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.     

Prevalence and relationships of sensory taint, 5α-androstenone and skatole in fat and lean tissue from the loin (Longissimus dorsi) of barrows, gilts, sows, and boars from selected abattoirs in the United States

This study assessed prevalence of boar taint in backfat and lean of barrows, gilts, sows, and boars, collected from abattoirs, without knowledge of the farms of origin, in different regions in the United States. Concentrations of 5α-androstenone (liquid chromatography/mass spectroscopy) and skatole (liquid chromatography with fluorescent detection) in backfat were measured. A trained panel evaluated boar taint aroma in heated samples. Mean 5α-androstenone and skatole levels were low among barrows, gilts, and sows, whereas 55.8% of boars scored above a 1.0 μg/g threshold for 5α-androstenone concentrations and 34.2% were above a 0.2 μg/g threshold for skatole concentrations. Mean aroma scores for backfat and lean from barrows, gilts, and sows were low. In comparison, 59.2% of boars had elevated mean aroma scores from fat samples and 31.7% from lean. Importantly, boar taint aroma was detectable by the trained panel in at least some animals in each of the sex classes.     

Testosterone and the incidence of boar taint: Effects of testosterone or testosterone propionate on the incidence of boar taint in implanted barrows

Boars, barrows and barrows implanted with testosterone or testosterone propionate via polydimethylsiloxane (Silastic) capsules were placed on test in individual pens at 10 weeks of age. Each animal was slaughtered at 110 kg and evaluated for growth rate, efficiency of feed utilization, carcass merit and the incidence of objectionable odors (boar taint). Five capsules of testosterone or testosterone propionate were used in barrows since they substantially elevated concentrations of serum testosterone, decreased serum LH and stimulated weights of the accessory sex glands. Large variations within and between litters of pigs were found for performance and carcass traits; thus, the influences of castration and testosterone replacement therapy on these traits were inconclusive. In contrast, the effects of castration and hormone treatment on the incidence of boar taint were more definitive. The incidence of boar taint was relatively high in boars, according to a consumer taste panel. This characteristic odor was appreciably lower in barrows and was not reinstated with either testosterone or testosterone propionate implants. These results suggest that testosterone is not itself responsible for boar taint and that 5-androstenone, the pheromone most closely associated with boar taint, is not produced by peripheral metabolism of testosterone. Additional studies are warranted to provide insight into the regulation of testicular steroid secretion in the boar and the contribution of these steroids to boar taint and protein anabolism.     

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.     

Influence of soiling on boar taint in boars

It has been suggested that skatole, one of the main compounds responsible for boar taint, can be lowered by keeping pigs clean, as skatole can be absorbed through skin and/or lungs (Hansen, Larsen, Jensen, HansenMoller & Bartongade, 1994). With this experiment, we further investigated this hypothesis by comparing extremely clean with extremely dirty animals with regard to the occurrence of boar taint. One group of boars was washed daily and pens were mucked on and littered down daily (CLEAN), a second group of boars was rubbed with faeces daily (DIRTY) and a third group of boars was kept in control conditions (CONTROL). The treatment was performed during the last four weeks before slaughter. According to the standardised consumer panel evaluations, boars subjected to extra soiling had a higher concentration of boar taint than boars that were kept extra clean. In contrast, expert panels judged general meat flavour to be inferior in CLEAN than CONTROL pigs. The home consumer panel, the hot iron method, and laboratory analyses, i.e., the presence of indole, skatole and androstenone in fat and serum, all showed no significant differences. So no clear indications towards skatole reduction by improving cleanliness of pigs were found.     

Effect of surgical castration,immunocastration and chicory-diet on the meat quality and palatability of boars

This study evaluates 1) carcass quality, meat quality and palatability for barrows, immunocastrates and boars and 2) the effect of chicory supplemented feed during 10 days before slaughter on boar meat quality.     

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.     

Effects of live weight and processing on the sensory traits,androstenedione concentration and 5-alpha-androst-16-en-3-one (androstenone) concentration in boar meat

Twenty-nine crossbred boars were used to evaluate the effects of live weight and processing on the sensory attributes and concentrations of androstenedione and androstenone (boar taint) in boar meat. Boars were stratified by litter across six weight group endpoints (90.9, 95.5, 100.0, 104.5, 109.1, and 113.6 kg). Back fat and longissimus muscle from the lumbar region were used for androstenone determination, proximate analysis and sensory evaluation. Hams were cured for sensory analysis and were used to determine androstenone concentrations. Androstenone as an off-flavor did not differ (P > 0.05) among treatments for longissimus lean or cured hams and was found to be in the “threshold” to “none detected” range. Back fat androstenone concentration was positively correlated (P < 0.05) to hot carcass weight, however, lean androstenone concentration was not (P > 0.05). No relationship was found (P > 0.05) between androstenone concentration and days on feed, average daily gain or androstenedione concentration. Additionally, further processing decreased androstenone concentration by approximately 29%.     

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.     

Preparation of dried chips from Jerusalem artichoke (Helianthus tuberosus) tubers and analysis of their functional properties

Jerusalem artichoke (Helianthus tuberosus L.) has recently attracted interest as a cheap form of biomass. As a food, tubers of the plant have a characteristic flavour and functional ingredients. For convenience of consumption and to prevent degradation of the high molecular weight moiety of inulin, we examined methods of preparing dried tuber chips. Chips contained inulin, other dietary fibres, and a small amount of polyphenol. The high activity of polyphenol oxidase in raw tubers suggested that blanching for more than 2 min would be required to maintain the paleness of the tubers while drying. Dried tubers had considerable water-holding capacity at low temperatures and viscosity-lowering activity on potato starch paste while heating. These results suggest that Jerusalem artichoke tubers could be more widely utilised in the food industry as a functional modifier of other materials.     

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.     

The effect of extrusion cooking using different water feed rates on the quality of ready-to-eat snacks made from food by-products

The effect of different levels of feed moisture (12–17%) during extrusion cooking, using a co-rotating twin-screw extruder on selected nutritional and physical properties of extruded products was investigated. Four different formulations were used based on wheat flour and corn starch with the addition of 10% brewer’s spent grain (BSG) and red cabbage (RC) trimming reducing the flour and starch. The samples were: wheat flour + BSG (WBSG), corn starch + BSG (CBSG), wheat flour + red cabbage (WRC) and corn starch + red cabbage (CRC). Process conditions utilised were: constant feed rate of 25 kg/h, screw speed 200 rpm and barrel temperature of 80 and 120 °C. The results indicated that increasing the water feed to 15% increased the level of total dietary fibre (TDF) in all the extrudates while extrusion processing increased the level of TDF in WBSG, CBSG and CRC but decreased in WRC products. Extrusion cooking increased the level of total antioxidant capacity (TAC) and total phenolic compounds (TPC) in WRC and CRC. In addition to water feed level affecting the TDF of the extrudates, also affected were the expansion ratio, bulk density, hardness, WSI, SME and colour. The protein level of the products and hardness of extrudates were related to the different formulations.     

Correlation of physicochemical and nutritional properties of dry matter and starch in potatoes grown in different locations

The physicochemical and nutritional properties of dry matter and starches were studied from 13 potato varieties grown in different locations in Canada. Pearson correlation and principal component analysis were employed to examine relationships amongst variables. Phosphorus content in starch was negatively correlated to rapidly and slowly digestible starch content, while positively correlated to resistant starch content (RS) in raw dry matter and raw starch (p < 0.001). RS content of cooked starch was positively correlated to phosphorus content (0.48, p < 0.01), enthalpy of retrograded starch (0.48, p < 0.01), peak viscosity (0.52, p < 0.001) and breakdown of starch (0.43, p < 0.01). The principal component analysis grouped the 13 potato varieties by growing location, where phosphorus content in starch was the major difference. The results would imply that phosphorus content of starch was a key factor affecting physicochemical and nutritional properties of dry matter and starch in potatoes.     

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.     

Blanching of potato with superheated steam and hot water spray

A heating system using superheated steam (SHS) and a spray of hot water microdroplets (WMD) has been developed to prevent drying of food material during SHS heating. Blanching of potato was examined with the new system (SHS + WMD), SHS, and hot water. In SHS + WMD heating, a mixture of SHS at 115 °C, 2.46 kg/h flow rate and hot water at 0.54 kg/h was used. In SHS heating, the flow rate and temperature of the SHS were 3.0 kg/h and 115 °C. The temperature of the hot water was approximately 100 °C. Potato tissue processed with hot water became soft and brittle, and its brightness and chromatic quality decreased due to absorption of water and dissolution of solid content to the water. In contrast, these quality changes were prevented in SHS + WMD and SHS heating. Heat transfer by SHS was enhanced by the presence of WMD, presumably because the water layer formed on the potato by condensation of SHS was stirred and its thermal resistance was decreased by collisions of WMD with the potato. The mass of potato processed with SHS + WMD was almost constant during the heating, while the relative mass of potato processed with SHS decreased to 96.7% with 16 min of heating.     

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.     

Influence of Castration and Diethylstilbestrol Implantation of Boars on Carcass Characteristics, Sensory Panel Evaluation, and 5 α-Androst-16-en-3-one Levels

Castration or implantation of boars with DES resulted in carcasses from heavy weight male pigs that were not significantly different in ham weight, shoulder weight, loin weight, M. longissimus area, marbling, color, firmness, tenderness, and juiciness. The carcasses differed significantly in percent lean cuts, panel odor and flavor measurements, hot iron measurements, and 5α-androstenone concentration; treatment means were arranged in order of intact boar, DES implanted boar, and barrow. Flavor and odor scores were significantly correlated with concentration of 5α-androstenone.     

The effects of dietary oregano oil supplementation on pig meat characteristics

The effects of different concentrations of dietary oregano essential oil supplementation on finishing pig meat characteristics were investigated in the present study. Thirty-two barrows and thirty-two gilts were divided into four equal groups. During the experimental period, which started when the animals were 5 months old and finished after 35 days, the first group was fed the control diet (group C), whereas the other three groups consumed the same diet, with the only difference that the feed was supplemented with oregano essential oil at concentrations of 0.25, 0.5 and 1 ml/kg of fed diet (groups OR1, OR2 and OR3, respectively). At the end of the experiment, pigs were fasted for 12 h, weighed and slaughtered. After overnight chilling, a 50 cm loin section was removed from the half of the carcasses (8 pigs per nutritional treatment; 4 barrows and 4 gilts) and transported to laboratory for further examination.     

Impfung oder Kastration zur Vermeidung von Ebergeruch – Ergebnisse einer repr?sentativen Verbraucherumfrage in Deutschland

Surgical castration of male piglets is performed routinely in most European countries to prevent the risk of boar taint in pork meat. Vaccination of male pigs against gonadotropin-releasing hormone with Improvac^? is a proven animal friendly alternative. However, consumer??s acceptance of any alternatives to current piglet castration is important, too. The aim of this study was to evaluate the awareness of boar taint, castration and vaccination against boar taint as well as consumers?? acceptance and preference of both methods. The study was performed in Germany in cooperation with the Institute for Public Opinion Research Allensbach. In October 2010, 1,786 face-to-face interviews by 420 interviewers were done. The majority of consumers (63?%) had never heard about boar taint. The level of knowledge of the existing practice of surgical castration to avoid boar taint is low in Germany (24?%). Vaccination of fattening boars to control boar taint is even less known (6?%). Participants were informed about the method of surgical castration and the vaccine method. Thereafter 41?% preferred the vaccine method over surgical castration (19?%). Interestingly, 40?% of the participants were not able to form an opinion which method to prefer. Overall, it can be concluded that the vaccination approach appears to be acceptable to consumers, if they are informed correctly.