Effects of milk type, production month, and brand on fatty acid composition: A case study in Korea
Introduction
Milk is widely considered and consumed as a valuable source of important nutrients such as proteins, fats, and carbohydrates, as well as providing several physiologically functional compounds including bioactive peptides, antioxidants, essential vitamins/minerals, and nutritionally desirable fatty acids, notably omega-3 fatty acids (n−3 FAs). (Haug et al., 2007, Mills et al., 2011) For example, milk is a major source of fat in the human diet, accounting for 18–24%, 30–40%, and 20–25% respectively of total fat, saturated FA (SFA), and trans FA intake (Hulshof et al., 1999, Kliem et al., 2013).
In Korea, the annual raw milk production was about 2.2 megatons in 2014, ∼30% of which was used to prepare other dairy products such as cheese or yogurt (Korea_Dairy_Committee, 2014). In particular, owing to increased health awareness and the current drive towards improved quality of life, organic milk has been gaining interest in many countries. For example, organic milk already accounts for ∼10% of the total milk market in Austria and Switzerland, and in spite of the price premium compared with conventional milk, the demand for organic milk in the US, the UK, and Germany is ever increasing (Molkentin & Giesemann, 2007). In general, consumers interested in organic products (such as organic milk) associate them with a higher nutritional value and are therefore willing to pay a premium price. However, whether the nutritional quality of organic products is actually superior is a rather controversial question whose answer may vary between foodstuffs (Bahar et al., 2008, Molkentin, 2013, Samman et al., 2008).
In general, organic farming practice aims to realize ecologically and/or socially sustainable natural systems by enhancing biodiversity, biological cycles, and soil biological activity. Although there are no worldwide standards and regulations governing organic agricultural products, governmental regulation bodies and some international organizations, such as the International Federation of Organic Agriculture Movements, have been established to harmonize organic production, labelling, and certification methods (Samman et al., 2008). The rules for organic milk farming are similar in many countries. For example, all feedstuffs used should be sourced organically and be free of antibiotics, synthetic fertilizers, and pesticides (O’Donnell, Spatny, Vicini, & Bauman, 2010). According to European standards for organic farming, animals should have sufficient access to an outdoor area and their daily feed ration should contain at least 60% roughage (Capuano et al., 2014). In addition, the use of concentrates is also limited and the feed must include a high proportion of roughage throughout the year. Cereal supplementation is allowed but only as a minor component to enhance milk production during winter when fresh dairy feedstuffs such as grass are scarce. More fresh pasture or fresh grass is therefore required for organic than for conventional milk production. Furthermore, in the winter, while organic milk production relies on a sufficient supply of (organic) hay, straw, or whole-crop (or grass) silage (Molkentin & Giesemann, 2007), the efficiency of conventional milk production is commonly enhanced in integrated dairy farming systems using concentrate, cereal, and/or (conserved) silage (Boner & Forstel, 2004). More detailed information on organic milk production standards can be found in European Union regulation No. 2092/91 (EU, 2004).
Regardless of previous conflicting reports, (Bergamo et al., 2003, Toledo et al., 2002) organic milk is generally considered to contain higher amounts of nutritionally desirable components than conventional milk. Previous studies have indeed shown that organic bovine milk is richer in nutritionally desirable FAs, tocopherols, and/or carotenoids (Butler et al., 2011, Butler et al., 2008, Slots et al., 2009). However, there are health concerns related to the high SFA (i.e., lauric acid, myristic acid and/or palmitic acid) content of both organic and conventional milk, which has been associated with an increased risk of cardiovascular disease and metabolic syndromes in consumers (Butler et al., 2011, Haug et al., 2007).
The nutritional differences reported in Europe and the US between organic and conventional milk, notably in terms of FA composition, have been associated with several factors including dairy farming management systems, the milking season, sampling periods, and milk brands (Benbrook et al., 2013, Butler et al., 2011, O’Donnell et al., 2010). To our knowledge, although the volume of the organic milk market in Korea has been increasing by more than 65% each year (Korea_Dairy_Committee, 2014), nutritional differences between organic and conventional milk produced in Korea have yet to be characterized. This study therefore compares the FA contents of organic and conventional milks sold at the retail market level. The 37 FA in milk were profiled with gas chromatography coupled with a flame-ionization detector (GC–FID), and then statistically analyzed with chemometric approaches in order to reveal the milk FA variation depending on milk type, production month, and brand. The preliminary results from this study may provide a better understanding of the nutritional quality of organic milk to consumers who are interested in organic milk intake.
Section snippets
Chemicals
Analytical or high-performance liquid chromatography grade methanol (MeOH), benzene, heptane, dimethoxypropane (DMP), and sulfuric acid (H2SO4) were purchased from J. T. Baker (Phillipsburg, NJ, USA), Fisher Scientific Korea Ltd. (Seoul, Korea), or Daejung Chemical & Materials Co. (Gyeonggi-Do, Korea). The mixture of 37 standard fatty acid methyl esters (FAME, CRM47885) and pentadecanoic acid (P6125) used as an internal standard were purchased from Sigma–Aldrich Co. (St. Louis, USA).
Milk collection and sample preparation for fatty acid measurements
Three
Comparison of milk fatty acid composition and content by GC–FID
Table 1 shows the effects of milk type, production month, and brand on the FA composition and content of the samples. In this study, we examined the variation in the FA contents of three commercial organic and conventional milk brands produced in Korea from May 2014 to July 2014. Regardless of the brand or production month, the total FA content depends on the milk type (organic versus conventional), with conventional milk containing larger amounts of FA in total (p < 0.0001). This difference is
Discussion
As is well known, the FA profile of bovine milk is influenced by several factors including the milk production season, dairy feedstuffs, feeding system intensification, geographical location, and breed (Butler et al., 2008, Butler et al., 2011, Ellis et al., 2006). Climatic conditions may also affect milk quality through their impact on forage availability and quality (Butler et al., 2011). In particular, the dietary intake of dairy cows has been shown to have a more significant effect on milk
Conclusions
In summary, this study shows that conventional milk is richer in total FAs than organic milk, and the total FA content of milk monthly varies, higher in July than in May or June (p < 0.0001). Indeed, the predominant FAs (C14:0, C16:0, and C18:0, except for C18:1 n−9) in both organic and conventional milk are typically higher in June or July than in May. Compared with conventional milk, the concentrations of PUFAs including essential FAs are ∼45% higher in organic milk, and the PUFA/MUFA and n−3/n
Acknowledgements
This paper is supported by Konkuk University in 2015. The authors thank the reviewers for their perceptive and helpful comments.
References (36)
- et al.
Seasonal variation in the C, N and S stable isotope composition of retail organic and conventional Irish beef
Food Chemistry
(2008) - et al.
Fat-soluble vitamin contents and fatty acid composition in organic and conventional Italian dairy products
Food Chemistry
(2003) - et al.
Fat composition of organic and conventional retail milk in northeast England
Journal of Dairy Science
(2011) - et al.
Verification of fresh grass feeding, pasture grazing and organic farming by cows farm milk fatty acid profile
Food Chemistry
(2014) - et al.
Determination of organic milk authenticity using carbon and nitrogen natural isotopes
Food Chemistry
(2014) - et al.
Comparison of grass and legume silages for milk production. 1. Production responses with different levels of concentrate
Journal of Dairy Science
(2003) - et al.
Increasing the concentrations of beneficial polyunsaturated fatty acids in milk produced by dairy cows in high-forage systems
Animal Feed Science and Technology
(2006) - et al.
Quick changes in milk fat composition from cows after transition from fresh grass to a silage diet
Animal Feed Science and Technology
(2004) - et al.
Comparison of the fatty acid composition of fresh and ensiled perennial ryegrass (Lolium perenne L.), affected by cultivar and regrowth interval
Animal Feed Science and Technology
(2003) - et al.
Comparing the fatty acid composition of organic and conventional milk
Journal of Dairy Science
(2006)
One-step lipid extraction and fatty acid methyl esters preparation from fresh plant tissues
Analytical Biochemistry
Effect of feed on the composition of milk fat
Journal of Dairy Science
Seasonal variation in the fatty acid composition of milk available at retail in the United Kingdom and implications for dietary intake
Food Chemistry
Milk intelligence: Mining milk for bioactive substances associated with human health
International Dairy Journal
Applicability of organic milk indicators to the authentication of processed products
Food Chemistry
Survey of the fatty acid composition of retail milk differing in label claims based on production management practices
Journal of Dairy Science
Fatty acid composition of edible oils derived from certified organic and conventional agricultural methods
Food Chemistry
The importance of the ratio of omega-6/omega-3 essential fatty acids
Biomedicine & Pharmacotherapy
Cited by (18)
Authentication of organically produced cow milk by fatty acid profile combined with chemometrics: A case study in China
2023, Journal of Food Composition and AnalysisAnalysis of oxylipins to differentiate between organic and conventional UHT milks
2021, Food ChemistryCitation Excerpt :In general terms, organic milk contains less omega-6 and more omega-3 fatty acids than conventional milk (Benbrook, Butler, Latif, Leifert, & Davis, 2013; Butler et al., 2008; Capuano, Gravink, Boerrigter-Eenling, & van Ruth, 2015; Chung, Kim, Park, Oh, & Kim, 2016; Schröder, Yousefi, & Vetter, 2011); among them, α-linolenic acid (ALA) has been described as the best fatty acid to distinguish between organic and conventional milk. Higher amounts of ALA in organic milk are caused by greater amounts of fresh forage in the diet as a result of the major periods of outdoor grazing in organic farming (Benbrook et al., 2013; Butler et al., 2008; Capuano, Van Der Veer et al., 2014; Capuano et al., 2015; Chung et al., 2016; Molkentin, 2009; Schröder et al., 2011). In this sense, various articles have described that organic milk has a fatty acid profile richer in the conjugated linoleic acid isomer C18:2 [trans-9,11] (CLA9) (Benbrook et al., 2013; Butler et al., 2008; Chung et al., 2016; Molkentin, 2009), vaccenic acid (VA) (Butler et al., 2008), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and the branched chain fatty acid phytanic acid (Benbrook et al., 2013).
Discrimination of organic milk by stable isotope ratio, vitamin E, and fatty acid profiling combined with multivariate analysis: A case study of monthly and seasonal variation in Korea for 2016–2017
2018, Food ChemistryCitation Excerpt :The limit of detection (LOD = 3 × SD/S) and limit of quantification (LOQ = 10 × SD/S) were calculated from the prepared calibration curves, where SD is the standard deviation of the y-intercept of the calibration curve, and S is the slope of each calibration curve (Chung et al., 2017). Fatty acids in milk samples had to be extracted and converted to FAME prior to GC-FID analysis (Chung et al., 2016). The 50-mg milk powder samples were transferred to Teflon™-lined cap tubes, and an internal standard, 0.2-mg pentadecanoic acid (C15:0), was added to the same tubes.
Effects of soil type and organic fertilizers on fatty acids and vitamin E in Korean ginseng (Panax ginseng Meyer)
2017, Food Research International