Marinating as a technology to shift sensory thresholds in ready-to-eat entire male pork meat

This study investigated the effect of marinades in improving the eating quality in ready-to-eat boar meat. Neck chops with fat content below 18.9%, skatole ⩽1.1 ppm (range 0.03–1.1) and androstenone ⩽5.6 ppm (range 0.01–5.6) were used. In a screening experiment different marinades were tested for their ability to mask boar taint (defined as manure and urine odour and flavour). Liquid smoke and oregano extracts appeared to have the best potential for masking, and were studied in detail. Results from the study indicated that marinated chops with skatole content of approximately 0.4 ppm appeared similar to castrates in boar taint. Chops with skatole contents above 0.7 ppm remained unmasked despite the use of strongly flavoured marinades. Unmarinated chops served at 60 °C were more tainted than those served at 15 °C, but scored lower for boar taint when reheated, although the concentrations of androstenone and skatole remained the same. The fat content of the chops was not well correlated to the perception of boar taint. The attributes manure and urine were correlated with the level of skatole, but urine attribute was not a good indicator of the androstenone level.     

Impact of cooling rates on the staling behavior of cooked rice during storage

The impact of cooling rates (0.40, 1.11, 1.42, 1.64, 2.47 and 3.36 °C/min) on starch retrogradation and textural properties of cooked rice was evaluated. The relationship between cooling rates and different properties were determined using Pearson correlation. Starch retrogradation enthalpy (ΔH_r) of cooked rice was determined by differential scanning calorimetry, and textural properties were determined by a Texture Analyser. This study showed that the ΔH_r value and hardness value had a negative correlation with cooling rate during storage, −0.963  r  −0.716, P < 0.01; −0.826  r  −0.706, P < 0.05, respectively. However, a positive correlation was found between adhesiveness and cooling rate (0.237  r  0.882, P < 0.05). These results indicated that the cooked rice chilled with slower cooling rate retrograded faster than chilled with rapid cooling rate. Therefore, high quality cooked rice can be produced by rapid cooling process.     

Performance and fat quality of heavy pigs fed maize differing in linoleic acid content

Maize shows wide differences in linoleic acid due both to total lipid content and to fatty acid profile. Therefore, diets containing the same high maize percentage (up to 55%) can differ in linoleic acid content and lead to subcutaneous fats of differing suitability for raw ham curing. Two trials were performed on heavy pigs; in the first, 60 pigs (body weight 48.7 ± 5.1 kg) were fed three diets made using three maize batches differing in linoleic acid due to different total lipid content, in the second trial, 40 pigs (live weight 70.4 ± 3.4 kg) were fed two diets made using two maize batches differing in linoleic acid due to their fatty acid profile. Pigs were slaughtered at 170 kg of live weight. In both trials, the growth and slaughtering performance did not differ. In the first trial the three diets lead to a different content of linoleic acid both in subcutaneous (low linoleic vs medium linoleic vs high linoleic P  0.01) and intramuscular fat (low linoleic vs high linoleic P  0.05). In the second trial different linoleic acid content was observed for subcutaneous fat (P  0.01) but not for intramuscular fat. To formulate diets for heavy pigs, it is crucial to know the linoleic acid content of the maize used, because differences of only 0.3% can lead to significant differences in fatty acids composition of depot fats.     

Effect of a 10-day ageing at 30°C on the texture of dry-cured hams processed at temperatures up to 18°C in relation to raw meat pH and salting time

The aim of this study was to investigate the effect of a 10-day ageing at 30 ± 2 °C on the texture of dry-cured hams processed at temperatures up to 18 ± 2 °C for 12 months in relation with raw ham pH and salting time. Three pH groups (semimembranosus muscle at 24 h post-mortem: Low pH < 5.7, Medium pH = 5.7  pH  5.9, and High pH > 5.9), three salting times (6 d, 10 d and 14 d) and two ageing temperatures (18 °C and 30 °C) were investigated. Physicochemical characteristics, instrumental and sensory texture and product sliceability were evaluated on biceps femoris and semimembranosus muscles. Hams with pH_SM24 < 5.7 should be avoided in order to reduce the incidence of texture problems in dry-cured ham elaboration. Texture problems are especially important in hams with a reduced salt content that are mechanically sliced (not frozen). A 10-day ageing at 30 °C could be useful for reducing the soft texture problems in dry-cured hams processed at temperatures up to 18 °C for 12 months without affecting the product flavour.     

Carcass fatty acid mapping

We hypothesized that subcutaneous (s.c.) adipose tissue would differ in monounsaturated (MUFA) and saturated fatty acid (SFA) composition among different depots throughout a beef carcass. To test this, 50 carcasses from a variety of breed types and backgrounds were sampled. External fat samples were collected from eight different carcass locations: round, sirloin, loin, rib, chuck, brisket, plate and flank. The brisket was significantly lower (P = 0.001) in palmitic (16:0) and stearic (18:0) acid than the other seven sampling sites. The brisket contained the highest concentration of MUFA (P = 0.001) and the lowest concentration of trans-vaccenic acid (P = 0.002) and SFA (P  0.002). There was a high, negative correlation between palmitoleic and stearic acid (R² = 0.76). The flank had the highest slip point (39 °C; a measure of melting point), whereas the brisket had the lowest slip point (25 °C) (P  0.001). We conclude that substantial differences exist in fatty acid composition across fat depots, which may be useful in formulating value-added processed beef products.     

The effects of method of castration,rearing condition and diet on sensory quality of pork assessed by a trained panel

Beside surgical castration possible alternatives helping to reduce the incidence of boar taint in cooked pork are rearing conditions, immunocastration and feeding strategies for entire males known to lower the skatole levels. The goal of this study was to assess the effects of these alternatives on the sensory acceptability of pork. In experiment 1, carcasses from barrows, entire males (EM) and entire males fed raw potato starch (EM+) 7 d before slaughter were selected based on the androstenone (≤ 2 µg/g) and skatole (≤ 0.32 µg/g) levels. In experiment 2, carcasses from barrows, immunocastrates (IC), entire males either group-penned (EMG) or individually penned (EMP) were selected based on the aforementioned criteria. Boar odour and boar flavour intensities of longissimus dorsi (LD) and neck chops were evaluated by trained panellists. Boar odour and flavour scores were higher (P < 0.01) in neck than LD chops. Although skatole tissue levels in barrows and EM+ were similar (P > 0.05), boar odour and flavour scores were greater (P < 0.05) in EM+ than barrows. In experiment 2, scores for boar odour and flavour were lower (P < 0.05) in pork from barrows and IC than EMP, with intermediate values for EMG. In conclusion, we observed a discrepancy between the known boar taint compounds androstenone and skatole and sensory acceptability, which indicates that other factors influenced the perception of boar taint. Thus, surgical castration with or without anesthesia or immunocastration are still the safest methods to avoid boar taint.     

Quantification of myosin heavy chain isoform in porcine muscle using an enzyme-linked immunosorbent assay

The aim of the present study (part of an EU AIR programme on boar taint) was to make objective the perception of boar taint in entire male pork, and to relate the perception to skatole and androstenone levels. Trained analytical sensory panels in seven European countries assessed pig meat with known levels of androstenone and skatole. The panels performed a sensory profiling using the attributes pig, urine, manure/stable, naphthalene/mothballs, rancid, sweet, sweat and abnormal, both for odour and flavour in separate sessions. It turned out to be difficult to harmonise sensory methodology for seven sensory panels throughout the EU, especially with respect to the exact level of training the panellists received. Sensory panels in general were able to differentiate between the two compounds and between different levels of the compounds, though substantial differences between the panels in the different countries existed. Androstenone was found to relate mostly to the urine attribute, while skatole related mostly to manure and, to a lesser extent, to naphthalene.     

Effect of feeding fermentable fibre-rich feedstuffs on meat quality with emphasis on chemical and sensory boar taint in entire male and female pigs

Skatole, androstenone and other compounds such as indole cause boar taint in entire male pork. However, female pigs also produce skatole and indole. The purpose of this experiment was to minimise boar taint and increase overall impression of sensory quality by feeding entire male and female pigs with fibre-rich feedstuffs. The pigs have been fed three organic diets for either 1 or 2 weeks prior to slaughter of which two diets contained different fermentable fibre-rich feedstuffs – 10–13.3% dried chicory roots or 25% blue lupines. These two treatments were compared with pigs fed with an organic control diet for either 1 or 2 weeks prior to slaughter. Lupines significantly reduced skatole in blood and backfat for both genders after 1 week. Moreover, lupines showed negative impact on growth rate and feed conversion whilst chicory showed no significant differences in this respect. However, the indole concentration was significantly lower in chicory than lupine fed pigs. From a sensory perspective, chicory and lupine feeding reduced boar taint since odour and flavour of manure related to skatole and urine associated to androstenone were minimised. The level of boar taint in the entire male pigs was most effectively reduced after 14 days by both fibre-rich feeds while lupine had the largest influence on “boar” taint reduction in female pigs.     

Predicting the likelihood of developing boar taint: Early physical indicators in entire male pigs

Three potential early-age predictors of which boars are likely to develop boar taint (testes volume, skin lesions and dirtiness) were measured on 102 boars every fortnight from 10 weeks of age until slaughter. These predictors were correlated with the level of boar taint according to the hot iron method and the concentrations of skatole and androstenone as determined by chemical analysis. The chance of no/low boar taint according to the hot iron method decreased with higher testes volume (weeks 22 and 24) and increased with skin lesion score (weeks 12, 16 and 18). For the concentrations of androstenone and skatole, the strongest correlation was found with testes volume in week 12. Skin lesions in week 16 were negatively correlated with skatole levels. Dirtiness was negatively correlated with skatole concentrations (week 18) but positively correlated with androstenone concentrations (weeks 20 and 22). Testes volume has the greatest potential for predicting the likelihood of developing boar taint.     

Effect of feeding fermentable fibre-rich feedstuffs on meat quality with emphasis on chemical and sensory boar taint in entire male and female pigs

Skatole, androstenone and other compounds such as indole cause boar taint in entire male pork. However, female pigs also produce skatole and indole. The purpose of this experiment was to minimise boar taint and increase overall impression of sensory quality by feeding entire male and female pigs with fibre-rich feedstuffs. The pigs have been fed three organic diets for either 1 or 2 weeks prior to slaughter of which two diets contained different fermentable fibre-rich feedstuffs – 10–13.3% dried chicory roots or 25% blue lupines. These two treatments were compared with pigs fed with an organic control diet for either 1 or 2 weeks prior to slaughter. Lupines significantly reduced skatole in blood and backfat for both genders after 1 week. Moreover, lupines showed negative impact on growth rate and feed conversion whilst chicory showed no significant differences in this respect. However, the indole concentration was significantly lower in chicory than lupine fed pigs. From a sensory perspective, chicory and lupine feeding reduced boar taint since odour and flavour of manure related to skatole and urine associated to androstenone were minimised. The level of boar taint in the entire male pigs was most effectively reduced after 14 days by both fibre-rich feeds while lupine had the largest influence on “boar” taint reduction in female pigs.     

Effects of cooling temperature and hot carcass weight on the quality of lamb

The effects of cooling temperature (CT) (0–2, 2–4, or 4–6 °C) and hot carcass weight (HCW) (either 10.5 or 12.0 kg) on weight loss (WL) and meat quality were evaluated in 60 lamb carcasses of Rasa Aragonesa breed. Carcasses were exposed to CT throughout 90 h. WL was assessed at 18, 42, 66, and 90 h post-slaughter. pH, colour, instrumental measurement of texture, oxidation, and sensory parameters were evaluated in longissimus thoracis et lumborum aged for 96 h following standard methods. Sensory test involved a trained test panel. No significant interactive effects among the parameters evaluated were detected in the study. The lower the CT, the higher the WL after 90 h in storage (0.25% lost each 2 °C decrease), the higher final pH, and the lower lightness, the higher hue and chroma of the meat. Toughness was higher in meat cooled at 2–4 °C than in meat cooled at temperatures above or below this range. Neither oxidation nor sensory variables were affected by CT. Regarding on HCW, light carcasses exhibited higher WL (2.39% versus 2.04% after 90 h of cooling), higher final pH, and lower levels of oxidation than did heavier carcasses. Neither colour nor instrumental measurement of texture was affected by HCW. Lamb and fat odour and metallic and acid flavour intensities were significantly greater in the heavier carcasses, although it did not affect overall acceptability. Both CT and HCW should be considered as main effects on lamb quality, especially CT.     

Sensory characterization of meat from pigs vaccinated against gonadotropin releasing factor compared to meat from surgically castrated,entire male and female pigs

Boar taint is a sensory defect mainly due to androstenone and skatole. The most common method to control boar taint is surgical castration at an early age. Vaccination against gonadotropin releasing factor (also known as immunocastration) is an alternative to surgical castration to reduce androstenone content. In this experiment, loins from 24 female (FE), 24 entire male (EM), 24 vaccinated males (IM) and 23 surgically castrated males (CM) were evaluated by eight trained panellists in 24 sessions. Loins were cooked in an oven at 180 °C for 10 min. Furthermore loins were evaluated by consumers and its androstenone and skatole content were also chemically determined. Meat from EM had higher androstenone and skatole odour and flavour than meat from FE, IM and CM and lower sweetness odour scores. High correlations were found between androstenone and skatole levels assessed by trained panelists, chemical analysis and consumers’ acceptability. Moreover meat from EM is mainly related to androstenone and skatole attributes.     

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.     

Optimisation of antioxidant activity of grape cane extracts using response surface methodology

Solid–liquid extraction and response surface methodology were used to optimise conditions for the antioxidant activity of grape cane extracts. The independent processing variables were ethanol concentration, temperature and solvent to solid ratio. Ethanol concentration and temperature significantly affected antioxidant activity measured by the Trolox equivalent antioxidant capacity (TEAC) assay and the oxygen radical absorbance capacity using fluorescein (ORAC_FL) method (p  0.01), whereas the solvent to solid ratio did not significantly affect the activity (p > 0.05). Antioxidant activity of the extracts, determined by the TEAC assay, varied from 85.6 to 238.6 μmol Trolox equivalents/g of dry sample. ORAC_FL values ranged from 308.4 to 1302.7 μmol Trolox equivalents/g of dry sample. Ethanol concentrations of 40.4% and 55.4% were optimal for the highest antioxidant activities measured by the TEAC assay and the ORAC_FL method, respectively. The optimal temperature was 83.6 °C. Antioxidant activity correlates with total phenolic content of extracts.     

Predicting the likelihood of developing boar taint: Early physical indicators in entire male pigs

Three potential early-age predictors of which boars are likely to develop boar taint (testes volume, skin lesions and dirtiness) were measured on 102 boars every fortnight from 10weeks of age until slaughter. These predictors were correlated with the level of boar taint according to the hot iron method and the concentrations of skatole and androstenone as determined by chemical analysis. The chance of no/low boar taint according to the hot iron method decreased with higher testes volume (weeks 22 and 24) and increased with skin lesion score (weeks 12, 16 and 18). For the concentrations of androstenone and skatole, the strongest correlation was found with testes volume in week 12. Skin lesions in week 16 were negatively correlated with skatole levels. Dirtiness was negatively correlated with skatole concentrations (week 18) but positively correlated with androstenone concentrations (weeks 20 and 22). Testes volume has the greatest potential for predicting the likelihood of developing boar taint.     

Quantitative determination of the boar taint compounds androstenone,skatole, indole, 3α-androstenol and 3β-androstenol in wild boars (Sus scrofa) reveals extremely low levels of the tryptophan-related degradation products

The major boar taint compounds androstenone and skatole as well as the minor compounds indole, 3α-androstenol and 3β-androstenol were determined in back fat samples of 23 male wild boars by applying a recently published SIDA–HS-SPME–GC/MS method. The boar pheromones androstenone, 3α-androstenol and 3β-androstenol were found in extraordinary high concentrations, resulting in mean values of 3329 ng/g androstenone, 1273 ng/g 3α-androstenol and 545 ng/g 3β-androstenol. Interestingly, skatole was not detectable in about 50% of the boars and negligibly low in all other samples as expressed by a mean skatole value of only 14 ng/g. Indole was also found in every sample, but again in low concentrations with a mean value of 40 ng/g. Possible factors explaining this remarkably low skatole deposition in wild boars such as intestinal flora and anatomy, dietary composition, housing or genetic predisposition are discussed in this paper.     

Supercritical Carbon Dioxide Extraction of Androstenone and Skatole from Pork Fat

Boar taint, an unpleasant odor observed in pork from some mature intact male pigs, is attributed primarily to the presence of two compounds in boar fat, androstenone (Sα-androst-16-ene-3-one) and skatole (3-methyl indole). A rapid extraction method for the preparation of fat samples for androstenone/skatole screening assays would lead to more efficient use of boar carcasses for pork production. Supercritical carbon dioxide removed 97 ± 2% of the androstenone (extraction at 40°C; 5 min) and 65 ± 3% of the skatole (extraction at 40°C; 20 min) from 0.5 g of boar backfat. Supercritical CO₂ provides the basis for a fairly rapid extraction method to remove compounds associated with boar taint.     

Physicochemical properties of whey protein isolate stabilized oil-in-water emulsions when mixed with flaxseed gum at neutral pH

Concentrations ranging from 0% to 0.33% (w/v) of gum (Emerson and McDuff) were added to the emulsions at pH 7. Particle size distribution, viscosity, ζ-potential, microstructure, and phase separation kinetics of the emulsions were observed. Both polysaccharides and protein coated droplets are negatively charged at this pH, as shown by ζ-potential measurements. At all the concentrations tested, the addition of gum did not affect significantly (p < 0.05) the apparent diameter of the emulsion droplets. At low concentrations (gum  0.075% (w/v)), no visual phase separation was observed and the emulsion showed a Newtonian behaviour. However, at concentrations above the critical concentration of gum, depletion flocculation occurred: when 0.1 flaxseed gum was present, there was visual phase separation over time and the emulsion exhibited shear-thinning behaviour. These results demonstrate that flaxseed gum is a non-interacting polysaccharide at neutral pH; it could then be employed to strengthen the nutritional value of some milk-based drinks, but at limited concentrations.     

A human nose scoring system for boar taint and its relationship with androstenone and skatole

A system for sensory evaluation of boar taint was used to evaluate boar taint in fat samples from 6574 entire males. The term "human nose scoring" has been used to describe this system. The samples from each boar were heated with a hot iron and three panelists assigned scores of 0 to 4. The reproducibility of HNS ranged from 0.19 to 0.32 reflecting natural variation in the ability of human beings to detect different odors. The correlations of HNS with androstenone ranged from 0.22 to 0.52, while those with skatole ranged from 0.31 to 0.89, suggesting that skatole is a better predictor of boar taint. Considering (1) the relationship of HNS with the boar taint compounds, (2) the ability of HNS to capture variation not accounted for by the boar taint compounds, (3) low estimation costs and (4) low time requirements, HNS can be used in large scale evaluations of boar taint.