Anubhav Pratap-Singh

There has been a burgeoning interest in blueberry consumption due to its nutritional and health benefits. However, blueberries are very perishable due to their susceptibility to water loss and mould deterioration, affecting their quality and shelf-life. The objective of this study was to optimize innovative post-harvest strategies, pulsed light (PL) and controlled atmosphere storage (CAS) to improve the quality and shelf-life of highbush blueberries grown in BC. We hypothesized that the post-harvest shelf-life of highbush blueberries could be extended through using PL and CAS while both strategies meet the consumer demand for natural, and minimally processed foods. In this study, the effect of four CAS conditions (8kPa CO2 + 1.5kPa O2; 8kPa CO2 + 10kPa O2; 15kPa CO2 + 1.5kPa O2; 15kPa CO2 + 10kPa O2) and three PL treatments with doses of 3, 6, and 9 Jcm-2 were assessed using for their impact on the final quality and shelf-life of highbush blueberries (cv. Draper). In addition, the berry quality parameters (colour, firmness, weight loss, and rot incidence), antioxidant activity, pH, titratable acidity, and total soluble solids, and shelf-life were analyzed during six weeks. All CAS and PL treatments showed decreased weight loss compared to the regular atmosphere storage at the end of the storage. PL doses of 9 Jcm-2 showed less rot incidence, and PL doses of 6 Jcm-2 showed higher firmness compared to control; however, no significant difference (p 0.05) has been observed in PL treated blueberries in all CAS in terms of firmness and rot incidence compared to control by week six. Increasing PL doses decreased antioxidant activity during storage time. Total soluble solids (TSS) and total acidity (TA) increased with increasing PL doses in the lower O2 concentration storage. Results showed that treating blueberries with PL doses of 6 and 9 Jcm-2 in CAS of 10kPa O2 and 8kPa CO2 provided the optimal conditions for maintaining the blueberries’ quality traits after four weeks. These findings can help increase the quality and shelf-life of blueberries, while minimizing their environmental impact, which could significantly impact the industry market, locally and globally.

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The overconsumption of dietary fat contributes to chronic diseases such as obesity, diabetes 2, and cancer, (WHO, 2016). Thus, fat reduction has become one of the major concerns in the food industry and research communities. However, the fat content has a clear impact on food texture, hence fat reduction highly impacts acceptance by the consumer. Such impact can be bypassed by processing carbohydrates into microparticles for their use as a fat replacer. Whenever the particle size is maintained under the threshold of perception, important properties derived from the presence of fat are maintained. The present work demonstrates the application of the spray drying technique to produce microparticulates of dietary fibers, with particle sizes less than 10 µm and examines their role as fat replacers for hazelnut spread. Microparticles of inulin, konjac glucomannan, chia mucilage and psyllium husk were generated for their use as a fat replacer. The use of spray drying leads to high yields (83 %) and microparticles with a projected area equivalent diameter between 5 to 11 μm, a size range representing fat globules. Results demonstrated that spray-dried microparticles composed of dietary fibers were an optimal fat replacer for hazelnut spread creams. Optimization of a dietary fiber formulation containing these fibers, to obtain high viscosity, water holding capacity, and oil holding capacity was conducted. Microparticles containing 46.1, 46.2, and 7.6 weight percentage of chia mucilage, konjac glucomannan, and psyllium husk showed a spraying yield of 83.45%, solubility of 84.63%, and viscosity of 40.49 Pas. When applied to hazelnut spread creams, microparticles substituted palm oil by 100% and produced a product with total and saturated fat reduction of 41 and 77 %, respectively. An increase in dietary fibers of 4 % and a decrease in total calories of 80 % were also induced when compared with the original formulation. Hazelnut spread with dietary fiber microparticles was preferred by 73.13% of participants in the sensory study due to an enhancement in brightness. The demonstrated technique could be used to increase the fiber content while decreasing the fat content in some commercial products, such as peanut butter or chocolate spread.

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Sulfur dioxide (SO₂) is a widely used wine preservative that can protect the wine from oxidation and microbial spoilage. However, in the last two decades, the wine industry has been investigating possible alternatives to reduce or even replace it due to its adverse effects on sulfite-sensitive individuals. In this study, the possibility of using a continuous Pulsed Light (PL) system for the inactivation of spoilage microorganisms to reduce the use of SO₂ in red wine and its effects on anthocyanin condensation reaction was investigated. Model wine solutions containing malvidin, cyanidin, and delphinidin-3-O-glucoside were prepared with the presence of (-)-epicatechin and acetaldehyde. The solutions were subjected to PL treatment with 2, 4, and 8 J/cm² energy and stored at 10 °C. The loss of anthocyanin during the treatment and the aging period fitted the first-order reaction model. Delphinidin-3-O-glucoside suffered the highest loss, while malvidin-3-O-glucoside showed the lowest loss. Furthermore, the PL treatment significantly influenced the kinetics of anthocyanin loss during the aging period. PL treatment led to the formation of new isomers of anthocyanin ethyl-linked (-)-epicatechin in the treated samples that were not detected in the control samples. The color characteristics of the model solutions were affected by the PL treatment and the formation of ethyl-linked products.Red wine samples with 0, 25, and 50 mg/L free SO₂ were subjected to PL treatment with 0, 2, and 4 J/cm² fluences. Physicochemical properties and microbial count were monitored for four months. The results showed that PL treatment could significantly reduce the number of LAB and yeast. After the aging time, the samples with no SO₂ added showed a higher pH, lower acidity, TPC, and anthocyanins. In addition, the total color changes were low and could not be detected by human eyes. According to the findings in this study, the PL treatment could significantly inactivate wine spoilage microorganisms with no noticeable effects on the color. As a result, the use of SO₂ can be limited. However, to prevent the oxidation of anthocyanins and maintain the quality of wine, there is still a need to use a reduced amount of SO₂.

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Fortification of black tea with iron and zinc has the potential to reduce the prevalence of iron and zinc deficiency in the developing world. Tea is an ideal vehicle for food fortification because it is the second most consumed beverage globally, aside from water, and is consumed throughout the world independent of socioeconomic strata. Unfortunately, polyphenolic compounds present in tea form complexes with iron, which cause colour changes. The formation of this intensely blue-purple non-bioavailable iron-polyphenol complex is a barrier to consumer acceptance and the public health effectiveness of iron-fortified tea.The objective of this study was to develop and assess the fortification of tea with microencapsulated iron and zinc to increase their absorption, and that could prevent the formation of the iron-polyphenol complex in tea. Whey protein isolate and Eudraguard® that either provide gastric and intestinal protection and increase bioaccessibility of iron and zinc in the human body, were used as coating materials for the development of the microencapsulated iron and zinc. A response surface design was used to optimize the encapsulation efficiency of iron and zinc in the microcapsules. The microcapsules were subjected through a simulated gastric and intestinal digestion, whereas the microcapsules showed higher resistance to intestinal conditions.Absorption studies performed using a Caco-2 cell model revealed that the iron delivered through the microcapsules increased cellular absorption by 73%. Zinc from the microcapsules also increased cellular absorption by 81%. The iron-polyphenol complex is dependent on the pH, therefore, the use of MES and PIPES buffers was investigated for the measurement of the iron-polyphenol complex formation. The results show that MES buffer at 0.2M and pH 5.5 can be used to quantify the iron-polyphenol complex in a polyphenolic model system (gallic acid), closely resembling tea. The prevention of the iron-polyphenol complex formation was further investigated with the microencapsulated iron and zinc using a gallic acid and brewed tea. The microcapsules slowed down the formation of iron-polyphenol complex in tea by 60% within 30 minutes of tea brewing. The results of this thesis have the potential to guide the path to reduce micronutrient deficiencies, through fortification of commonly consumed tea with iron and zinc.

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Pea (Pisum sativum L.) has garnered recent attention as a plant-protein source due to its high protein content, nutrient density and low allergenicity. However, pea proteins are difficult to incorporate into food formulations due to undesirable green, grassy and beany aromas and limited functional properties. Direct steam injection is often used in the food industry to decrease off-flavour intensity of pea proteins and improve functional properties. However, induced cooked off-flavours and nutrient losses that are attributed to heating warrant exploration of an alternative process. This research examined the applicability of vacuum microwave dehydration as a pre-processing step for plant protein for use during non-dairy alternative production. In this thesis, effects of the following process parameters: initial moisture content (5-425% dry basis), vacuum level (40-200 Torr), specific power (10-200 W/g), and process time (1-50 minutes) on volatile compound concentration, functionality and quality parameters such as available lysine and colour, were analyzed. Increasing initial moisture content decreased (p0.05) protein solubility, emulsifying activity index and chemically available lysine content, but increased (p0.05) emulsifying stability index. Having a higher initial moisture content decreased (p0.05) lightness, but increased (p0.05) the a* and b* coordinates and total colour difference compared to untreated pea protein. Generation of specific volatiles related to thermally induced lipid oxidation was observed in some samples, thus, necessitating lower specific energy treatments to be considered.Results showed that three VMD processes could be developed for use on two sources of pea proteins. VMD-processing pea protein with an initial moisture content of 162% d.b. at 100W/g microwave energy and 200 Torr vacuum-level for 2.5 minutes was found to be the optimal conditions for retaining functional properties and minimizing volatile concentration that contributed to off-flavour intensity.Descriptive analysis showed that the finalized VMD-process reduced levels of “raw/beany” and “green/grassy” aroma and flavour, but increased overall aroma intensity, “goaty/caproic acid” aroma and “chalky flavour”. Future consumer trials are needed to verify whether these differences in attribute intensities are relevant at the consumer level.

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Pea is a nutritious legume that can be used as an animal protein substitute. However, the unpleasant greeny aroma severely inhibits the application of pea-derived proteins as a food ingredient. This study aims at improving the aroma of pea protein isolates (PPIs) with an aim to employ these PPIs for plant-based dairy substitute production. Major objective of this study is to establish the applicability of lactic acid fermentation (LAF) in eliminating unpleasant aroma from PPIs while maintaining the functional properties and protein quality. We hypothesize that LAF treatment can reduce the undesirable aroma of pea protein isolates by virtue of desirable bacterial action on plant proteins. A solid-phase microextraction followed by gas chromatography-mass spectrometry (SPME-GC-MS) method was developed in this study to identify and quantify the volatile compound profile of plant-based protein. Total concentration of volatile compounds belonging to aldehyde, ketone and alcohol group in the pea, soy and brown rice protein is analyzed and compared. Different LAF treatments are performed with Lactobacillus plantarum, Lactobacillus casei and mixed strains of probiotics. The protein quality of treated and untreated protein sample is analyzed by the Bradford protein assay and sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Evolution of functional properties including emulsifying properties, foaming properties, water holding and oil binding capacities of samples with different times of lactic acid fermentation treatments are also analyzed. Based on the experimental results, the water-soluble protein content decreased with the increase of fermentation time, with protein configuration majorly altered beyond 15-hour of fermentation. Thus, a 10-hour L. plantarum fermentation was found optimal in eliminating off-flavour while maintaining protein quality and functional properties. For the optimal treatment, around 42% aldehyde and 64% ketone content were removed, and a small amount of alcohol was produced. This change of the aroma compound profile is considered desirable for dairy substitute production. Results from a descriptive analysis sensory test showed that LAF treatment successfully decreased the overall aroma and flavour intensity in PPIs. The results of this study could be used by the Canadian Food Industry for pre-treating pea protein isolates, before using them as an ingredient in plant-based dairy substitutes.

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