Frank Lundby

Determination of total fat and moisture content in meat using low field NMR.

The use of low field Nuclear Magnetic Resonance (LF-NMR) is shown to be a fast and accurate alternative to the use of drying and solvent extraction, to determine the content of raw or total fat and moisture in a biological system. The proposed NMR method for fat determination in minced meat proves to be a robust method that does not require sophisticated post handling of the experimental data. The calibration procedure is very easy, as a calibration value from a sample of known weight containing 100% oil is the only calibration needed for the proposed experimental set-up. On three sets, each containing 42 samples of minced beef where the fat content varies from less than 1 to 14%, the fat content has been measured either by NMR on fresh tissue, NMR on dried tissue, or by the use of solvent extraction determining the content of raw fat [Foss-let fat analyser (AOAC Official Method 976.21]. Comparison of the three methods for determination of the fat content shows satisfactory agreement between the different methods. On six samples of minced pork meat, the fat and moisture content have been determined. The total fat content was determined by NMR both on fresh and dried tissue. The moisture content was determined by NMR of fresh tissue and by drying of the tissue. The different methods for determining fat and moisture content agreed for the minced pork samples.

Noncontact salt and fat distributional analysis in salted and smoked salmon fillets using X-ray computed tomography and NIR interactance imaging.

To be able to monitor the salting process of cold smoked salmon, a nondestructive imaging technique for salt analysis is required. This experiment showed that X-ray computed tomography (CT) can be used for nondestructive distributional analysis of NaCl in salmon fillets during salting, salt equilibration, and smoking. The combination of three X-ray voltages (80, 110, and 130 kV) gave the best CT calibrations for NaCl, with a prediction error (root mean square error of cross-validation, RMSECV) of 0.40% NaCl and a correlation (R) of 0.92 between predicted values and reference values. Adding fat predictions based on NIR interactance imaging further improved the NaCl prediction performance, giving RMSECV = 0.34% NaCl and R = 0.95. It was also found that NIR interactance imaging alone was able to predict NaCl contents locally in salted salmon fillets with RMSECV = 0.56% and R = 0.86.

Fat distribution analysis in salmon fillets using non-contact near infrared interactance imaging: a sampling and calibration strategy

An online NIR interactance imaging instrument was tested for fat distribution analysis in raw and salted salmon fillets. Approximately 3000 spectra were collected for each fillet when passing under the instrument on a conveyor belt (approximately 1s exposure). The instrument was calibrated using five cylindrical plugs (15 mm diameter) from each fillet. The fat content was measured for each of these plugs using 1H-NMR spectrometry and the spectra from each plug region were averaged and used for calibration and validation. It was found that online NIR interactance imaging is well-suited for distributional fat analysis in raw and salted intact salmon fillets. The local sampling and calibration strategy using 15 mm diameter plugs for reference analysis and spectral averaging was found to provide relevant information and robust models. The average prediction errors (root mean square error of cross-validation) for raw and salted fillets in combination were approximately 2% fat for local plug regions.

Autofluorescence quantifies collagen in sausage batters with a large variation in myoglobin content.

In order to clarify the potential of the method of autofluorescence for determining the collagen content in meat batter, an experimental design was used where the emission originating from collagen was unrelated to the effect of myoglobin absorbance on the emission spectra. Muscles like beef Masseter, beef Latissimus dorsi and pork Glutens medius assured a large variation in myoglobin content, and made absorbance from myoglobin account for 65-84% of the variation in the emission spectra at wavelengths normally thought interesting for collagen quantification. Collagen (range 1.3-4.0%) accounted for 7-18% of the variation in the autofluorescence emission spectra. Collagen content could be predicted from the emission spectra provided multivariate regression techniques were used. Pre-processing of spectra reduced the prediction error for collagen by 0.03-0.12%, depending on method used; the lowest prediction error obtained being 0.48%. The method of autofluorescence gave lower prediction errors for collagen content than did the method of near infrared reflectance when applied to the same batters.

Natural faecal fluorophores and the potential of chlorophyll based markers to optimise fluorescence as a real-time solution for the detection of faecal contamination on carcasses

More accurate and sensitive visualisation of faecal contamination in the abattoir would significantly reduce the risk posed by harbouring pathogenic micro-organisms. We carried out a preliminary investigation of the range of fluorophores found naturally in faeces from typical ruminant diets. Sixteen ewes were offered either: i) fresh forage (FF), ii) grass silage (GS), iii) grass hay (GH) or iv) concentrate and barley straw (CB). Animals offered FF diets had a greater concentration (P<0.001) of chlorophyll based compounds in their faeces and subsequent fluorescent emission spectra. In a second experiment we investigated a range of fluorescent markers against a basal concentrate and barley straw diet. Ten Cheviot sheep were split into five treatment groups during a duplicate 5 × 5 Latin square design. Four of the groups received a chlorophyll based marker at a rate of 2g/d: i) Mg-Chlorophyllin (MgC), ii) Fe-Chlorophyllin (FeC), iii) Zn-Chlorophyllin (ZnC) or iv) Spirulina (Chlorophyll a extract from blue green algae, Sp). The last group received no supplement as the control (Con). The appearance of chlorophyllin markers and their derivatives in faeces was similar with mean concentrations of 3.1 and 7.2 μg/g DM, respectively. The most intense fluorescent signal was shown with MgC followed by ZnC, FeC, Sp and Con at 685 nm. The use of markers in pre-slaughter diets would improve the accuracy of faecal detection as a result of greater fluorescence and specific emission wavelengths which do not overlap with natural meat components to help with visualisation.

Effect of Oxygen Concentration on Photo‐oxidation and Photosensitizer Bleaching in Butter

The effect of headspace oxygen concentration and color of light on photo‐oxidation and degradation of photosensitizers in butter was studied. Butter samples were stored under 0%, 0.4%, 0.8%, 1.6%, 3.0%, 5.0%, 21% oxygen, and exposed to violet, green or red light. Storage time was 36 h. Degree of photo‐oxidation was measured by a trained sensory panel. Photobleaching of six different photosensitizers was estimated based on front face fluorescence excitation and emission landscapes and spectral curve resolution (parallel factor analysis). The higher oxygen concentration, the more sensory degraded were the samples. Violet light resulted in slightly higher degrees of photo‐oxidation than green and red light for low oxygen concentrations. Bleaching rate and course as function of O2 concentration differed between the photosensitizers. It is suggested that the rate of photobleaching is a balance between type I and type II photoreactions.

Potential of Chlorophyll-Rich Feed Ingredients To Improve Detection of Fecal Contamination in the Abattoir

The use of fecal fluorescence to improve detection of contamination of carcasses in the abattoir was previously reported. However, incidents of false negatives can result when animals are offered diets that contain little chlorophyll (e.g., concentrate). Here, we investigated the potential of incorporating a high-chlorophyll-containing feed ingredient (concentrated alfalfa extract; CAE) into the diets of sheep and cattle to improve fecal fluorescence intensity. The sheep experiment evaluated the fecal fluorescence of animals from pasture, when fed a concentrate-barley straw diet and when the concentrate diet incorporated CAE (100 g of dry matter a day). Fecal chlorophyll and metabolite content was highest on the pasture-fed animals and increased significantly over the concentrate diet when CAE was included. Subsequently fluorescent intensity was increased from 15,000 to 36,000 arbitrary units for concentrate and CAE-concentrate diets, respectively, compared with 59,000 for the pasture-fed animals. The cattle experiment investigated the potential of CAE to improve fluorescence of feces from a concentrate diet as well as a silage diet at two levels of incorporation (75 and 150 g CAE/kg of dry matter intake). This study also determined the fluorescence of digesta and carcass contamination in the abattoir on a subset of carcasses. In agreement with the sheep study, CAE significantly improved fluorescence of feces and digesta when added to a concentrate diet, but had little effect on improving fecal fluorescence from the silage-fed animals. This was thought to be related to greater chlorophyll degradation in the rumen or/and the dark nature of the silage feces acting as a quencher of emitted fluoresced light. Incorporating high-chlorophyll-containing plant ingredients into ruminant concentrate diets will improve detection of fecal contamination by reducing false-negative readings. However, they will have little effect on false-positive readings due to the range of wavelengths emitted by natural chlorophyll and its metabolites. Implications and potential solutions for this are discussed.