Analysis of amino acid composition of sheep colostrum by near-infrared spectroscopy

Citric acid (KC) in milk is indicator of cow energy metabolism. Milk laboratories set up KC determination. A method can be infra-red analyse (MIR-FT). The goal was to develop a relevant method for reference sample preparation for MIR-FT (indirect method, Lactoscope FTIR and MilkoScan FT 6000) calibration. As reference was used a photometric method (c; 428 nm). KC was added (n = 3) into some reference milk samples (n = 10, bulk milk). Mean value was 9.220 ± 3.094 mmol . l−1 with variation range from 6.206 to 15.975 mmol . l−1. Recovery c was from 100.8 to 120.2 %. Correlation between c and MIR-FT were from 0.979 to 0.992 (P < 0.001). These were lower in the set of native milk samples (n = 7), from 0.751 (Lactoscope FTIR; P < 0.05) to 0.947 (MilkoScan FT 6000; P < 0.001) in comparison to original values from 0.981 to 0.992 (n = 10; P < 0.001). Correlations between calibrated MIR-FT instruments were from 0.958 to 1.0 (P < 0.001). Average recovery for instruments (n = 12) was 101.6 ± 18.1 %. The mean differences between c method and MIR-FT after calibration (n = 4) moved from −0.001 across zero to 0.037 %. Standard deviation of differences was from 0.0074 to 0.0187 % at MilkoScan FT 6000 and from 0.0105 to 0.0117 % for Lactoscope FTIR. Relative variability of differences (MIR-F (filter technology) and FT) for major components fat (T), proteins (B) and lactose (L) in total and minor components KC and free fatty acids (VMK) was estimated to 1.0 and 7.2 and 34.4 %. The KC result is inferior than T, B and L superior than VMK. Autocorrelation (0.042; P > 0.05) of results demonstrated the independence of consecutive measurements. Milk preservation effect amounted 0.2323 (P < 0.001) with bronopol and 0.0339 (P > 0.05) mmol . l−1 with dichromate. It was (3.0 and 0.44 %) practically negligible, redeemable via relevant calibration. The results of proficiency testing in post-calibration period and evaluation of double transport stress effect samples (difference was −0.006 ± 0.071 mmol . l−1 (P > 0.05)) demonstrated the useability for central calibration system. Milk KC results of MIR-FT calibration were good and can be suitable for practical screening.

unclassified

Result interpretation of experimental calibration for milk citric acid determination via infra-red spectroscopy (MIR-FT)

Hanuš¹,

Hulová²,

Genčurová³

et al. 2014

“…This procedure is usual ly performed in mid IR or as near IR variant. Over the years a number of authors (Sjaunja, 1984 a, b, c;Sjaunja et al, 1984;Sjaunja and Andersson, 1985;Hanuš et al, 1992Hanuš et al, a, 2002Tsenkova et al, 2000;Kukačková et al, 2000;Jankovská and Šustová, 2003;Kráčmar et al, 2004;Bijgaart, 2006;Broutin, 2006;Šustová et al, 2006, 2007 have investigated calibra-tion procedures for various IR methods. This was done to measure various milk components using various indirect IR methods for result reliability and stability.…”

mentioning

confidence: 99%

Validation of modified milk reference sample in terms of its suitability for infra-red analysis calibration via evaluation of physical properties

Hanuš¹,

Genčurová²,

Kopec³

et al. 2014

Routine milk analyses using the efficient indirect infra-red method are important for the milk food chain quality. The reliability of the results depends on the calibration quality. It is important to use a relevant set of reference calibration samples (RCSs). RCSs with right range of values can be prepared using various methods. This paper was aimed to balance the impacts of dilution for decrease of main components in RCSs because of minimal change of matrix interference effects. Cow milk samples (MSs) were diluted (4/1) using distilled water, NaCl solution and a solution with specific composition (SC; because of disturbance in the balance of the milk matrix (NaCl 1.145; KCl 0.849; K2HPO4 1.8463; citric acid 1.7; urea 0.3 g / l)) for reduction in main milk components. Fat (F), crude protein (CP), lactose (L), milk freezing point (MFP), osmolality (OS) and electrical conductivity (EC) were measured in all (original as well as modified) MSs. The lowest MFP and OS were in the original milk −0.5559 °C and 274.5 mOsmol/kg. The MFP was increased to −0.4369 °C and osmolality decreased to 217.83 mOsmol/kg by the addition of water. The MFP was decreased (−0.4903 °C) and returned to original milk value by the addition of NaCl solutin. MFP was −0.4788 °C due to SC addition. The decrease was less than for NaCl. The ability of other SC components (K2HPO4, KCl, citric acid and urea) to MFP decrease is less than for NaCl solution. EC was highest for NaCl set 4.69 mS / cm, EC for SC was 4.48 mS / cm (P < 0.001). The original MSs set showed EC 4.27 mS / cm. The SC was the nearest to original MSs in terms of total mineral composition. ECs for both modifications differed (P < 0.001) from original MSs. The procedure is applicable for balance of interference effects of milk matrix because of relevant calibration.

“…Also the checking of time measurement stability of the instruments during inter-calibration interval is very important activity. In the last time the row of authors was interested in calibration procedures of various methods of infraanalyse on various milk component measurements, fl uoro-opto-electronic method on comatic cell count determination in milk and stability of results and samples in time at indirect methods of milk analyses (Sjaunja, 1984 a, b, c;Sjaunja et al, 1984;Sjaunja and Andersson, 1985;Hanuš et al, c, 1993Hanuš et al, a, b, c, 1995Hanuš et al, , 1997Hanuš et al, , 2001Hanuš et al, , 2002Hanuš et al, , 2003Hanuš et al, , 2008Tsenkova et al, 2000;Kukačková et al, 2000;Jankovská and Šustová, 2003;Kráčmar et al, 2004;Šustová et al, 2006, 2007Hering et al, 2008). According to ČSN 590536 the instruments have to be calibrated quarterly.…”

mentioning

confidence: 99%

Validation of deep freezing of pilot samples for checking of time stability of indirect analyses of basic milk composition and for their long shelf-life

Hanuš

Hering

Genčurová

et al. 2014

Essential part of raw milk component measurement is indirect infraanalyse. The checking of time measurement stability is important there. The preparation of pilot samples was described. Information about deep frozen milk pilot sample stability are sporadic. Aim of this work was to verify the stability of long-term stored and deep frozen pilot samples (FPSs). Pilot samples were frozen in liquid nitrogen bath −196 °C and after that stored at −21 °C for one month (A) and more months (B) till analyse. The pilot samples were measured by CombiFoss 6000: fat F (%); protein CP (%); lactose L (%); casein C (%); solid non fat SNF (%); urea U (mg/100ml); somatic cell count SCC (ths./ml). In the short-term (A) experiment the impact of freezing on pilot milk samples was relatively small, in the framework of acceptable value of repeatability (±0.02 %) for components. The stability of values of FPSs was better according to standard deviations for important F evaluation in H (Holstein) breed samples. The repeatability of values of FPSs in the time was very good for other components. The repeatability was better for SCC in J (Jersey) breed samples (±16.5 thousands/ml). That is why the higher variability (±30.1 thousands/ml) in H sample is visible less sceptically. The apparent result trends were not observable in the repeatability development of important milk indicators in FPSs. The mild trend was only in CP, but this trend covered absolutely very small shift (variation range). There are only oscillations, which are similar between J and H samples. It is possible to attribute these oscillations rather to instrument effects than to sample effects. The oscilations were markedly higher in the long-term (B) experiment. Between J and H samples the oscilations were very similar in curves F and L. It is also possible to attribute them more to instrumental effects. The repeatability values (standard deviations sd) of FPSs were mostly lower than ±0.06 %. It is acceptable for result agreement between indirect and reference method. Relevant sd varied from ±0.025 % for L to ±0.059 % for F (in J breed) with exception CP ±0.085 % in J sample. Also B procedure was shown as applicable for instrumental sability control in half year period. In practice the one reference value for concrete FPS is valid from one to next calibration. Persistent trend in repeatability of FPSs can indicate an inadequate instrumental drift. The applied FPS procedure is usable for stability control of instrumental measurement in milk laboratories.