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Title:Evaluating lipid oxidation and sensory characteristics in bacon from immunologically castrated barrows
Author(s):Herrick, Ryan
Advisor(s):Dilger, Anna C.
Department / Program:Animal Sciences
Discipline:Animal Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
Degree:M.S.
Genre:Thesis
Subject(s):Bacon
Immunological castration
Improvest
Lipid oxidation
Abstract:With increased time after immunological castration, lipid content of bacon increases and unsaturated fatty acid content is reduced. Our objective was to determine the effect of immunological castration (Improvest®, gonadotropin releasing factor analog-diphtheria toxoid conjugate, Zoetis) management strategies [age of slaughter, and time after second dose (ASD)], on lipid oxidation and sensory characteristics of bacon packaged under simulated food service conditions. To mimic conditions of a normal production system, all bellies from immunological castrated (IC) barrows were pooled to compare bacon from IC barrows, regardless of management strategy, to physical castrated (PC) barrows and gilts for the same traits. Bellies (N=129) from two slaughter dates were manufactured into bacon under commercial conditions. Immunological castration management strategies included 24 wk old IC pigs 4, 6, 8, or 10 wk ASD, 26 wk old IC pigs 6 wk ASD and 28 wk old IC pigs 8 wk ASD. Gilts and PC barrows were slaughtered at 24, 26, and 28 wk of age and pooled across age. Center-cut bacon was laid-out on parchment paper, packaged in oxygen-permeable poly-vinyl lined boxes, and frozen (-33°C) for 1, 4, 8, or 12 wks to simulate food service conditions. At the end of each storage period, trained sensory panelists evaluated bacon for saltiness, oxidized odor, oxidized flavor, and off flavor on a 15-cm line scale (0 cm indicated none and 15 cm indicated extreme intensity for each characteristic). At similar time points, lipid oxidation (TBARS) and proximate analysis were determined. Both data sets (IC management strategies and IC barrows compared with PC barrows and gilts) were analyzed using the MIXED procedure in SAS with belly as the experimental unit. Model included fixed effects of treatment, wk of storage, their interaction, and blocked by kill date. In both data sets, least square means were separated using the PDIFF option with a Tukey-Kramer adjustment. Overall, as storage time increased, saltiness decreased from 1 to 12 wks (P < 0.01), oxidized odor and oxidized flavor increased (P < 0.01), and TBARS increased by 0.23-0.30 mg MDA/kg meat from 1 to 12 wks (P < 0.01). Moisture and lipid content did not change with storage (P ≥ 0.11). There was no interaction of treatment and wk within IC treatments or within sex classes (P ≥ 0.11). Oxidized odor and flavor were unaffected by immunological castration management strategy (P > 0.21) or sex class (P > 0.31). Among bacon from IC barrows, TBARS were increased in bacon from IC barrows slaughtered at 28 wk of age, 8 wks ASD compared with bacon from IC barrows slaughtered at 24 wk of age, both 4 and 6 wks ASD (P < 0.01), with other treatments being similar to both extremes. Lipid content was increased and moisture reduced (P < 0.01) in bacon from IC barrows 8 and 10 wks ASD compared with IC pigs at 4 and 6 wks ASD, regardless of age at slaughter. When bacon from IC treatments were pooled, TBARS tended to be increased (P = 0.06) by 0.03 mg MDA/kg meat from IC barrows compared to gilts, with bacon from PC barrows not differing from either sex. Bacon from PC barrows contained less (P < 0.01) moisture and more (P < 0.01) lipid than bacon from IC barrows and gilts. Bacon from IC barrows and gilts had similar lipid and moisture content (P > 0.05). Regardless of immunological castration management strategy or sex, bacon became more oxidized with storage. Within IC treatments, lipid oxidation increased as storage time increased, and lipid content was increased in barrows 8 and 10 wks ASD, regardless of age at slaughter. Bacon from IC barrows was more oxidized than bacon from PC barrows, but was similar to bacon from gilts. However, regardless of treatment, there were no differences in sensory attributes of bacon, and after 12 wks of frozen storage bacon did not become rancid. Therefore, using bellies from Improvest® managed pigs for bacon should not result in reductions in shelf life.
Issue Date:2014-09-16
URI:http://hdl.handle.net/2142/50753
Rights Information:Copyright 2014 Ryan Herrick
Date Available in IDEALS:2014-09-16
Date Deposited:2014-08


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