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.

Boar taint detection using parasitoid biosensors.

The off-flavor boar taint associated with the substances skatole, androstenone, and possibly indole represents a significant problem in the pig husbandry industry. Boar taint may occur in meat from uncastrated sexually mature male pigs; consumers commonly show a strong aversion to tainted meat. Consequently, there is a need for rapid methods to sort out and remove tainted carcasses at the slaughterline. We tested the ability of wasps, Microplitis croceipes to perceive and learn the 3 boar taint compounds both individually and in combination using classical conditioning paradigms. We also established the effectiveness and reliability of boar taint odor detection when wasps were used as biosensors in a contained system called the "wasp hound" using a cohort of trained wasps. We found that the wasps are able to successfully learn indole, skatole and to also detect them when presented a 1:1:1 mixture of all 3 compounds. This was shown for both a single hand-manipulated wasp bioassay and when using the "wasp hound" detector device. In contrast, the wasps showed a weak conditioned response to androstenone at the concentration tested. The estimated gas phase concentrations that the wasps perceived during training were in the range of 10 ± 0.4 pg/s for skatole and indole, and 2 ± 0.5 pg/s for androstenone. We conclude that use of these wasps as biosensors presents a promising method for boar taint detection and discuss future training paradigms that may improve their responses to compounds such as androstenone. Practical Application: The development of a perceptive, inexpensive, and reliable means of detecting boar taint before the product is presented to sensitive consumers.

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.

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 O(2) concentration differed between the photosensitizers. It is suggested that the rate of photobleaching is a balance between type I and type II photoreactions.

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.

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.