MANUAL DE LABORATORIO PARA BIOQUíMICA GENERAL DEL INGENIERO AGRóNOMO FITOTECNISTA

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Carbohidratos. Estructura Y CLASIFICACIóN

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MANUAL DE PRáCTICAS DE LABORATORIO DE QUíMICA AGRíCOLA Plan de Estudios IAI-F15

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Evaluation of physico-chemical and microbiological quality of sheep meat in the central higlands of Mèxico

In order to develop a microbiological starting point for sheep meat production from Central Highlands of Mexico, the aim of the current research was to evaluate their microbiological and physico-chemical quality from slaughterhouses. Carcasses, utensils and workers’ hands samples were taken according to NOM 092-SSA1-1994, Official Chilean Standard NCh-ISO 17025 of 2005, NF V08-060 Microbiology of food and animal feedings stuffs and European Union Council and Parliament Regulations. The microbiological quality was analyzed by Mesophilic Aerobic, Total Coliforms and Fecal Coliforms values. Most of the slaughterhouses were close to the Superior Limit Permitted (MLP) for Mesophilic Aerobic values (3, 59 log10 UFC/mL) on sheep carcasses. Even though there were no fecal coliforms found on sheep carcasses, they have been found on knives, tables and workers’ hands in most of the slaughterhouses. In the physico-chemical variables initial and ultimate pH (45 min and 24 h), initial and ultimate temperature (45 min and 24 h), lightness (L*), redness (a*), yellowness (b*) and tenderness were evaluated and there were significant differences among variables except for initial Temperature (p ≤ 0.05). In conclusion, although the physico-chemical characteristics were acceptable the Microbiological values overpass the MLP for Mesophilic Aerobic and Fecal Coliform haven’t been found any correlation between both of them at the analyst moment. However, because of the high sheep meat production in the Central Highlands of Mexico and these microbiological characteristics it has been concluded that is required a shared responsibility among the productive sector and from the government in order to regulate that production

Frying edible vegetable oil quality from street-food vendors in a Metropolitan area in the Central Highlands of Mexico

Vegetable oil deterioration during frying is a health problem because of oil degradation compounds and recycled oil practices are related to disturb oil quality. Frying food street-vendors are an important part of endemic market type Tianguis at the Metropolitan areas in the Central Highlands of Mexico. The main objective of this research was to evaluate frying edible vegetable oil quality from frying by street-food vendors in a Metropolitan area in the Central Highlands of Mexico. A behaviour questionary registered fresh and recycling oil addition, frying temperature and method in real operation conditions for three working days. Free fatty acid, colour, p-Anisidine, peroxide, and TOTOX indexes were observed in the vendors by triplicate. Free fatty acids and peroxide values in two vendors exceeded the NMX-F-223-SCFI-2011 values. Physicochemical variables revealed oil oxidation deterioration. Not so high temperatures were registered, and continually fresh oil addition was suggested as mitigating or masking edible oil of thermal oxidation and its degradation agents during the observed time. Thermal oxidation could be lower than in controlled conditions as in many reports due to vendor operations studied as a real approximation that suggested less oil degradation. Present results could be evidence for government intervention in the regulation needsCONACY

In vitro gas production of five rations of different maize silage and concentrate ratios influenced by increasing levels of chemically characterized extract of Salix babylonica

Salix babylonica (SB) is a tree of the willow family with slender leaves, native to dry areas of northern China. Trees of SB are commonly found along moist places and are often planted or cultivated as an ornamental tree. SB often cultivated to make high-quality wood chips, a renewable and carbon-neutral energy source. It was introduced to Mexico and many other countries other than China (1). Most of the members of the genus Salix were analyzed for their flavonoid, terpenoid, and phenolic constituents with diverse and important biological activities of improving ruminal fermentation (2). SB naturally contains benzyl ester of gentisic acid 2′-O-acetyl β-d-glucoside, along with trichocarpin, salicin, kaempferol-7-O-glucoside, apigenin- 7-O-galactoside, and luteolin-4′-O-glucoside compounds and an ester of terephthalic acid (2). However, willows have phenolic glycosidic compounds based on the structure of salicin (3). Moreover, three flavonoids compounds were extracted from SB and identified as luteolin-7-O-β-Dglucopyranoside, luteolin, and chrysoeriol (2).This study was carried out to assess the effect of the chemical substances of Salix babylonica (SB) extract on in vitro rumen fermentation of five mixed rations with different maize silage to concentrate ratios. Fifty-nine compounds were identified in SB extract using the retention time and mass spectral technique. Interactive effects were noted (P < 0.001) for the asymptotic gas production (GP) (b), the rate of production (c), the initial delay before GP begins (L), pH, dry matter digestibility, metabolizable energy (ME), organic matter digestibility (OMD), short chain fatty acids (SCFAs), gas yield at 24 h (GY24), microbial crude protein, and in vitro GP. Both 1.2 and 1.8 mL SB/g DM had the highest (P < 0.05) b and c values. Addition of 1.2 and 1.8 mL SB/g DM linearly improved (P < 0.001) ME, OMD, SCFAs, and GY24. It could be concluded that, based on the highly detected interaction effects between ration types and extract doses for fermentation parameters and GP, the most effective dose of SB varied between incubated total mixed rations. However, the ration of 25% silage and 75% concentrate had the highest nutritive value, especially at doses of 1.2 to 1.8 mL SB/g DM total mixed ration

Physicochemical characteristics that influence the meat pork quality in supermarkets in the central highlands of Mexico

Twenty-two supermarkets in the Central Highlands of Mexico were sampled in order to classify them and to compare their pork meat quality based on its physicochemical characteristics. The supermarkets were classified in three types in accordance with socioeconomic status of buyers as low, medium, and high. Methods: Samples were obtained from the Longissimus dorsi muscle from 10th to 12th ribs. Results: Objective color was L* 46.97, a* 6.22 and b* 5.1. Subjective color indicated that it was red with a value of 3.06, subjective marbling was 2.8 %, and objective value was 2.9 %. Moisture varied from 690 to 739.3 g/kg, protein varied from 205.5 g/kg to 229. 6 g/kg and shear force (SF) was 2.87 kg/cm2 . There were no significant differences (P≥0.05) between the variables besides subjective marbling. Tukey´s test indicated that the lowest average included low and medium socioeconomic status supermarkets, which means that the fat content found in the chop eye is less than in meat in high socioeconomic level supermarkets. Conclusions and recommendations: According to the results, pork sold in the supermarkets in the Central Highlands of Mexico was a tender meat with reddish pink color, firm texture and little exudation and with an appropriate protein and intramuscular fat contents

Potential of Triticale (X Triticosecale Wittmack) Malts for Beer Wort Production

Artículo CientíficoTriticale grain, a wheat-rye hybrid mostly used for animal feed, has been recently reported to exhibit different trends when used as unmalted or malted grain in the brewing industry. The aim of this study was to evaluate the potential of four different triticale lines to evaluate their potential for malt production. The four studied triticale malts PM-1, PM-3, PM-6, and PM-8 lines yielded an extract content higher than 100% and a diastatic power similar to some barley malts (86.19–190.19 L). The produced worts showed a higher percentage of soluble protein, between 4.56% and 5.66%, with a large viscosity value ( 2.055cP) reported for this raw material. Two triticale malts were selected based on their performance, PM-1 and PM-3, and fermented at different percentage combinations with barley malt (0, 30, 50, 70, and 100%). The results revealed that the use of 100% triticale malt yielded an acceptable fermentation, with an Apparent Attenuation Limit (AAL) of 72%. The optimal triticale-barley malt ratio was 30/70, where supplementing triticale malt enriched the extract, enhancing the fermentation. These results support the suitability and possible establishment of triticale grain as a brewing crop.PCARN/UAEMe

Ethanol and aqueous extracts characterization from guava (Psidium guajava L.) and avocado (Persea americana Mill.) residues

Artículo científicoIn Mexico, avocado and guava production generate agronomic residues that contain bioactive compounds as secondary metabolites produced in plants. Their consumption offer favourable health effects; therefore, the objective of the present research was to characterize the bioactive compounds and antioxidant properties in guava (Psidium guajava L.) and avocado (Persea americana Mill.) residues (pulp or epicarp and leaves) at different ethanol concentrations (T1 100%, T2 75%, T3 50% and T4 25%, v/v) and in aqueous extracts (T5). Avocado epicarp (56.17 mg of EAG g-1 dm) and guava leaves 50% extracts (45.13 mg of EAG g-1 dm) presented the highest total phenol content; consequently, as it was expected avocado epicarp (328.95 TEAC/g dm) and guava leaves 25% extracts (320.01 TEAC/g dm) shown the highest antioxidant capacity. On the other hand, the highest saponins values were at avocado (100.60 mg g-1 dm) and guava leaves (76.96 mg g-1 dm) 25% extracts. Then avocado epicarp and guava leaves extracts are suggested as a high potential for agro-industrial, pharmacological and chemical uses.UAEMe

Effect of organic selenium-enriched yeast supplementation in finishing sheep diet on carcasses microbiological contamination and meat physical characteristics

The aim of the current study was to evaluate the effect of feeding Pelibuey sheep on diet supplemented with different doses of organic selenium (Se)-enriched yeast on carcasses microbiological contamination and meat physical characteristics. The experiment was conducted during the finishing stage of 18 female sheep and lasted for 60 days. In a complete randomized design, sheep were distributed to one of three treatments: the control without Se-yeast (T1), the control supplemented with Se-yeast at 0.35 mg Se/kg DM (T2), and control supplemented with Se-yeast at 0.60 mg Se/kg DM (T3). The yeast product used was Selyeast 3000TM yeast (LFA Lesaffre, Toluca, Mexico) with a Se concentration of 3000 ppm (mg/kg). Lambs were slaughtered at the end of the experiment at an average weight of 39.5±4.41 kg and samples were taken for microbiological analysis. There were no differences between treatments (P>0.05) and the aerobic plate counts for T1, T2 and T3 had indexes of 0.10, 0.08 and 0.08 log10 CFU/cm2 , respectively. Total coliform counts obtained were 0.13, 0.10 and 0.09 log10 CFU/cm2 for T1, T2 and T3, respectively, and the faecal coliform counts were 0.09 log10 CFU/cm2 for T1, 0.06 log10 CFU/cm2 for T2 and 0.07 log10 CFU/cm2 for T3. No significant effects (P>0.05) were observed for carcasses physical characteristics of microbial growth, initial and ultimate pH and temperature, colour values and water holding capacity. It can therefore be concluded that organic Se-enriched yeast did not affect carcasses bacterial proliferation or meat physical characteristics.The authors wish to acknowledge the financial support to Mexican National Council for Science and Technology (CONACYT) Key Project 00000000011623