on organic production and labelling of organic products with regard to organic production, labelling and control

19 ORGANIC FARMING BASIC STANDARDS REGARDING DAIRY COWS HUSBANDRY Commission Regulation (EC) No 889/2008 of 5 September 2008

20 ORGANIC FARMING BASIC STANDARDS REGARDING DAIRY COWS HUSBANDRY Indoors area (net area available to animals) Outdoors area (exercise area, excluding pasturage) Dairy cows 6 m 2 /head 4,5 m 2 /head Commission Regulation (EC) No 889/2008 of 5 September 2008

21 COMPARISON OF QUALITY TRAITS OF ORGANICALLY AND CONVENTIONALLY PRODUCED MILK

22 DIFFERENCES IN BASIC COMPOSITION dry matter Guinot-Thomas et al., 1991 no difference = Zadoks, 1989 higher in organic milk Lund, 1991 higher in organic milk total fat content Bergamo et al., 2003 no difference = Guinot-Thomas et al., 1991 no difference = Zadoks, 1989 Lund, 1991 Słoniewski et al., 2005 Luukkonen et al., 2005 Roesch et al., 2005 Jahreis et al., 1996 higher in organic milk higher in organic milk lower in organic milk lower in organic milk lower in organic milk lower in organic milk

23 DIFFERENCES IN BASIC COMPOSITION protein Zadoks, 1989 no difference = Lund, 1991 Guinot-Thomas et al., 1991 Słoniewski et al., 2005 Luukkonen et al., 2005 Roesch et al., 2005 higher in organic milk lower in organic milk lower in organic milk lower in organic milk lower in organic milk

24 DIFFERENCES IN LACTOSE AND UREA CONTENT lactose Toledo et al., 2002 no difference = Roesch et al., 2005 no difference = Luukkonen et al., 2005 Toledo et al., 2002 higher in organic milk urea lower in organic milk Luukkonen et al., 2005 no difference or lower in organic milk =

25 DIFFERENCES IN FATTY ACIDS COMPOSITION Research showed significantly higher levels of polyunsaturated fatty acids (including n-3) in organically produced milk. The difference between organic and conventional milk with respect to PUFA content accounts for 60%. The n-6:n-3 ratio was lower (and beneficial from a nutritional point of view) in organic milk. n-6:n-3 Organic milk < 1,25 Conventional milk > 2,50 Ellis et al., 2006; Butler & Leifert, 2009

26 DIFFERENCES IN FATTY ACIDS COMPOSITION Several studies proved higher levels of CLA and α-linolenic acid in organically produced milk. Conventional milk contained more linoleic acid the CLA/LA ratio was approximately twofold higher in organic milk, so it can be a specific indicator of organic versus conventional milk fat. Main factor for beneficial fatty acids composition in organic milk are outdoor grazing and low levels of concentrates this composition changes when switching from outdoor grazing to indoor diets in winter and the difference is less evident. Bergamo et al., 2003; Butler & Leifert, 2009

27 DIFFERENCES IN FATTY ACIDS COMPOSITION Three milk production systems have been compared: Conventional farming, indoor feeding with silages throughout the year (C 1 ) Conventional farming, grazing during summer season (C 2 ) Organic farming, grazing during summer season (O) C 1 C 2 O SFA 69,6 ± 0,5 66,8 ± 0,9 67,7 ± 1,1 MUFA 24,6 ± 0,5 25,7 ± 0,8 23,6 ± 0,4 PUFA 2,5 ± 0,2 2,7 ± 0,2 2,9 ± 0,3 trans FA 3,3 ± 0,2 4,7 ± 0,5 5,8 ± 0,7 Jahreis et al., 1996

28 DIFFERENCES IN FATTY ACIDS COMPOSITION % FA Conventional milk Organic milk SFA 67,25 ± 3,54 68,13 ± 3,51 MUFA 27,63 ± 2,94 26,19 ± 3,01 PUFA 3,33 ± 0,66 3,89 ± 0,61 total n-3 0,66 ± 0,22 1,11 ± 0,25 total n-6 1,68 ± 0,46 1,68 ± 0,44 TVA 1,75 ± 1,09 2,06 ± 0,96 CLA 0,58 ± 0,34 0,65 ± 0,28 Ellis et al., 2006

29 EFFECT OF PASTURE SEASON ON MILK YIELD, MILK COMPOSITION AND POOLS OF FATTY ACIDS IN MILK FAT (Słoniewski et al., 2005) Item milk [kg/day] Season (pasture versus indoor) Month (within season) Pasture season Indoor season * *** fat [%] *** *** protein [%] * *** SFA [g/100 g fat] MUFA [g/100 g fat] PUFA [g/100 g fat] - *** *** * FA: C4-C10 - *** FA: C11-C15 ** *** FA: C16-C20 - *** , *, **, *** effect not significant or significant at p<0.05, p<0.01, p<0.001 respectively

30 EFFECT OF PASTURE SEASON ON MILK YIELD, MILK COMPOSITION AND POOLS OF FATTY ACIDS IN MILK FAT (Słoniewski et al., 2005) Fatty acid Season (pasture versus indoor) Month (within season) Pasture season g/100g fat Indoor season C4 - *** C6 *** C8 - *** C10 *** *** C10:1 ** *** C12 *** *** C12:1 ** *** C14 ** C14:1 *** *** C15 *** * C16 *** ** C16:1 *** *** C17 * *** C18 ** ** C18:1c9 *** ** C18:1t9 - *** C18:2c9,12 *** C18 : 2(C)= CLA *** *** C18:3c9,12,15 *** C20:3c5,8,11 - *** C20:3c8,11,14 *** C20:4c5,8,11,14 *** **

31 DIFFERENCES IN ANTIOXIDANT LEVELS According to the studies results, organic milk contains significantly higher β-carotene and α-tocopherol concentrations. Conventional milk contained a higher retinol (animal form of vitamin A) level than organic milk. Higher concentrations of vitamin D in organic milk is probably caused by sun exposure of animals, that enhances synthesis of this component. The main reason for noted differences is high concentration of vitamins and provitamins in fresh fodder and silage, used in organic farms during summer season. Bergamo et al., 2003; Butler & Leifert, 2009

32 DIFFERENCES IN DIETARY MINERALS CONENT Organic milk can indicate a deficiency of dietary minerals. The use of livestock feed additives and mineral supplements in certified organic system is prohibited. It is the reason, that some dietary minerals content (i.a. Cu, Zn, Se, I, Mo) can be higher in conventionally produced milk. There are studies though, showing higher levels of calcium and sodium in organically produced milk (Zadoks, 1989; Lund, 1991).

33 REASONS FOR DEFICIENCY OF DIETARY MINERALS IN ORGANIC MILK prohibition on the use of synthetic fertilisers low concentrations of minerals in soil low content of essential elements in pasture plants deficiency of dietary minerals in milk from grazing cows Kuusela & Okker, 2007

34 BACTERIOLOGICAL QUALITY OF ORGANIC MILK One of the measures of the milk quality and, at the same time, good indicator of udder health, is somatic cell count in milk (SCC) high level of SCC indicates mastitis and decreases the quality of milk. Statistics on milk SCC on organic farms show similar or higher value of this measure, comparing to conventionally produced milk (Roesch et al., 2005; Luukkonen et al., 2005). A Danish study found no differences in milk SCC between newly transitioned organic herds and conventional herds however, the longer the herds were managed organically, the lower the milk SCC (Bennedsgaard et al., 2002).

35 BACTERIOLOGICAL QUALITY OF ORGANIC MILK Norwegian research found no difference in milk SCC but lower incidence in mastitis in organic versus conventional dairies (Hardeng & Edge, 2001).

36 BACTERIOLOGICAL QUALITY OF ORGANIC MILK Type of the farm The percentage part of the particular types of bacteria in the milk samples Streptococcus agalactiae Streptococcus faecalis Staphylococcus aureus Escherichia coli organic 7,1 74,1 1,1 2,2 conventional 12,4 78,1 3,1 1,1 Type of the farm The percentage part of the particular types of bacteria in the milk samples Pseudomonas aeruginosa Proteus vulgaris Neisseria sp. Corynebacterium sp. organic 4,1-8,1 3,5 conventional 4,0 1,1 0,5 - The most pathogenic groups of bacteria: Streptococcus agalactiae (causing the lack of milk in cows) and Staphylococcus aureus (causing coagulation of milk) were more frequent in the conventional dairy herds. Karwowska, 1999

37 BACTERIOLOGICAL QUALITY OF ORGANIC MILK Heat-resistant bacteria [in 1 ml] Butyric acid bacteria [in 100 ml] Conventional milk Organic milk Aerobic bacteria [in 1 ml] Coliform bacteria [in 1 ml] Mastitis bacteria (Mastitis streptococci) [in 1 ml] Zadoks, 1989

38 COMPOSITION OF FARM-GATE MILK IN PILOT STUDY IN UK Organic farms (n=7) Conventional farms (n=5) SCC [ 000s/ml] 293 ± ± 17 Total bacteria count [ 000s/ml] 29 ± ± 45 Fat content [%] 4,32 ± 0,60 3,98 ± 0,12 Protein content [%] 3,32 ± 0,15 3,28 ± 0,08 Herd size [no. cows] 90 ± ± 79 Av. yield/cow/lactation 5526 ± ± 741 Ellis et al., 2005

39 POLLUTANT CONTENT IN ORGANIC AND CONVENTIONAL FARM-GATE MILK IN PILOT STUDY IN UK milk farm-gate processed organic conventional organic conventional ortho PCBs [µg/kg fat] 8,22 ± 10,29 5,06 ± 7,01 4,04 21,45 non-ortho PCBs [ng/kg fat] 6,45 ± 3,62 8,06 ± 6,00 8,69 12,13 dioxins [ng/kg fat] 2,60 ± 0,91 9,88 ± 12,57 3,77 2,32 PBDEs [µg/kg fat] TEQ [ng/kg fat] 1,09 ± 0,21 0,91 ± 0,51 1,83 1,80 0,88 ± 0,21 0,91 ± 0,52 1,44 1,05 Ellis et al., 2005

40 NITRATE POLLUTION LEVELS IN MILK FROM DIFFENENT FARMS Organic farm Conventional farm Transition farm nitrate level [mg/l] 0,56 < 0,10 < 0,10 French study (above) showed that organic milk is more and regularly contaminated with nitrates in comparison to conventional and transitional dairy farms it can be related to the nitrate level in the silage or to a bad rinsing of the milking equipment after washing with HNO 3. Brazilian study found no difference in levels of nitrates and nitrites between the milk samples, indicating generally low levels. Guinot-Thomas et al., 1991; Santos et al., 2005

41 SENSORY ASSESSMENT Conventional milk Organic milk preference test smell 6,73 6,20 The tang specific smell of organically produced milk is responsible for worse sensory assessment conventional milk was much more preferred by the consumers. Nowadays people are not used to such food properties and prefer mass produced, processed milk with neutral smell. Zadoks, 1989

42 SENSORY ASSESSMENT Pellicer (2007) obtained similar results in American preference test panelists from Missouri clearly differentiated organic milk from conventional. They assessed it worse with respect to the overall flavour, liking and mouthfeel. On the other hand, Japanese consumers give the better flavour as a reason of their demand for organically produced milk (Managi et al., 2008).

43 NORWEGIAN STUDY COMPARING THE ORGANIC AND CONVENTIONAL DAIRY HERDS ORGANIC COW HERDS CONVENTIONAL COW HERDS Number of studied herds Feeding regime Management regime 50 % concentrates and silage; hay, pasture and root crops were important At least 30 min daily exercised outdoors during winter 75% concentrates and silage Exercise outdoors - very rare practice Mean lactation age 2,97 2,35 Spring calving Larger proportion Lower proportion Milk yield [kg/cow/year] Breed composition More complex, more indigenous breeds Less complex Ketosis Significantly less frequent Significantly more frequent Milk fever Significantly less frequent Significantly more frequent Mastitis Significantly less frequent Significantly more frequent Milk somatic cells No significant difference Hardeng & Edge, 2001

44 COMPARISON OF THE HEALTH STATUS OF THE DAIRY COWS FROM THE ORGANIC AND CONVENTIONAL FARMS The clinic observations and analytical results indicate that the mastitis disease occurs in the studied herds of cows. In the winter season 34% of the conventional cows and only 7% organic cows were ill with heavy mastitis. The cows from the conventional farms had smaller possibilities to fight against the infection development. Their leucocytes had lower phagocytosis capability, small possibility to decompose the phagocyted compounds and lower reactivity to mitogens. Comparison of the clinic studies and hematological, biochemical and immune indexes showed better health status of the cows form the organic farms compared to the conventional farms. Karwowska, 1999

45 CONCLUSIONS The key factor affecting the quality of animal food products is feed the use of grazing pasturage and low levels of concentrates have a beneficial effect on bioactive components in milk; the differences in nutritional value of organic versus conventional milk is not evident during winter season, when grazing is not possible. Organically produced milk has a beneficial fatty acids composition (including high CLA content), increased levels of vitamins and antioxidants thus it can play an important role in disease prevention and health promotion.

46 CONCLUSIONS The CLA/LA ratio can be a specific indicator of organic versus conventional milk fat. Due to the prohibition on the use of mineral supplements and fertilisers in organic farms, there can be a deficiency of dietary minerals in organically produced milk Sensory assessments carried out so far give equivocal results some studies indicate worse organoleptic traits of organic milk and low acceptability by the consumers; other research indicated the flavour as a selling point of organic milk. The issue has to be still investigated.

47 THANK YOU FOR YOUR ATTENTION