Adriana Maria Descalzo

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.

LAB growth in semisolid fermentation substrates. Assays in quinoa with orange, mango and kefir. Analysis of protein, fat, lactic acid, vitamins, antioxidants and sterols. Effect of processing steps on macro and micronutrients in quinoa beverages.

Pecans are the nut with the higher oil content. In addition, they present a large number of polyunsaturated fatty acids, which are susceptible to oxidation. Oxidative damage in pecans is traduced in lower quality aspects, appearance of rancidity and acidity, loss of sweetness and firmness, darker kernels, and darker shells. The use of different strategies for the conservation of entire and shelled nuts is discussed in terms of oxidation and the consequences on nuts quality.

The aim of this study was to assess the efficacy of lactic acid (LA), caprylic acid (CA), high- (HDI) and low- (LDI) dose gamma irradiation and LDI combined with LA or CA on the inactivation of a pool of Shiga toxin-producing Escherichia coli (STEC) strains inoculated on beef trimmings. The three most efficacious treatments were selected to study their effect on meat quality parameters and sensory attributes. The inoculum included five native STEC serogroups (O26, O103, O111, O145 and O157). The treatments applied were 0.5% LA, 0.04% CA, 0.5 kGy LDI, 2 kGy HDI, LDI+LA and LDI+CA. Beef trimmings were divided into two groups; one was inoculated with high (7 log CFU/g) and the other with low (1 log CFU/g) level of inoculum. Efficacy was assessed by estimating log reduction and reduction of stx- and eae-positive samples after enrichment, respectively. Results showed that treatments with organic acids alone were not effective in reducing STEC populations. For high inoculum samples, the most effective treatment was HDI followed by LDI+LA and LDI alone or combined with CA. For low inoculum samples, the most effective treatment was HDI followed by LDI alone or combined with organic acids. Concerning meat quality parameters and sensory attributes, irradiation treatments (LDI and HDI) caused minimal changes, while LDI+LA modified them significantly compared with the control. Therefore, based on our results, no benefits were observed after combining organic acids with gamma irradiation.

A 120-d feeding trial was conducted to determine the effect of alfalfa (Medicago sativa) feeding on growth and chemical composition, fatty acid content, and nutritional and lipid indices of the meat of grass carp (Ctenopharyngodon idella). Two experimental diets were used: alfalfa pellet (AP) diet and artificial grain diet (GD). Final weight, feed conversion rate, and protein efficiency ratio were significantly greater in the GD group (P < 0.05). However, no differences in the length and condition factor were observed. The composition of the meat differed between treatments. The protein content was significantly greater in the AP group (P < 0.05), while the lipid and cholesterol contents were significantly greater in the GD group (P < 0.05). A greater proportion of saturated, n-6 polyunsaturated, and n-6 highly unsaturated fatty acids was obtained in the GD group. The AP group accumulated a greater concentration of eicosapentaenoic (EPA), docosapentaenoic (DPA), and docosahexaenoic (DHA) acids (P < 0.05). The fatty acid composition of the meat determined a significant decrease in the thrombogenicity index and saturation index (S/P) in the AP group (P < 0.05). The Elongase index was greater in the GD group (P < 0.05). In contrast, the AP group had a greater index of Δ9 Desaturase and Δ5 + Δ6 Desaturase for n-3 and n-6 fatty acids (P < 0.05). These results suggest that alfalfa feeding decreases the growth of C. idella but improves the quality of meat by increasing the protein, EPA, and DHA contents. It also reduces cholesterol content and improves nutritional indices.

Droëwors are traditional South African salted and dried sausages, made without nitrites/nitrates and non- fermented. Different meat sources (beef, game and ostrich) are traditionally used in droëwors processing, while the use of pork is uncommon, as it is said to lead to rancidity. The first part of the study analysed the physico-chemical composition of commercially available beef, game and ostrich meat droëwors (n = 20). On average, they were composed of 26.3–29.2 g/100 g moisture, 41.3–44.0 g/100 g protein, 26.2–33.1 g/100 g fat and 5.9–6.5 g/100 g ash and 5.0–5.4 pH. Water activity (0.76–0.82) was sufficiently low to ensure shelf stability at ambient temperatures. In the second part beef and pork droëwors were formulated in accordance with these results and with similar fat content, dried for 2 days (30 °C, 40% relative humidity) and stored for 26 days (25 °C, 50% relative humidity); measuring moisture, water activity, pH and lipid oxidative stability (thiobarbituric acid reactive substances (TBARS)) weekly. At day 5, moisture and thus water activity of pork droëwors was slightly higher compared to beef ones and fat and ash content slightly lower (P ≤ 0.05) despite similar weight loss. Even with slightly less fat, TBARS in pork droëwors were significantly higher after drying and throughout storage (3.83 vs 0.99 mg MDA equivalents/kg dry matter at a maximum).