Principles of Meat Science provides a comprehensive overview that includes the latest discoveries and principles that are necessary to understand the science of meat and the utilization of meat as food.
The Science of Poultry and Meat Processing is a free textbook by Dr.Shai Barbut, a faculty member in the Food Science Department at theUniversity of Guelph, Canada. The book is available for download here. Thanks to a translation by Michelle Snoeijenbos, the book is now also available in Spanish.
principles of meat science ebook free download
The modern meat industry uses machine vision, robots, and integratedprocessing lines to enhance speed, efficiency and sanitation. Forexample, hundreds of identical nuggets are produced, every minute,without the touch of a human hand. The whole process is often fullyautomated and continues into batter and breading, par frying andfreezing.
The use of large scale processing equipment requires good understandingof meat science principles. In the book you will find description ofequipment used for primary and further processing with emphasis on theprinciples of operation and line integration. Many full-color picturesand illustrations are provided.
Principles of Meat Science provides a comprehensive overview that includes the latest discoveries and principles that are necessary to understand the science of meat and the utilization of meat as food.
Among the oxidation-induced factors for instance, lights (e.g., ultraviolet) is thought to be thermodynamically capable of production of free radicals directly in lipids, the principles of light-absorbing groups of lipids are double bonds, peroxide bonds and carbonyls which subsequently under the other steps to generate volatiles. And other factors such as oxygen, lypoxygenase, metals and etc which all also affect the lipid oxidation however that is another concern, in the present work we only consider on the heat effect that similar to cooking condition to induce the oxidation and degradation of fatty acids in producing volatile flavor compounds of cooked meat. The degrees of heating temperatures have been reported to affect variously lipid oxidation, in that high heating temperatures (e.g., frying, roasting) can have highly sufficient energies to break the single bonds (e.g., C-C or C-H) in the acyl back bonds to generate a lot of lipid alkyl radicals that participate the radical chain formation of oxidation [58]. Lower heating temperatures have lower energies which can break O-O bonds in traces of ROOH. Mottram (1985) [59] also stated that meat is cooked under boiled and lightly roasted conditions, lipid oxidation products dominated the detected compounds, and many of among them such as aldehydes, alcohols, ketones and lactones which have sufficiently low odor threshold to be contributors of meat aroma flavors.
In general, in Maillard reaction mixtures containing lipids produce a lot of lipids-derived volatile compounds such as aldehydes, furans, hydrocarbons, alcohols and ketones. Furthermore, the reaction mixtures also containing the Maillard products such as H2S, NH3, etc. Which all are able to interact with each other to form new heterocyclic aroma volatile compounds as the consequences of the interactions between lipids with Maillard products. The most abundant compounds have been detected as results of the interactions are thiophene class such as 2-pentylthiophene, 2-hexylthiophene and thiol class such as 2-thiophenethiol, 2-furylmethanethiol, 2-methyl-3-furanthiol and etc [38, 61]. A recent study by Elmore and colleagues (2002) [34] concluded that breakdown products of polyunsaturated fatty acids especially are n-3 acids have a shorter chain length have lower odor thresholds will also be present at relatively high concentrations and are more reactive. These breakdown products will affect meat flavor by interacting with the Maillard reaction reducing levels of meaty aroma compounds, such as sulfur-substituted thiophenes and furans. As n-3 PUFAs are readily oxidized, they could initiate the free radical oxidation of more saturated acids, increasing levels of breakdown products of n-6 and n-9 fatty acids, which may also alter the aroma compounds of the cooked meat.
Irradiation is a food safety technology designed to eliminate disease-causing germs from foods. Depending on the dose levels of irradiation applying on the raw meat and poultry, or ready-to-eat meats that can eliminate bacteria commonly found such as E. coli, Salmonella and Listeria; virus; or parasites. However, irradiation may result in off-odors and flavors. The odors vary with the type of meat, temperature during irradiation, oxygen exposure during and/or after the irradiation process, packaging and presence of antioxidative substances [104]. Most of studies have reported that the aroma flavors of irradiated meat associated with rotten egg, sweet, bloody, cooked meat, barbecued corn, burnt, sulfur, metallic, alcohol, acetic acid, liver-like serumy and bloody [105, 106, 107]. Irradiation can initiate or promote lipid oxidation resulting in undesirable off-odors and flavors [108, 109]. Jo and Ahn, (2000) [110] showed that reactions of sulfur-containing amino acids with radiolytic products of water appear to be the source of hydrogen sulfide and other volatile sulfur-containing compounds which contribute to off-flavor. On the other hand, irradiation may result in the formation of free radicals from unsaturated fatty acids at double bond positions [109]. An increase in lipid peroxidation products such as hexanal and (E)-4,5-epoxy-(E)-2-decenal in combination with a loss of desirable meaty odorants (4-hydroxy-2,5-dimethyl-3(2H)-furanone and 3-hydroxy-4,5-dimethyl-2(5H)-furanone) result in development of warmed over flavor of cooked, refrigerated beef [16]. However, the effects of irradiation on aroma flavors are also depended on: (1) Dose levels of irradiation, it has been demonstrated that the dose levels of irradiation influence variedly on volatile flavor components of cooked meat, as reported by Jo and Ahn (2000) [110] who indicated some of hydrocarbons included 1-heptene and 1-nonene increased with irradiation dose immediately after irradiation of beef. A similar observation also was reported by Yong et al (2000) [111] who indicated that among the 150 flavor compounds indentified in beef the cyclodecene, (E)-2-hexenal, nonene and 2-nonenal showed an increase in a dose-dependent fashion. For the effect of irradiation on chicken flavors, Yong e al (2000) [112] showed that among the 129 identified volatile flavor compounds the cyclotetradecene, 2-methylpentanal and 4-methylcyclohexene were formed specifically in response to irradiation, and level of cyclotetradecene increased in a dose-dependent fashion; (2) Oxygen presence, the presence of oxygen around meats during irradiating can diffuse into the meats, and then results in radiolytic changes which precipitate oxidation and unacceptable secondary breakdown products. As well known, lipid oxidation needs oxygen presence to produce oxidized-products such as aldehydes, Nam and Ahn (2003) [113] indicated that irradiation of meat in aerobic packaging promoted production of aldehydes such as propanal and hexanal which is assumed as a good indicator of lipid oxidation. The similar observation also was reported by Nam et al (2001) [114] who also showed that irradiation increased TBARS values and off-flavor in aerobically-packaged pork (3) Temperature effect, temperature during irradiating meats has a large effect on aroma flavors of irradiated meat because temperature affects what radiolytic products are formed and what ratios [104]. Using lower temperature during irradiation of meat by freezing meat before irradiation can reduce detrimental effects via retarding autoxidation and extending shelf life; (4) pH effect, it has also been demonstrated that the ultimate pH of meat at the time of irradiation influences lipid oxidation. Nam et al (2001) [114] recently showed that irradiation increased lipid oxidation of normal and pale-soft-exudative (low pH group) muscles, whereas dark-firm-dry (high pH group) muscle was very stable and resistant to oxidative changes. Therefore, to minimize the detrimental effects of irradiation on aroma flavor characteristics we can modify atmosphere packaging by using vacuum packaging (anaerobic packaging) or replacement with inert gases (i.e. nitrogen, helium, hydrogen, carbon dioxide) to eliminate oxygen. Reducing the temperature (freezing) prior to irradiation and addition of antioxidants. Vacuum packaging retains irradiation-generated sulfur-containing compounds, however re-packaging meat in oxygen-permeable materials allows for dissipation of these flavor compounds.
In order to have a cooked meat product with its desirable aroma flavors as expectation of consumer, it is important to understand how aroma flavors are derived, the mechanisms by which flavor components are generated, and the factors affect formation of flavor compounds then determine the final aroma flavor characteristics of cooked meat. Regarding the effects of factors on aroma flavors of cooked meat and to minimize the detrimental effects it is suggested if increasing the polyunsaturated fatty acids (e.g. C18:3n-3, DHA, EPA) to increase nutritional benefits to the consumer by using fat-supplemented diets however the undesirable flavors may result. Because the breakdown products of these fatty acids have a shorter chain length therefore are more volatile and they affect meat flavors by interacting with the Maillard reaction results in reducing levels of meaty aroma compounds such as sulfur-substituted thiophenes. Therefore, diets, feeding regimes, welfare and management of animals should be taken into account. Cooking conditions such as temperature, holding time and cooking methods play an important role in determining the formation volatile flavor compounds. In general, it has been demonstrated that cooking meat at high temperature (by roasting, grilling) will produce better aroma flavor characteristics due to the important Maillard products are formed. In addition to the cooking effect, it is suggested that a slow cooking and longer hold time can allow the undesirable volatile flavor compounds to dissipate, thus reduce warm-off flavor. Irradiation of meat can eliminate pathogens however, off-flavor may result therefore, and to minimize the detrimental effect of this method we can lower temperature during irradiation of meat by freezing meat before irradiation. Modifying atmosphere packaging by using vacuum packaging (anaerobic packaging) or replacement with inert gases (i.e. nitrogen, helium, hydrogen, carbon dioxide) to eliminate oxygen in meat during irradiation are also the alternatives. Chiller ageing of meat should be applied to improve eating quality however should not age for a long time (3 week period in maximum is encouraged) because chiller ageing meat for a too long period may result in flavor deterioration and decreasing desirable flavors.
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