Ciencias Exactas y Ciencias de la Salud
Permanent URI for this collectionhttps://hdl.handle.net/11285/551014
Pertenecen a esta colección Tesis y Trabajos de grado de los Doctorados correspondientes a las Escuelas de Ingeniería y Ciencias así como a Medicina y Ciencias de la Salud.
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- Evaluation of compositional changes in pecan nuts during storage and the use of pulsed electric fields as an aid to enhance oil extraction yield(Instituto Tecnológico y de Estudios Superiores de Monterrey, 2021-02) Rábago Panduro, Lourdes Melisa; RABAGO PANDURO, LOURDES MELISA; 418204; Welti Chanes, Jorge; hermlugo, emipsanchez; Serna Saldívar, Sergio; Chuck Hernández, Cristina; Escuela de Ingeniería y Ciencias; Campus Monterrey; Morales de la Peña, MarianaPecan nut kernels have been identified as an important source of mono- and polyunsaturated fatty acids, phytosterols, tocopherols, and phenolic compounds. Likewise, the oil commonly extracted by mechanical pressing of pecan nut kernels, is considered a specialty product due to its phytochemical profile. However, the effect of processing and storage on these bioactive compounds and how to improve the mechanical extraction of pecan nut oil have been scarcely investigated. Pulsed electric fields (PEF) are being applied as a pretreatment to improve oil extraction from different seeds increasing the oil extraction yield (OEY) and enhancing the oil phytochemical profile. Therefore, this dissertation aimed to evaluate i) the effect of drying and storage conditions on phytochemical content and antioxidant capacity (AC) of pecan nuts, and ii) the application of PEF as a pecan nuts pretreatment to improve OEY along with its effect on oil stability and bioactive compounds concentration of the oil and by-product generated usually named cake. Fatty acids, tocopherols, phenolic compounds (PC), and AC of fresh and dry kernels were determined to assess the effect of drying on pecan nuts. PC and AC of kernels and in-shells nuts stored during 240 days at 4 and 25°C were analyzed to study the effect of storage conditions. PEF was evaluated on fresh and dry pecan nuts by comparison of PEF-treated kernels against untreated and soaked kernels. Fresh kernels were pretreated at different levels of specific energy inputs (0.5–17.6 kJ·kg-1) to evaluate OEYTOTAL, oil acidity and AC along with cake PC and AC. Dry kernels were pretreated at 0.8, 7.8, and 15.0 kJ·kg-1 to assess OEYTOTAL and kernels microstructure. Oil stability was investigated by determination of acidity, AC, oil stability index (OSI), phytosterols, tocopherols, and lipoxygenase (LOX) activity. Cake PC and AC were also analyzed. The results showed that the drying process reduced the initial concentration of PC and AC (33.2 and 22.3%, respectively), but it helped to preserve pecan nut kernels for 240 days without microbial deterioration. During storage, a decrement of condensed tannins (CT) concentration (31.5–41.8%) and an increment of AC (188.4–216.4%) on both kernels and in-shell nuts were observed. Regarding the evaluation of PEF, water immersion of fresh kernels to PEF pretreatment decreased the initial oil content (7.3–11.7%). Despite that, the highest OEYTOTAL was achieved in kernels pretreated at 0.5 kJ·kg-1, being 21.4 and 17.6% higher than values of untreated and soaked kernels, respectively. A rise of PC content was observed in cakes generated from kernels pretreated at 0.8 kJ·kg-1 in comparison with cakes from untreated and soaked kernels (9.5–17.8 and 30.1–39.3% for PC and CT, respectively). Despite PC improvement, the PEF pretreatment did not increase the AC of cakes. Dry kernels water immersion also caused a reduction of the initial oil content (9.7%). OEY of untreated kernels was 88.7%, being higher than OEYTOTAL of soaked (76.5–83.0) and PEF-treated kernels (79.8–85.0%). The microstructural analysis of kernels pretreated at 0.8 kJ·kg-1 showed that PEF processing induced oleosomes fusion within the intracellular space of kernels cotyledon tissue. Neither soaking nor PEF processing significantly modified oil acidity, AC, OSI, and LOX activity. In contrast, the application of 0.8 kJ·kg-1 to dry kernels increased cake CT and AC by 43.5 and 21.8%, respectively, compared to untreated kernels while in comparison with control kernels was 27.0 and 24.3% higher, respectively. This dissertation proved that PC and AC of kernels are highly susceptible to drying and storage time, evidencing their impact on the functional properties of pecan nuts. Concerning pretreatment with PEF, it was demonstrated that it is necessary to take into consideration the recovery of the oil retained into the soaking water. Furthermore, the effectiveness of PEF to improve OEYTOTAL depended on whether the pretreatment was applied to fresh or dry pecan nuts. The microstructural analysis showed that the application of PEF modifies kernels oleosomes. Oil extracted from PEF-treated kernels displayed comparable characteristics to pecan nut oil extracted by mechanical and solvent processes. The by-product generated from PEF-treated kernels exhibited an improved CT concentration, making it an attractive ingredient to consider in food formulations.
- Validation of a selenized chickpea flour as a potential ingredient for functional foods(Instituto Tecnológico y de Estudios Superiores de Monterrey, 2021) Serrano Sandoval, Sayra Nayely; Gutierrez Uribe, Janet Alejandra; dnbsrp; Serna Saldívar, Sergio Román Otón; School of Engineering and Sciences; Campus Monterrey; Guardado Félix, DanielaGermination of chickpea (Cicer arietinum L.) in presence of selenium (Se) is an alternative to increase the mineral and healthy-related properties of the sprouts. This study aimed to produce an Se-enriched chickpea sprouts flour as an ingredient for functional foods. Firstly, the Se-stored protein fraction was identified, and the protein hydrolysates cellular antioxidant activity (CAA) was evaluated. Secondly, the germination in presence of Se was scaled up to meet the criteria of saving and expanding production, obtaining high Se and isoflavones concentrations in the chickpea sprouts. In third place, the formulation and evaluation of a food containing germinated chickpea flour was carried out. Finally, the adjuvant capacity against colon cancer in xenografted mice model of a diet containing Se-enriched chickpea sprouts flour was evaluated. For the first step, chickpeas were germinated at laboratory conditions for 4 days soaking with sodium selenite (Na2SeO3) (0, 1, or 2 mg/100 g seeds). The protein fractions were digested, identified by Tricine-SDS-PAGE gels, passed through a 10kDa membrane, and evaluated by CAA. Se was accumulated in the order Glutelin (Glu) > Albumin (Alb) > Globulin (Glo). Glu hydrolysate of less than 10kDa from selenized chickpea sprouts (2 mg of Na2SeO3/100 g seeds) increased by 51.5% the CAA related to non-selenized chickpea sprouts. Besides, it was found that Glo digestibility increased with the selenization. For the second step, different doses of Na2SeO3 were used to soak the seeds (0, 24, 48, or 96 mg/L) at industrial level. Freeze- and convection-drying (FD, CD) were evaluated on the Se retention, isoflavones, and enzymatic activities (β-glucosidase, phenylalanine-ammonia-lyase, PAL). Increases of 65% and 19% were observed in PAL and phenolics, respectively when the lowest dose of Se was used. CD did not affect the Se content in the sprouts soaked with 0, 24, and 48 mg/L, and converted isoflavones glycosides into aglycones due to β-glucosidase activation. The highest dose of Na2SeO3 (96 mg/L) was found toxic. At the third objective, maize extrudates supplemented with germinated chickpea flour were formulated. Protein augmented with the chickpea supplementation and the interaction between fat, starch, and protein increased the RS in comparison to defatted samples. Germinated chickpea flour increased the water absorption index (WAI), but reduced water solubility index (WSI) when it was combined with maize grits to produce extrudates. The in vitro protein digestibility (IVPD) was higher in the germinates chickpea extrudates and with 20% of supplementation. The supplementation with 20 and 30% of germinated chickpea showed the highest acceptability. Finally, the tumor growing was evaluated with a Gompertz model and the lipid, liprotein and GPx and TrxR were evaluated. The Ti observed for NC group was significantly higher than the observed in the selenized C15Se and C30Se groups by 1.26-fold. HDL-C in serum showed that there were significant differences between the C30Se group and NC and C30 groups by 1.07- and 1.12-fold. C15NSe did not show inhibitory effect on the tumor growth and could be related to the observed in the LDL-C levels in contrast to observed in C60, C15Se, and C30Se. Triglycerides of basal group was significantly higher than those measured in C15, C30, C15NSe, and C30Se group; the reductions were in a range of 22 to 28% with the experimental groups. Almost an increase of 2-, 1.6-, and 1.9-fold were found in the GPx groups in selenized treatments in comparison to basal, NC, and C15 groups, respectively. As a result, C30Se showed the best significant outcomes in the in vivo study: lower Ti compared to NC, higher HDL-C compared to NC and C30; lower triglycerides compared to basal group; and higher GPx activity compared to basal, NC, C15, and C30 groups.