Browsing by Author "Hoffman, Louwrens Christiaan"

Now showing 1 - 7 of 7
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    Application of fat-tailed sheep tail and backfat to develop novel warthog cabanossi with distinct sensory attributes
    (MDPI, 2020-12-08) Mahachi, Leo Nyikadzino; Rudman, Monlee; Arnaud, Elodie; Muchenje, Voster; Hoffman, Louwrens Christiaan
    This study compared the use of pork backfat (PF) and fat-tailed sheep tail and backfat (SF) on the physicochemical, fatty acids and sensory attributes of warthog cabanossi. There were no differences between weight loss during drying, moisture content, pH, water activity, salt content and lipid oxidation between the cabanossi types. However, protein and ash contents were higher in PF cabanossi whilst fat content was higher in SF cabanossi. The PF cabanossi had higher polyunsaturated fatty acids (especially n-6), lower monounsaturated fatty acids whilst the saturated fatty acid content was similar between the two cabanossi products. The n-3:n-6 ratio was more beneficial in the SF cabanossi. The descriptive sensory analysis showed two distinct products where PF cabanossi scored higher for most attributes. Although SF cabanossi scored less for these attributes, this cabanossi had unique and acceptable sensory attributes. This study concluded that fat-tailed sheep tail and backfat could be used to produce a unique cabanossi product of acceptable quality.
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    Die doeltreffendheid van sekere parameters ter bepaling van die weefselsamestelling van varkkarkasse
    (Stellenbosch : Stellenbosch University, 1987-11) Hoffman, Louwrens Christiaan; Vosloo, W. A.; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Science.
    INLEIDING: Van al die plaasdiere, is die vark die enigste spesie wat slegs vir vleisprodukte aangehou word. Alhoewel daar verskeie varkrasse in Suid-Afrika bemark word, word hierdie varke, ongeag die ras, hoofsaaklik in die vleisbedryf vir twee doeleindes aangewend. Die ligter varkkarkasse (karkasmassa onder 50kg word as vleisvarke, en die swaarder varkkarkasse (karkasmassa bo 50kg) word as spekvarke verwerk. In hierdie projek is die doeltreffendheid van verskeie karkaspararneters ondersoek en as onafhanklike veranderlikes, afsonderlik of in kombinasie, in lineêre regressievergelykings gebruik, om sodoende regressievergelykings te verkry wat 'n hoë voorspellingswaarde van die varkkarkassamestelling i.t.v. vleis, vet en been sowel as van die groothandelsnitopbrengs en -samestelling van die karkasse besit.
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    Effect of different combinations of freezing and thawing rates on the shelf-life and oxidative stability of ostrich moon steaks (M. Femorotibialis medius) under retail display conditions
    (MDPI, 2020) Leygonie, Coleen; Hoffman, Louwrens Christiaan
    The aim of this study was to investigate the interaction between different rates of freezing and thawing on whole ostrich moon steaks to establish a combination or singular main effect that minimises thaw loss and maximises the retail display shelf-life regarding moisture loss, colour, lipid oxidation and tenderness. Five characteristic freezing rates (FR: 1, 2, 4, 8, 24 h) were compared with five characteristic thawing rates (TR: 1.5, 3, 6.5, 14, 21 h) in a completely randomised block design. Moon steaks (M. femorotibialis medius) from 125 birds were randomly assigned to a specific treatment combination before being subjected (after thawing) to a 10-day chilled storage at 4 °C shelf-life trial. Thawing rate had no effect (p > 0.05) on any of the quality (colour, drip and cooking losses, shear force, 2-thiobarbituric acid (TBARS)) parameters whilst freezing rate and display time both had significant (p < 0.05) influences. Thaw loss was lowest (p < 0.05) for the FR_1h and FR_2h, followed by FR_4h, FR_8h and FR_24. The FR_1h had the highest (p < 0.05) drip and shear force values during display while the FR_2h and FR_8h had the highest rate of oxidation (TBARS and metmyoglobin formation). FR_24h had the second best (p < 0.05) colour retention after FR_4h and minimal package drip. Overall, FR_4h resulted in the best quality meat over the entire shelf-life with high bloom retention, low TBARS and shear force, and average thaw, drip and cooking loss.
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    Effects of honeybush (Cyclopia subternata) extract on physico-chemical, oxidative and sensory traits of typical Italian salami
    (Wiley, 2020-02-18) Smit, Paula; Cullere, Marco; Zotte, Antonella Dalle; Balzan, Stefania; Hoffman, Louwrens Christiaan; Novelli, Enrico
    Honeybush (Cyclopia subternata Vogel) is an indigenous South African shrub enjoyed as hot brewed tea. "Unfermented" honeybush is also a potential antioxidant bioactive extract for foodstuffs due to its polyphenol content. The effect of "unfermented" honeybush extract (Hob; 0.5%) was evaluated in typical Italian salami and compared with nitrate (Nit; 100 mg/kg) and a control (Ctl; without nitrate or honeybush). After 35 days of ripening, Hob had a higher (p < .01) water activity (0.928), compared with Ctl (0.923) and Nit (0.924). Final pH (5.35-5.24) was not affected by treatments. Lower lipid oxidation was observed in Hob and Nit treatments (p < .001) compared with Ctl. Internal color and odor intensity were similar among treatments. Salami with honeybush extract had less spontaneous outer surface mold growth whereas the Ctl showed intermediate growth (p < .05). Honeybush extract seems a promising natural ingredient with antioxidant action.
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    Inclusion of Hermetia illucens larvae reared on fish offal to the diet of broiler quails : effect on immunity and caecal microbial populations
    (Czech Academy of Agricultural Sciences, 2020-05-30) Pasotto, Daniela; Van Emmenes, Liesel; Cullere, Marco; Giaccone, Valerio; Pieterse, Elsje; Hoffman, Louwrens Christiaan; Zotte, Antonella Dalle
    Hermetia illucens (black soldier fly, BSF) larvae meal has shown to be a good protein source in monogastric animal diets, but published data regarding its immunomodulatory properties is limited. For this purpose, a study has been conducted to evaluate the effects of larvae meal on selected immune parameters and caecal bacterial counts of broiler quails. Hermetia illucens larvae were reared on two substrates (100% chicken feed, BSF-M, or 50% chicken feed + 50% fish offal, BSF-F) in order to manipulate the fatty acid profile of larvae meal by increasing the long-chain omega-3 (n-3) polyunsaturated fatty acids which are known for their immunomodulatory properties. For immunological purposes, a total of 60 birds were randomly allocated to three dietary treatment groups (n = 20/treatment): control quail diet (CON), or quail diets including 10% of BSF-F or BSF-M larvae meal. Blood was collected 27 and 37 days after the trial commenced to determine the humoral immune response, serum lysozyme concentrations, serum bactericidal activity and protein fractions of the serum. The dietary inclusion of BSF-M meal resulted in an increased secondary humoral immune response compared to the CON treatment group (P < 0.01). Quails in the BSF-F treatment had significantly higher serum lysozyme activity compared to quails in the CON and BSF-M treatment group. Both larvae meals significantly increased cell-mediated immunity on day 37 (P < 0.001) but they had no effect on serum bactericidal activity. Both larvae meal sources resulted in higher α2-globulin levels on both sampling days, whereas γ-globulin levels were significantly lower in quails with the BSF-F treatment on day 27. Dietary treatments had no significant effect on caecal bacterial counts. In conclusion, the present study showed that the larvae meal had immunostimulatory effects in quails, but the rearing substrate of larvae strongly influenced the immunostimulatory properties of the larvae meal.
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    A preliminary study : antibiotic resistance patterns of escherichia coli and enterococcus species from wildlife species subjected to supplementary feeding on various South African farms
    (MDPI, 2020-02-28) Van den Honert, Michaela Sannettha; Gouws, Pieter Andries; Hoffman, Louwrens Christiaan
    Studies have shown that antibiotic resistance among wild animals is becoming a public health concern, owing to increased contact and co-habitation with domestic animals that, in turn, results in increased human contact, indirectly and directly. This type of farming practice intensifies the likelihood of antibiotic resistant traits in microorganisms transferring between ecosystems which are linked via various transfer vectors, such as rivers and birds. This study aimed to determine whether the practice of wildlife supplementary feeding could have an influence on the antibiotic resistance of the bacteria harboured by the supplementary fed wildlife, and thus play a potential role in the dissemination of antibiotic resistance throughout nature. Escherichia coli and Enterococcus were isolated from the faeces of various wildlife species from seven different farms across South Africa. The Kirby-Bauer disk diffusion method was used according to the Clinical and Laboratory Standards Institute 2018 guidelines. The E. coli (F: 57%; N = 75% susceptible) and Enterococcus (F: 67%; N = 78% susceptible) isolates from the supplementary fed (F) wildlife were in general, found to be more frequently resistant to the selection of antibiotics than from those which were not supplementary fed (N), particularly towards tetracycline (E. coli F: 56%; N: 71%/Enterococcus F: 53%; N: 89% susceptible), ampicillin (F: 82%; N = 95% susceptible) and sulphafurazole (F: 68%; N = 98% susceptible). Interestingly, high resistance towards streptomycin was observed in the bacteria from both the supplementary fed (7% susceptible) and non-supplementary fed (6% susceptible) wildlife isolates. No resistance was found towards chloramphenicol and ceftazidime.
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    Slaughter characteristics of feedlot-finished premium South African lamb : effects of sex and breed type
    (MDPI, 2020-05-18) Van Der Merwe, Daniel Andre; Brand, Tertius Swanepoel; Hoffman, Louwrens Christiaan
    This study compared the carcass characteristics of ram and ewe lambs from South African wool, dual-purpose, meat, and fat-tailed sheep types, reared to produce premium lamb carcasses. The lambs were reared on a feedlot diet (10.41 MJ ME/kg feed and 19.06% crude protein) from weaning (30 kg live weight) until they attained a back-fat depth of ~4 mm, measured using ultrasound. After slaughter, the carcasses were assessed for retail cut yields, composition, and physical meat quality. Later, maturing lambs attained heavier carcass weights than early maturing breeds (~20.7 kg vs. 16.9 kg, respectively; p ≤ 0.05), and differences in carcass composition and retail cut yields were ascribed to differences in the frame size and pattern of fat deposition of the respective breeds. Small differences in physical meat quality were observed, with meat from Dormer and Namaqua lambs having notably higher shear-force values (~46 N) than that from Meatmaster carcasses (~34 N). These differences though are expected to have little influence on the perceived quality of the meat.