Virginia C. Resconi

Sensory evaluation of castrated lambs finished on different proportions of pasture and concentrate feeding systems

Castrated male Corriedale lambs from Uruguay were finished under one of four feeding systems, which differed in the level of pasture and the amount of concentrates. Treatment 1 (T(1)) was all pasture (P), T(2) was P plus concentrate (C; 0.6% of live weight [LW]), T(3) was P+C (1.2% of LW), and T(4) was C plus alfalfa hay as a source of fibre (both ad libitum). A trained taste panel analysed samples from 96 lambs, using a quantitative descriptive method in a complete and balanced design. Eight of the 11 sensory attributes were affected by Treatment (p<0.05). The inclusion of concentrate in the lamb diet improved the sensory quality of the meat, being related to its effect on lowering the intensity of undesirable odours and flavours (strange, rancid and acid), generating higher intensity of typical lamb aromas as well as producing higher tenderness. The frequencies of odour/flavour unsolicited observations also showed disadvantages to pasture feeding. Lambs fed only concentrates (T(4)) produced meat that had the highest fat flavour intensity and the best overall acceptability given by the panellists.

Relationship between odour-active compounds and flavour perception in meat from lambs fed different diets

To identify the most important aroma compounds in 20d-aged meat from castrated heavy Corriedale lambs fed one of four diets, grilled loin samples were subjected to a dynamic headspace-solid phase extraction (DHS-SPE) and gas chromatography-olfactometry (GC-O). Most of the important odorants were aldehydes and ketones. To evaluate the effect of finishing diet on carbonyl compounds, a derivatization of the headspace carbonyls using o-[(2,3,4,5,6-pentafluorophenyl)methyl]hydroxylamine hydrochloride (PFBHA) and analysis by GC-MS was conducted. Diet did not affect aliphatic saturated aldehydes. The meat from lambs finished on pastures, without a concentrate supplement, had very low concentrations of lipid-derived unsaturated aldehydes and ketones and Strecker aldehydes, possibly because of the protective effect of antioxidants that occur in the diet naturally. Lamb flavour was related to the concentration of heptan-2-one and oct-1-en-3-one, but rancid or undesirable flavours were not related to the abundance of carbonyl compounds.

The Development of Aromas in Ruminant Meat

This review provides an update on our understanding of the chemical reactions (lipid oxidation, Strecker and Maillard reactions, thiamine degradation) and a discussion of the principal aroma compounds derived from those reaction or other sources in cooked meat, mainly focused on ruminant species. This knowledge is essential in order to understand, control, and improve the quality of food products. More studies are necessary to fully understand the role of each compound in the overall cooked meat flavour and their possible effect in consumer acceptability.

Color, Lipid Oxidation, Sensory Quality, and Aroma Compounds of Beef Steaks Displayed under Different Levels of Oxygen in a Modified Atmosphere Package

UNLABELLED High oxygen modified atmosphere packaging (MAP) is currently used by the industry to maintain an attractive color in fresh meat. However, it can also promote lipid oxidation and sensory changes. The aim of this study was to compare the quality of beef steaks displayed under different levels of oxygen. For that purpose, meat was stored with 50%, 60%, and 80% of oxygen for 4 and 8 d at retail conditions. A control treatment with steaks vacuum packaged, without exposure to retail display, was included, and color, lipid oxidation, organoleptic characteristics, and aroma compounds were analyzed. Steaks displayed under high oxygen MAP with 50% of oxygen showed the lowest color stability, according to hue values. Higher oxygen levels did not necessarily correspond with higher rancidity levels in the raw meat. Thiobarbituric Acid Reacting Substances (TBARS) values were higher than 2.2 mg malonaldehyde (MDA)/kg muscle in all the samples displayed for 8 d at retail conditions. These samples exhibited the highest intensities of rancid and the least intense beef odors and flavors. The ketones: 2,3-butanedione, 2-octanone, 2,3-pentanedione, 2-heptanone, 4-methyl-2-pentanone, and the aldehydes: pentanal, 2-methyl-butanal, and 2-furfurylthiol, 1-octen-3-ol and 2-methylpropyl-acetate, were proposed as candidates for the aroma differences between the cooked beef steaks stored under vacuum and high oxygen packs. PRACTICAL APPLICATION High oxygen modified atmosphere packaging (MAP) is used to increase shelf-life and color at the retail level. However, oxygen deteriorates faster some quality attributes, being a contributor to lipid oxidation that could be perceived at consumption. This study attempts to find the best gas composition in a MAP in order to maintain the color, minimizing the oxidation. Aromatically relevant chemicals have been analyzed by gas olfactometry-gas chromatography as a key to measure beef oxidation after display.

Sensory quality of beef from different finishing diets

Beef production under different local husbandry systems might have meat sensory quality implications for the marketing of these products abroad. In order to assess the effect of finishing diet systems on beef quality, a trained sensory taste panel assessed meat aged for 20 days from 80 Uruguayan Hereford steers that were finished on one of the following diets: T1=Pasture [4% of animal live weight (LW)], T2=Pasture [3% LW plus concentrate (0.6% LW)], T3=Pasture [3% LW plus concentrate (1.2% LW)], or T4=Concentrate plus hay ad libitum. Beef odour and flavour intensities decreased with an increase in the energy content of the diet. The meat from T2 had the lowest acid flavour and strange odours intensities. In general, steers fed only concentrate plus hay (T4) produced meat that had an inferior sensory quality because they had more pronounced off-flavours and was tougher.

Modelling the influence of inulin as a fat substitute in comminuted meat products on their physico-chemical characteristics and eating quality using a mixture design approach.

The effects of fat substitution using two commercial inulin products on the physico-chemical properties and eating quality of a comminuted meat product (breakfast sausage) were modelled using a specialised response surface experiment specially developed for mixtures. 17 treatments were assigned representing a different substitution level for fat with inulin. Sausages were formulated to contain pork shoulder, back fat/inulin, water, rusk and seasoning (44.3, 18.7, 27.5, 7 and 2.5% w/w). Composition, sensory, instrumental texture and colour characteristics were assessed. Fructan analysis showed that inulin was unaffected by heat or processing treatments. Models showed increasing inulin inclusions decreased cook loss (p<0.0017) and improved emulsion stability (p<0.0001) but also resulted in greater textural and eating quality modification of sausages. Hardness values increased (p<0.0001) with increasing inulin concentration, with panellists also scoring products containing inulin as less tender (p<0.0112). Optimisation predicted two acceptable sausage formulations with significantly lower fat levels than the control, which would contain sufficient inulin to deliver a prebiotic health effect.

Gas Chromatographic-Olfactometric Aroma Profile and Quantitative Analysis of Volatile Carbonyls of Grilled Beef from Different Finishing Feed Systems

UNLABELLED In this study, the important odor impact volatiles generated in the meat of grilled beef loin muscle were characterized. Animals were finished in 4 different diet systems: T₁, pasture (a mixture of Medicago sativa, Trifolium repens, and Festuca arundinacea); T₂, pasture supplemented with cracked corn grain (offered at 0.6% live weight, LW); T₃, pasture supplemented with cracked corn grain (offered at 1.2% LW); and T₄, concentrate (pellets with 85% corn and 12.8% sunflower, on a dry-matter basis) plus alfalfa hay (both ad libitum). Aroma compounds were assessed by dynamic headspace-solid phase extraction (DHS-SPE) and gas chromatographic-olfactometric (GC-O) analysis. Most odorants were carbonyl compounds, some of them reaching high GC-O scores, especially 1-octen-3-one, (E)-2-octenal, methional, and hexanal. A specific quantitative analysis of ketones and aldehydes was conducted through their derivatization with o-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine hydrochloride directly on the headspace trap and analyzed by GC-MS, with the purpose of studying the effect of finishing diet systems. From the 23 carbonyl compounds quantified, 2 were especially affected by the diet system; methional was higher in the treatment based on concentrates, whereas (E,E)-2,4-heptadienal was higher in the treatment based only in pastures. The results are discussed considering previous published productive and quality traits. PRACTICAL APPLICATION The knowledge of how production factors, such as animal feeding, can affect the flavor of meat is of significant interest toward in achieving a high-quality and differentiated product. The development of more specific and efficient methodologies is necessary to analyze meat aroma compounds, which would be used as routine analysis, that is for product authentication. In the future, the use of this analysis would allow producing and designing specific foods according to different markets.

The effect of partial-fat substitutions with encapsulated and unencapsulated fish oils on the technological and eating quality of beef burgers over storage

The effects of fat substitution (≤ 15%) with commercial encapsulated and unencapsulated fish oils on the technological and eating quality of beef burgers over storage [modified atmosphere packs (80% O2:20% CO2); constantly illuminated retail display at 4 °C; for 15 days] were studied using design of experiment (DOE). Burger formulations comprised beef shin (59.5%), salt (0.5%), vitamin E (0.015%) combined with varying levels of beef-fat/fish oils depending on the treatment. Increasing amounts of encapsulated and unencapsulated fish oils in burgers increased polyunsaturated fatty acid content (P < 0.001). Storage decreased (P < 0.001) a* values, which was in agreement with oxymyoglobin data. Vitamin E inclusion in burgers resulted in higher (P < 0.01) oxymyoglobin values. TBARS values increased (P < 0.001) over storage as expected. Fat substitution with unencapsulated oils increased cook loss (P < 0.001) and decreased hardness (P < 0.05) compared to other treatments. Optimisation predicted a burger formulation with 7.8% substitution in beef-fat with encapsulated fish oil. Panellists scored the optimised burger formulation (P < 0.05) lower than controls for overall acceptability.

Beef quality attributes: A systematic review of consumer perspectives

Informed by quality theory, this systematic literature review seeks to determine the relative importance of beef quality attributes from a consumer perspective, considering search, experience and credence quality attributes. While little change is anticipated in consumer ranking of search and experience attributes in the future, movement is expected in terms of ranking within the credence category and also in terms of the ranking of credence attributes overall. This highlights an opportunity for quality assurance schemes (QAS) to become more consumer focused through including a wider range of credence attributes. To capitalise on this opportunity, the meat industry should actively anticipate new relevant credence attributes and researchers need to develop new or better methods to measure them. This review attempts to identify the most relevant quality attributes in beef that may be considered in future iterations of QAS, to increase consumer satisfaction and, potentially, to increase returns to industry.

The effects of potato and rice starch as substitutes for phosphate in and degree of comminution on the technological, instrumental and sensory characteristics of restructured ham

The effects of sodium tripolyphosphate (STPP), two sources of starch (potato starch: PS and rice starch: RS) and comminution degree (CD) on the technological, instrumental and sensory characteristics of reformed hams were studied using response surface methodology. Both starches reduced cook loss and decreased ham flavour intensity, but RS had stronger effects on instrumental measures of texture, while PS was associated with improved juiciness when low/no added STPP was included. Coarsely ground meat, processed 100% with the kidney plate was associated with slightly increased cook loss, reduced texture profile analysis parameters and a more intense ham flavour compared to the other treatment (80% ground with a kidney plate plus 20% with a 9mm plate). STPP was the sole factor affecting overall liking. If starch is included in the formulation, the standard level of STPP (0.3%) can be reduced by half with no increase in cook losses, but some decline in sensory quality cannot be avoided.