Gabriela Grigioni

The study determined the optimal conditions for extracting antioxidant phenols from Mutisia friesiana (Asteraceae) using ultrasound-assisted extraction. We evaluated extraction time, ethanol concentration, and solid/solvent ratio, applying a Box-Behnken experimental design. Response variables were total phenolic content (TPC), DPPH free radical scavenging activity (EC50), and ferric reducing antioxidant power (FRAP). All extraction variables were optimized by the response surface methodology. The optimal conditions resulted in 15 minutes of extraction, 65% ethanol, and a solid/solvent ratio of 5 g/100 mL. Under these conditions, TPC, EC50, and FRAP values were 54.24 mg GAE/g dw, 31.40 µg/mL, and 965.32 µmol EFe(II)/g dw, respectively. Extract HPLC–MS analysis under optimal conditions identified four phenolic compounds, previously reported for their antioxidant properties. This study provides valuable insights into optimal extraction parameters of bioactive compounds from M. friesiana, positioning the species as a promising natural antioxidants source for the food industry, particularly meat products. Highlights: Ultrasound-assisted extraction (UAE) was optimized to recover antioxidant phenols from Mutisia friesiana using response surface methodology. Optimal conditions yielded an extract with high antioxidant activity. HPLC-MS identified four antioxidant phenols in the optimized extract.

Pecans are a source of protein, fiber, bioactive compounds, and are rich in fatty acids. Their quality depends on postharvest and storage (temperature, light, and relative humidity). Pawnee nuts were dried at 30 °C up to 4% moisture content. In-shell pecans were stored in raffia bags at 20 °C in darkness for two and four months (2M/4M). They were then shelled and vacuum-sealed for 0, 4, 8, and 12 months in darkness, before being exposed to light and ambient light for 0, 20, and 40 days. The attributes evaluated were water activity, moisture (%), peroxidation (meq O2/kg oil), TBARS (meq MDA/kg nut), luminosity, and instrumental hardness (N). Results were analysed using Dunn's test with a 5% significance level. For 2M, day 0 peroxidation values increased slightly up to eight months of vacuum and darkness, below 2 meq O2/kg oil. Changes in texture in the fourth and eighth months were related to water activity, and higher peroxide and TBARS values for days 0 and 20, decreasing lightness. At 4M, alterations in water activity, moisture, lightness, and texture, along with higher peroxide and TBARS values, were observed in the fourth and eighth months. Compared to 2M (p<0.05), this resulted in a significant decrease in quality. These findings suggest the potential for preserving pecan nuts under 2M conditions, vacuum and darkness for a maximum of eight months, with subsequent immediate sale of shelled nuts.

The objective was to evaluate the performance and meat quality of Holando Argentino (HA) steers under different feeding strategies. One hundred twenty-eight HA steers (181.4 ± 25.5 kg of live weight [LW]) were allocated to four treatments: FL: feedlot finishing during 98 days; Gr1.25: grazing with 1.25% LW/day maize grain supplementation during 235 days; Gr0.70: grazing with 0.70% LW/day maize grain supplementation during 331 days; and GrFL: 287 days grazing background and 116 days feedlot finishing. Average daily gains (ADG) were 1.14, 1.02, 0.82, and 0.81 kg/day for FL, Gr1.25, Gr0.70, and GrFL, respectively (p0.05). GrFL and Gr0.70 presented the highest carcass weight (CW; 288.3 ± 5.0 and 267.8 ± 12.2 kg, respectively, p<0.001). Gr0.70 presented the lowest longissimus thoracis (LT) L* (p<0.01) and the highest a* (p<0.05). Intramuscular fat was the highest for GrFL (4.86 ± 0.93%, p<0.05). In all strategies, LT shear force presented values of tender meat (29.9 ± 3.4 N, p=0.60). HA steers have the flexibility to produce tender meat under different, high-productivity strategies. Highlights: Holando Argentino steers produced tender meat under contrasting feeding strategies with high productivity. Intramuscular fat content was mainly determined by total grain intake. Grains can be used at different phases to manage live weight gains, as well as subcutaneous and intramuscular fat endpoints. Average daily gains, fat thickness, and carcass weight influenced meat color.

Zymography stands as a versatile technique pivotal in elucidating the effects of hydrolases on diverse biological substrates. The casein zymographic assay has emerged as a gold standard for assessing calpain activity, particularly in mammalian systems. This method allows for the simultaneous monitoring of calpain isoforms and calpastatin, the endogenous inhibitor, without the need for prior enzyme purification. Employing non-denaturing conditions on acrylamide gels embedded with casein, this protocol facilitates the digestion of casein by active calpains, resulting in distinct zones of proteolysis upon Coomassie blue staining. The differential gel mobility of calpain isoforms further aids in their differentiation. This methodology has been essential in investigating the impact of various factors, such as feeding strategies and postmortem treatments, on calpain activity in meat from different animal sources. This chapter focuses on the application of casein zymography and highlights the utility of this protocol in detecting calpastatin activity, overcoming previous limitations in its assessment.

Research background. A few studies have investigated Cynara scolymus enzymes as a substitute for calf rennet in cheese making. They used aqueous extracts prepared by maceration of plant material and stored by freezing. However, it was indicated that lyophilisation is a better alternative to preserve the coagulant properties of plant extracts over a longer period of time, as it is a more controllable, stable and hygienic alternative with a better shelf life that is easier to transport, store and standardise. Experimental approach. We obtained a lyophilised extract of mature artichoke flowers, named CS, which was characterised for its milk-clotting properties at different pH and temperatures. In addition, the potential yield, whey composition and the primary hydrolysis profile of caseins by urea-polyacrylamide gel electrophoresis (PAGE) of mini curds prepared with different doses of coagulant were determined. Results and conclusions. The lyophilised extract was able to hydrolyse casein and showed stable proteolytic activity at pH=6.4 and 37 °C for 50 min, which decreased when the process temperature was increased to 41 and 45 °C and was lost at 70 °C. On the other hand, milk-clotting activity increased significantly (p<0.001) when the temperature increased from 37 to 45 °C and the pH of the milk decreased from 6.8 to 5.8. Potential yield between 10 and 17 % was obtained for the mini curds prepared with the lyophilised artichoke extract, and the casein degradation pattern obtained by urea-PAGE was similar to that of the commercial coagulant. Novelty and scientific contribution. On a laboratory scale, our work has shown that the lyophilised artichoke extract has sufficient proteolytic and coagulant activity to be used as a milk coagulant, i.e. plant rennet, in cheese making as an alternative to animal rennet. As this extract is lyophilised, it has the advantage of being a better alternative in terms of preservation and shelf-life. It offers an innovative way to diversify cheese products and appeal to consumers with different dietary preferences and needs.

Distiller grains (DG), which are the by-product from the bioethanol industry, represent an interesting alternative as animal feedstock. To our knowledge, little information is available on the inclusion of DG on the quality of meat from pasture-fed heifers. Thus, the aim of the present study was to evaluate the effect of DG inclusion in pasture-based systems on the main meat quality attributes of Charolais x Aberdeen Angus heifers. For this purpose, meat from heifers fed with a pasture-based diet without supplementation (P) or with 0.75% of live weight DG supplementation (PDG; DG plus dry-rolled corn, 50:50) or with 0.75% of live weight dry-rolled corn supplementation (PRC) was evaluated. Physical (pH, WHC, color, texture), sensory and nutritional (fat content, fatty acid, and amino acid profile) attributes were evaluated in beef samples. No effect of supplementation was observed on meat pH or color (p > 0.05). Meat from PDG heifers showed higher values of WBSF than meat from P heifers (p = 0.039). However, the overall tenderness evaluated by trained panelists showed no differences due to supplementation (p > 0.05). Our results indicate that the inclusion of DG as a partial corn-replacement supplementation for heifers under grazing represents a strategic tool not only related to meat quality, but also as an alternative to reduce food–feed competition.

Objective: This study was conducted to evaluate Raman spectroscopy technique as a noninvasive tool to predict meat quality traits on Braford longissimus thoracis et lumborum muscle.Methods: Thirty samples of muscle from Braford steers were analyzed by classical meat quality techniques and by Raman spectroscopy with 785 nm laser excitation. Water holding capacity (WHC), intramuscular fat content (IMF), cooking loss (CL), and texture profile analysis recording hardness, cohesiveness, and chewiness were determined, along with fiber diameter and sarcomere length by scanning electron microscopy. Warner-Bratzler shear force (WBSF) analysis was used to differentiate tender and tough meat groups.Results: Higher values of cohesiveness and CL, together with lower values of WHC, IMF, and shorter sarcomere were obtained for tender meat samples than for the tougher ones. Raman spectra analysis allows tender and tough sample differentiation. The correlation between the quality attributes predicted by Raman and the physical measurements resulted in values of R2 = 0.69 for hardness and 0,58 for WBSF. Pearson's correlation coefficient of hardness (r = 0.84) and WBSF (r = 0.79) parameters with the phenylalanine Raman signal at 1,003 cm-1, suggests that the content of this amino acid could explain the differences between samples.Conclusion: Raman spectroscopy with 785 nm laser excitation is a suitable and accurate technique to identify beef with different quality attributes.

In the Argentine Puna Jujeña, agricultural producers have high-altitude livestock as their main activity. Traditionally, llamas are fed on natural pastures, being grain supplementation an alternative when there is low availability and quality of grass. The aim of this work was to evaluate the effect of two levels of grain supplementation on meat quality of llama (Lama glama) raised in natural pastures. Two fattening trials were carried out with eighteen intact male llamas in each one. In the first, a 1.5 % grain supplementation was used (S1.5 %) and in the second, a 2 % (S2 %), of the average live weight of the group on a dry basis. The group of animals that did not receive grain supplementation was considered as control treatment (T) and was assigned only direct grazing of the lots, which were made up of natural grasslands. The supplementation consisted of ground corn grain (80 %) and soybean expeller (20 %). It was offered in a daily group delivery, in the morning. An experimental design in randomized complete blocks was used. The first trial lasted 34 days, the second, 60 days, both with a previous 10-day adaptation period to the new diet. In both trials, no differences were observed in the meat sensory traits according to the feeding strategies. Grain supplementation modified meat texture, resulting in meat with increased toughness. Meat can be characterized as lean and with low atherogenic and thrombogenic potential. Based on the results, the proposed feeding strategy could improve the meat supply, preserving the cultural and territorial identity in the Puna Jujeña region.

In South America, modifications in beef consumption habits, mainly related to economic reasons, new lifestyles, and new eating behaviors, are being observed. If this trend continues, beef consumption could continue to fall or there would be a greater share of cheaper types of meat. In general, consumer concerns related to health, animal welfare, and environmental impact are increasing. Most of the population in South America follows an omnivorous diet, with a minority of vegetarians/vegans. In Argentina, around 30% consider themselves as flexitarians and around 5% as vegetarians/vegans, with centennials and millennials being the ones that mostly follow these types of behaviors. For flexitarians, the main reason that leads them to adopt this diet is the search for healthier eating. In general, consumers consider livestock production to be a sustainable activity; although, ethical concerns are growing among the younger generations. Finally, around 30% of the total population is willing to partially replace the consumption of beef to avoid animal slaughter and 8% would abandon it for this reason. The current trend would indicate that, if the conditions defined by the present scenarios continue, the motivations to consume less beef could be strengthened.

The aim of this work was to study the effect of finishing diets including distiller grains (DG) on color and oxidative stability of beef after being exposed to aerobic retail display conditions, with or without previous aging. For this purpose, beef samples from animals fed with finishing diets including 0%, 15%, 30%, and 45% DG (on a dry matter basis), which had been exposed to aerobic retail display conditions, with or without previous aging under vacuum packaging, were evaluated. The content of γ-tocopherol, β-carotene, and lutein in diet samples increased with the level of DG. Beef evaluated at 72 h post-mortem showed greater content of γ-tocopherol and retinol as the DG level increased. Meat color was not affected by DG inclusion, but color parameters decreased with retail conditions. Meat from animals fed with DG showed the lowest values of thiobarbituric acid reactive substances (TBARS), independently of the retail display conditions. However, all samples were below the threshold associated with rancid aromas and above the a* value related to meat color acceptance. Thus, feeding diets including up to 45% of DG improved the antioxidant status of meat, preserving the color, and delaying lipid oxidation in meat samples under the display conditions evaluated.