Chitosan films are an excellent media for binding metal ions due to the electrostatic nature of the chitosan molecules. Addition of cross-linking or plasticizing agents alters texture of the films, but their effect on metal-binding capacity has not been fully characterized. The objective of this research was to determine effects of plasticizers and cross-linkers on physical and metal-binding properties of chitosan films and coatings prepared by casting and by spincoating. Chitosan films were prepared using 1% w/w chitosan in 1% acetic acid with or without (control) additives. Plasticizing agents were tetraethylene glycol (TEG) and glycerol while citric acid, ethylenediamine tetraacetic acid (EDTA), and tetraethylene glycol diacrylate (TEGDA) were used as cross-linkers. The additives were applied in concentrations of 0.10%, 0.25%, and 0.50% w/w of film-forming solution. The films were prepared by casting and by spincoating. Films were cast at ambient conditions for tests within one week (fresh films) and eight weeks (aged) after casting. The cast films were evaluated for thickness, residual moisture (by the Karl Fischer method), Cr(VI) binding capacity, puncture strength, and puncture deformation while the chitosan coatings were tested for thickness, Cr(VI) binding capacity, solubility in aqueous solution, and surface morphology (using atomic force microscopy). Cast films with cross-linkers showed an increase in resistance to puncture while plasticized films become more elastomeric. Control films bound 97.2% Cr(VI) ions from solution (0.56 mg Cr(VI)/g film), and addition of plasticizers did not affect chromium binding, tying up to 96.7% Cr(VI) ions from solution (0.56 mg Cr(VI)/g film). Films containing cross-linkers yielded binding capabilities ranging from 42.3% to 94.3% bound Cr(VI) ions (0.26-0.52 mg Cr(VI)/g film). Ultrathin coatings also possess the ability to bind Cr(VI) from solution, though only a maximum of 7.4% of Cr(VI) ions could be bound from solution, the thin films had the ability to bind up to 224 mg Cr(VI)/g ultrathin film. These coatings use less chitosan, but they display greater binding per mass. Overall, plasticizers do not alter, while cross-linkers may reduce, the binding capacity of chitosan films, but physical properties of the films can be controlled by inclusion of additives.

Consumers’ demands for ω-3 polyunsaturated fatty acids (PUFAs) are at all-time high. Algae, a common source of PUFAs, and antioxidants are both used as supplements in livestock feeds, are known to affect the overall quality of meat. To implement PUFA deposits into broiler meat, this study evaluated combining antioxidants and algae in broiler feed to enhance the breast meat quality. Broilers were fed diets supplemented with 50 IU Vitamin E or 200 g/ton EconomasE (EcoE, an antioxidant pack) plus 10 IU Vitamin E, with or without 0.5% algae extract (SP-1). The feed oil was partially oxidized soybean oil (POV: 86 mEq of O2/kg). The feed supplementation with combined SP-1 and EcoE increased meat lipid oxidation but had no effect on protein. This combination supplement substantially reduced (P < 0.05) meat exudation during refrigerated storage while no evident differences were seen on cooking loss or tenderness between diets. Meat from SP-1 supplemented diets was found less acceptable than meat from other diets due to detected off-flavors. The results indicate that EcoE at a supplementation level other than 200 g/ton may be required to overcome off-flavors of broiler meat due to feed incorporation of 0.5% SP-1 with oxidized oil.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Neste trabalho são combinadas as potencialidades das técnicas quimiométricas e espectroscópica (NIR - infravermelho próximo) visando à determinação dos teores de proteína, óleo e umidade em grãos de sojas cultivadas no campo experimental da Embrapa Roraima, para os quais utilizou-se como referência o método Kjeldahl, o método de extração por Soxhlet e o método da estufa, respectivamente. Na construção dos modelos de calibração NIR estudou-se vários tipos de pré-processamento dos dados espectrais, faixas espectrais e conjuntos de amostras. O método de regressão usado na construção dos modelos foi o PLS (mínimos quadrados parciais) utilizando dados centrados na média para um conjunto de 90 espectros (calibração e validação interna). A avaliação dos modelos foi feita observando os valores de coeficiente de correlação (R) e os erros quadrados médios. Sendo os valores de previsão estimados para os demais 45 espectros não empregados na calibração. Para a determinação do teor de proteína, o melhor resultado foi obtido empregando correção multiplicativa de sinal (MSC) na faixa 1510-1980 nm, tendo RMSEP igual a 0,66. Para a determinação do teor de óleo o melhor resultado foi obtido empregando MSC com correção de linha base (BL) na faixa 1010-2500 nm, com RMSEP de 0,40. E para a determinação do teor de umidade, o melhor modelo foi obtido empregando a Transformação Padrão Normal de Variação (SNV) com correção de linha base (BL) na região de combinação das faixas 1870-2020 nm e 1400-1500 nm, que forneceu RMSEP de 0,12. Os erros relativos médios entre os valores previstos e medidos foram inferiores a 2 %. Com estes resultados concluiu-se que podem ser obtidos bons modelos visando à previsão dos teores de proteína, óleo e umidade em grãos de sojas cultivadas em Roraima, e que a técnica espectroscópica NIR aliada à regressão por PLS é adequada por permitir além de determinações rápidas e precisas, a não destruição das amostras nem a utilização de reagentes e por não gerar resíduos que sejam nocivos ao ambiente / In this study the potentialities of (NIR Near Infrared) spectroscopy and chemometrics techniques are combined aiming to determination of protein, oil and moisture in whole-grain soybean cultivated in the experimental field of the Roraima Embrapa, for which it was used as reference the Kjeldahl method, the extraction method by Soxhlet and the oven method, respectively. In the development of the models were studied several pre-processing types of the spectra data, spectral range and sample set. The regression method used in the development of the models was PLS (Partial Least Square) using mean-centered data, for a set of 90 spectra (calibration and cross validation). The evaluation of the models was made observing the values of correlation coefficient (R) and the root mean square error. The prevision values were estimated for the other 45 spectra nor used in the calibration set. For the determination of protein level, best results were obtained using Multiplicative Signal Correction (MSC) in the 1510-1980 nm range, obtaining RMSEP with values 0.66. For the determination of oil level, best results were obtained using MSC with transform Base Line (BL) in the 1110-2500 nm range, obtaining RMSEP with values 0.40. And for the determination of moisture level, best results were obtained using Standard Normal Variate Transformation (SNV) with BL, in the 1870-2020 nm and 1400-1500 nm combined range, obtaining RMSEP with values 0.12. The medium relative errors among predicted values and the measured values were inferior to 2%. With these results conclude that good models aiming the prediction of protein, oil and moisture levels in the whole-grain soybean from Roraima can be obtained. And that the technique NIR allied to the PLS regression is adequate to allow besides fast and precise determinations, the not destruction of the samples nor the use of reagents use and for not create wastes which are harmful to the environment

Three systems were compared in the first case study: (1). pre-dissolved β-carotene nanoemulsion (d< 200nm); (2). corn oil emulsion (d< 200nm) with β-carotene crystals being added before digestion; (3). phosphate buffer saline with β-carotene being added before digestion. Oil-in-water nanoemulsions were formed by high-pressure homogenization using Tween 20 as emulsifier and corn oil as carrier oil and then they were subjected to a simulated mouth, stomach and small intestine digestion. The rate and extent of free fatty acid production in small intestine decreased in the order (2)>(1)>(3); whereas the β-carotene bioaccessibility decreased in the order (1)>>(2)>(3). In system (3), even without any fat content, there is still noticeable consumption of NaOH, which is due to the ester bonds existing in the non-ionic surfactant (Tween 20). In the second case study, we developed two comparing groups by differentiating their oil concentration (20%, 4% respectively). The bioaccessibility of the high fat group is only half of the low fat group due to the insufficient digestion of fat in the former group. In the third case study, the bioaccessibility of nobiletin with different physical states (crystalized vs solubilized) and in different delivery system (conventional emulsion vs nanoemulsion) was compared. Not like β-carotene, the bioaccessibility of nobiletin as crystals in slightly lower than it is as solubilized state. Meanwhile, in conventional emulsion, the bioaccessibility is slightly lower than in nanoemulsion. This study provides important information for developing effective delivery systems for lipophilic bioactive components in food and beverage applications.

Owing to their increasing application and potential toxicity, engineered nanoparticles (ENPs) have been considered as a potential agricultural contaminant that may pose unknown risk to human beings. However, many techniques require invasive and complicated sample preparation procedures to detect and characterize engineered nanomaterials in complex matrices. In the first part of this thesis, we present a non-destructive and label-free approach based on surface enhanced Raman spectroscopic (SERS) mapping technique to qualitatively detect and characterize gold nanoparticles (AuNPs), on and in spinach leaves in situ. We were able to detect the clearly enhanced signals from AuNPs at 15 to 125 nm on and in spinach leaves. Peak characterizations revealed the aggregation status of Au NPs and their interactions with plant biomolecules, such as chlorophylls and carotenoids. This developed approach will open a new analytical platform for various researches on studying ENPs' adhesion and accumulation. The second part focuses on investigating the interaction between AgNPs and plant leaves using surface enhanced Raman spectroscopy. AgNPs of different surface coating (citrate, CIT and polyvinylpyrrolidone, PVP) and size (40 and 100 nm), were deposited onto spinach leaves. SERS signals produced from all kinds of AgNPs exhibited a unique C-S stretching peak at 650-680 cm-1. In vitro study indicates this peak may originate from the interaction between AgNPs and cysteine-like compounds based on the peak pattern recognition. The interaction between AgNPs and the cysteine-like compounds happened as soon as 0.5 h after AgNPs exposure. The in situ replacement of the CIT with the cysteine-like compounds on the AgNP surfaces was faster compared to that of the PVP. Based on the mapping of the highest C-S peak, we observed the CIT-AgNPs penetrated faster in spinach leaves than the PVP-AgNPs, although the penetration profile for both of them is similar after 48 h (P ˂ 0.05). The 40 nm CIT-AgNPs was able to penetrate deeper (to the depth of 183 ± 38 µm) than the 100 nm CIT-AgNPs (to the depth of 90 ± 51 µm) after 48 h. The results obtained here demonstrate the size of AgNPs is the main factor that affects the penetration depth, and the surface coating mainly affects the initial speed of interaction and penetration. This study helps us to better understand the distribution and biotransformation of AgNPs in plants. In the third part, the removal efficiency of postharvest washing on AgNPs that had accumulated on fresh produce was evaluated. Ten µL commercially available 40 nm citrate coated AgNPs (0.4 mg L-1) were dropped to a (1×1 cm2) spot on spinach leaves, followed by washing with deionized water (DI water), Tsunami® 100 (80 mg L-1) or Clorox® bleach (200 mg L-1). Then, AgNPs removal efficiency of the three treatments was evaluated by surface enhanced Raman spectroscopy (SERS), scanning electron microscopy (SEM)-energy dispersive spectrometer (EDS), and inductively coupled plasma mass spectrometry (ICP-MS). ICP-MS results showed that deionized water removed statistically insignificant amounts of total Ag, whereas Tsunami® 100 and Clorox® bleach yielded 21% and 10% decreases in total Ag, respectively (P < 0.05). The increased removal efficiency resulted from Ag NPs dissolution and Ag+ release upon contact with the oxidizing agents in Tsunami® 100 (peroxyacetic acid, hydrogen peroxide) and Clorox® bleach (sodium hypochlorite). According to the SERS results, the deionized water and Tsunami® 100 treatments removed nonsignificant amounts of AgNPs. Clorox® bleach decreased Ag NPs by more than 90% (P < 0.05), however, SEM-EDS images revealed the formation of large silver chloride (AgCl) crystals (162 ± 51 nm) on the leaf, which explained low total Ag removal from ICP-MS. This study indicates current factory washing methods for fresh produce may not be effective in reducing AgNPs (by water and Tsunami® 100) and total Ag (by all three means). This highlights the necessity to develop an efficient washing method for NP removal from food surfaces in the future.

Surface-enhanced Raman spectroscopy (SERS) is an emerging and sensitive technique in food analysis providing advantages of rapid detection, simple sample preparation and on-site detection capability over GC and LC methods. Most SERS applications focus on detecting trace amount of analyte in liquid as an alternative approach to HPLC. Herein, we invented an innovative SERS-active needle which is composed with an injection needle and a gold-nanoparticles coated fiber inside the injection needle. The gold nanoparticles-coated fiber was fabricated by reducing gold (III) on a chemically etched stainless wire. The SERS needle can be used to insert into the headspace and liquid sample for simultaneous multiphase sample detection, or a soft tissue like a tomato fruit to detect the analyte inside of the tissue with minimum invasion. Using this needle, we can detect as low as 5 ppb of fonofos in the headspace of water and apple juice samples, compared with the dip method, which cannot detect lower than 10 ppb in water and 50 ppb in apple juice. The SERS needle was also applied in real time pesticide translocation study to monitor internalized thiabendazole in tomato fruit after root uptake. The SERS needle detected thiabendazole inside tomato fruits 30 days after the pesticide exposure in a hydroponic planting environment. Moreover, realizing the advantage of detecting volatile components in the headspace of food sample, we applied the SERS needle in a ground beef spoilage study to detect the spoilage biomarkers in the headspace of the raw beef. As a result, the SERS needle detected volatile spoilage compounds produced by bacteria Lactobacillus. Overall, this invention opens a new field of SERS strategy for broad analytical applications.

Phospholipids can regenerate oxidized tocopherols and help delay lipid oxidation. The impact of emulsifier type, tocopherol homologue and phospholipid head group on tocopherol-phospholipid interaction was investigated in this study. Three µmol tocopherol/kg emulsion and 15.0µmol/kg emulsion of PE or PS were dissolved in oil and emulsions were prepared. Tween 20 or bovine serum albumin(BSA) was used as emulsifier and the continuous phase contained 10mM imidazole/acetate buffer at pH 7. Lipid hydroperoxides and hexanal were measured as lipid oxidation products and the lag phase was determined. With Tween 20 as the emulsifier, α and δ-tocopherol had a hexanal lag phase of 2 and 4 days respectively. PE and PS both extended the lag phase to 7 and 10 days respectively in presence of δ-tocopherol. Whereas, PS extended the lag phase to 6 days and PE could not exhibit any synergism with α-tocopherol. With BSA as the emulsifier, α and δ-tocopherol had a lag phase of 4 days. PE and PS extended the lag phase to 11 days and 10 days respectively in presence of δ-tocopherol and to 7 and 8 days respectively in presence of α-tocopherol. PE and PS both exhibited synergism with mixed tocopherol and the extent of synergism was in less than δ-tocopherol but more than α-tocopherol. Phospholipids could potentially be used with tocopherols to improve the oxidative stability of emulsions. PE was more effective with BSA whereas PS was equally effective with both emulsifiers.

Lipid oxidation is one of the major challenges faced by the food industry as it contributes to the loss of nutritional quality and loss of flavor in food products. Studies have shown that naturally occurring phospholipids like phosphatidylserine (PS) and phosphatidylethanolamine (PE) can regenerate oxidized tocopherols and help delay the lipid oxidation in bulk oils and oil-in-water emulsions. Since consumers desire simpler and cleaner labels, without chemically synthesized antioxidants, this research is of great interest. The combination of PS and PE with tocopherols has already been studied. However, PS was a better antioxidant in combination with tocopherols in the oil-in-water emulsion system whereas PE was a better antioxidant in combination with tocopherols in bulk oils. But obtaining pure phospholipids is an expensive deal, therefore, this study uses the more economical alternative, high phosphatidylserine (PS) lecithin in combination with mixed tocopherols in soybean oil-in-water system. PS (30 µmol/kg emulsion) along with mixed tocopherols (3 µmol/kg emulsion) were dissolved in oil and emulsions stabilized by Tween20 were prepared. To determine the most effective concentration of mixed tocopherols, 0.5, 1.0, and 3 µmole of tocopherols/kg emulsion were used at pH of 3 and 7. Tocopherol with a concentration of 3 µmole/kg emulsion was found to be the most effective at pH 3. Tocopherols showed an extended lag phase at lower pH. The synergistic activities of authentic PS and high PS lecithin were compared in combination with tocopherol under similar conditions. They both had an almost similar lag phase. This combination was then tested for different pH of 3 and 7 and different salt concentrations of (0.5, 1, and 1.5 wt% of the emulsion) at pH 7 to determine the effects of external factors on the synergistic antioxidant combination. It was observed that the combination had extended antioxidant ability at lower pH of 3 whereas salt had no effect on the combination. The results showed that high PS lecithin forms a synergistic combination with mixed tocopherols to increase the lag phase in oil-in-water emulsions and can be used as a clean label antioxidant for oil-in-water emulsions.

There has been a notable rise in the alternative protein market in the recent years which promotes an interest in the research of both animal and plant proteins to establish better structure-function relationships. Over the years many analytical tools have been used to study proteins and compare them, however Raman Spectroscopy and Surface Enhanced Raman Spectroscopy (SERS) have not been as much used for this application. SERS consolidates Raman Spectroscopy that primarily measures molecular vibrations and nanostructures that enhance the weak Raman signals. The objective of this study is to explore the capability of the Raman instrumentation in combination with different substrates for spectroscopic analysis of 3 animal proteins viz. whey, k-casein and albumin from chicken egg white and 4 plant proteins namely mung bean, soy, pea and faba bean. Herein, we firstly established a method that could be applied to all proteins to detect characteristic peaks that are related to their structure. Of all the methods, SERS with silver dendrites was the most promising method that detected protein characteristic peaks, particularly the shifts around 700-900 cm-1 attributed to the CN stretch and tryptophan groups. Although different proteins exhibit similar spectral characteristics, they were discriminated using principal component analysis. Then we explored the optimal method to study the effect of different environmental conditions including pH and salt concentration on the protein spectroscopic analysis. The limitations of the substrates were better understood during this process as Ag dendrites failed to provide a spectrum in the high pH range but was compatible with different salt concentrations. The peaks in the Amide-I region were vi used as a marker to study the effect of change in pH and salt. Most proteins showing a shift in the band suggesting a transition from α-sheet to a random coil conformation. The acquired spectra and subsequent PCA results depicted that pea protein was the most susceptible to change in pH amongst other proteins whereas faba bean was susceptible to a change in salt concentration. Finally, these learnings were applied to analyze a real-world food product to compare its spectroscopic characteristic with the standards we have. In conclusion, we demonstrated that Raman Spectroscopy and SERS was able to provide distinct spectroscopic characteristics of plant and animal proteins that may be used to facilitate the quality control or product development of novel plant-based food products. Future work will investigate the relationship between the spectroscopic characteristics and the structural function of proteins.

Sporadic problems with pink color defect, or pinking, has occurred in cooked meat products for decades. Pink color can be due to the presence of undenatured myoglobin, denatured globin hemochromes, or nitrosylhemochrome. This research documented the level of added nitrite that produced nitrosylhemochrome in processed meat rolls from fabricated beef round, pork shoulder, turkey breast, and chicken breast. For each meat type, preliminary studies were conducted to narrow the range at which added nitrite caused pinking. Subsequently, the nitrite levels were increased incrementally by 1-ppm, and pink color was measured by trained panelists and by a Hunter color meter. Nitrosylhemochrome content was determined by acetone extraction. Panel and instrumental measurements identified pink color in beef samples formulated with 14-ppm nitrite; nitrosohemochrome extracts detected pigment at 12- ppm. Nitrite levels that caused pinking in pork shoulder were much lower than in beef. Panelists identified pink color at 4-ppm nitrite, and Hunter color meter values showed increased redness at 6-ppm. Pigment extraction detected nitrosylhemochrome at 4- ppm added nitrite. The trained panel and Hunter color meter detected pink color in turkey breast at 2-ppm added nitrite; nitrosohemochrome extraction detected pink pigment at 3-ppm added nitrite. In chicken breast, pink color was detected visually and instrumentally at 1-ppm added nitrite. Pigment extraction detected nitrosylhemochrome at 2-ppm added nitrite. Lower levels of nitrite (1-3-ppm) caused pinking in light-colored meats (turkey and chicken breast, meats with total pigment between 19-ppm and 27-ppm). Higher levels of nitrite (5-14-ppm) caused pink color defect in dark pigmented meat (beef round and pork shoulder, meats with total pigment levels between 56-ppm and 147-ppm). Regression analysis was used to relate total pigment and the minimum level of nitrite causing pinking. The minimum nitrite level causing pinking was the lowest level of nitrite at which the trained panel, acetone extraction, and instrumental results detected pink color or nitrosyl pigment. The formula obtained from the model was as follows: Y = 0.092X + 0.53, where "Y" is the minimum level of added nitrite to cause pinking and "X" is the total pigment of the meat. This formula can be used to estimate the level of nitrite that can be expected to cause pinking in a wide range of pigmented meats.