Blueberry Skin Research Articles

Catalytic infrared blanching and ultrasound sequential synergistic pretreatment on osmotic dehydration of blueberry

This study investigated the effects of catalytic infrared blanching, ultrasound, and their combined pretreatments on the dehydration of blueberries. The results showed that catalytic infrared blanching for 6 min facilitated the retention of total phenols and total anthocyanins after the osmotic dehydration of blueberries. The polyphenol oxidase relative enzyme activity and hardness were reduced, while the brightness and relative conductivity were increased. Moreover, the solid gain and water loss were significantly increased with the combined pretreatment of catalytic infrared blanching and ultrasound (60, 40, and 40 + 60 kHz). Reducing the contact angle (from 120.8° to 63.5°) may strengthen the ultrasound cavitation. Furthermore, the drying rate, bioactive components, antioxidant capacity, and color of dried blueberries were evaluated. Compared to the control, the retention of total anthocyanin and the brightness increased. Catalytic infrared blanching combined with ultrasound pretreatment was a processing method to improve the osmotic dehydration efficiency of blueberries. This article deals with osmotic dehydration, a method that partially removes water from blueberries. Ultrasound is considered an effective pretreatment for enhancing mass transfer during osmotic dehydration. The waxy coating on the fresh blueberry epidermis, however, greatly reduces the cavitation effect of ultrasound due to an air film between the epidermis and the solution. Catalytic infrared blanching reduces the hydrophobicity of the epidermis. Catalytic infrared bleaching not only inactivates the enzyme activity in blueberries but also reduces the hydrophobicity of the blueberry skin. In this study, catalytic infrared bleaching was first combined with ultrasound for pre-penetration pretreatment of blueberries, which effectively improved water loss and solids increment during the penetration process as well as enhanced retention of blueberry anthocyanins. Highlights CIB reduced the PPO relative enzyme activity and the contact angle. CIB combined with US significantly increased WL and SG. CIB or US pretreatment improved the retention of TAC, TPC, and TFC.

Combined high-throughput and fractionation approaches reveal changes of polysaccharides in blueberry skin cell walls during fermentation for wine production

There have been rare reports about the structure/composition of polymers in blueberry skin and their changes during fermentation for wine production. In this study, the compositional changes occurring in blueberry skin during fermentation were tracked by a combination of cell wall analysis techniques including infra-red spectroscopy, monosaccharide analysis, and comprehensive microarray polymer profiling (CoMPP). The cross-corroborating data revealed that blueberry skin cell wall is particularly rich in xyloglucan. Chemical fractionation analysis indicated that the KOH soluble fraction is a dominant fraction in fermented blueberry skin. Interestingly, the KOH soluble fraction contained abundant epitopes associated with pectin branch chains, indicating tight binding of some enzyme-resistant pectin polymers to hemicellulose. This study provides important implications for the development of effective strategies to extract beneficial substances (such as aromatics, tannins and pigments) from berry tissues during processing.

Postharvest freezing process assessment of the blueberry structure in three acts: Bioimpedance, color, and granulometry analysis

The bioelectrical impedance, cell granulometry and the color of the freeze-thawed blueberries were investigated. The blueberries were subjected to freezing at −18 °C for 135 min, during this process, groups were removed to every 9 min, and stored at 4 °C until further analysis. Bioelectrical impedance, color, pH, total soluble solids and cell granulometry were measured. The characteristics of bioelectrical impedance, cell granulometry and color were analyzed by computational algorithms, which allowed extracting characteristic of blueberries during the freezing process. The results showed progressive loss of the cellular structure during freezing, this behavior was associated with the bioimpedance parameters. The cells damage also influenced color parameters, and cell granulometry. The color followed the direction toward darkness and more intense red-blue tones, which suggest the migration of pigments from the blueberry's skin towards the flesh. In conclusion, evaluation of the color and cell granulometry by computational algorithms with bioelectrical impedance provides a powerful tool for evaluating cell damage in blueberries during the freezing process.

Effects of chitosan coating on freeze-drying of blueberry enhanced by ultrasound pre-treatment in sodium bicarbonate medium

Sodium bicarbonate medium ultrasound pre-treatment can enhance the freeze-drying process of blueberries, but the quality of dried products cannot meet the actual production needs. To yield higher quality products, chitosan coating was applied in blueberry sodium bicarbonate medium ultrasound pre-treatment enhanced freeze-drying process. The improvement effect of different chitosan coating methodologies on the procedure of blueberry freeze-drying, enhanced by ultrasound pre-treatment in sodium bicarbonate medium, was investigated. These include: chitosan solution soaking alone (CH-A), chitosan medium ultrasound treatment (US-CH), first sodium bicarbonate medium ultrasound treatment then chitosan solution soaking (US-NaHCO3 + CH) and first sodium bicarbonate soaking followed by chitosan medium ultrasound treatment (NaHCO3 + US-CH). While the treatments that presoaking in sodium bicarbonate solution (NaHCO3-A), water medium ultrasound treatment (US-W) and sodium bicarbonate medium ultrasound treatment (US-NaHCO3) were used as the control groups. Results demonstrated that ultrasound treatment and sodium bicarbonate soaking have positive effect on improving the freeze-drying characteristics of blueberries, while chitosan coating has a negative effect. Chitosan coating has a significant effect on strengthening limit effect of blueberry skin on juice overflow and weakening moisture absorption capacity of dried blueberry. US-NaHCO3 + CH pretreatment yielded the best results for blueberry freeze-drying.

Biochemical differences in the skin of two blueberries (Vaccinium corymbosum) varieties with contrasting firmness: Implication of ions, metabolites and cell wall related proteins in two developmental stages

The pursuit of firmer and better-quality blueberries is a continuous task that aims at a more profitable production. To this end it is essential to understand the biological processes linked to fruit firmness, which may diverge among tissues. By contrasting varieties with opposing firmness, we were able to elucidate events that, taking place at immature stage, lay the foundation to produce a firmer ripe fruit. A deep analysis of blueberry skin was carried out, involving diverse comparative approaches including proteomics and metabolomics coupled to immunolocalization assays. In‘O'Neal’ (low firmness) enhanced levels of aquaporins, expansins and pectin esterases at the green stage were found to be critical in distinguishing it from ‘Emerald’ (high firmness). The latter featured higher levels of ABA, low methyl esterified pectins in tricellular junctions and high levels of catechin at this stage. Meanwhile, in ‘Emerald’ ‘s ripe fruit epicarp, several mechanisms of cell wall reinforcement such as calcium and probably boron bridges, appear to be more prominent than in ‘O'Neal’. This study highlights the importance of cell wall reorganization and structure, abundance of specific metabolites, water status, and hormonal signalling in connection to fruit firmness. These findings result particularly valuable in order to improve the fertilization procedures or in the search of molecular markers related with firmness.

Freeze-Drying of Blueberries: Effects of Carbon Dioxide (CO2) Laser Perforation as Skin Pretreatment to Improve Mass Transfer, Primary Drying Time, and Quality.

Freeze-dried berry fruits are generally consumed as they are, whole and without peeling or cutting, as the conservation of their original shape and appearance is often desired for the final product. However, usually, berries are naturally wrapped by an outer skin that imparts a barrier to vapor flow during freeze-drying, causing berry busting. Photo-sequence, experimental, and theoretical methodologies were applied to evaluate the application of CO2 laser microperforations to blueberry skin. Under the same set of freeze-drying conditions, blueberries with and without perforations were processed. The results showed that the primary drying time was significantly reduced from 17 ± 0.9 h for nontreated berries to 13 ± 2.0 h when nine microperforations per berry fruit were made. Concomitantly, the quality was also significantly improved, as the percentage of nonbusted blueberries at the end of the process increased from an average of 47% to 86%. From a phenomenological perspective, the analysis of the mass transfer resistance of nontreated fruits, in agreement with reported studies, showed a Type II curvature, with a sharp decrease at low time, followed by a linear increase. In contrast, blueberries with nine perforations depicted a Type III regime, with a saturation curvature toward the time axis. It was demonstrated that CO2-laser microperforation has high potential as a skin pretreatment for the freeze-drying of blueberries.

New methodology to measure in vivo permeance on blueberry (Vaccinium corymbosum) skin: A correlation to quality during storage

Abstract A new methodology to measure the in vivo water permeance ( P w ) of the blueberry cuticle, and its correlation with blueberry quality parameters during storage is presented. Physical surface properties [contact angle ( θ ), surface free energy ( γ S V ), drop volume ( V d ) and P w ] along with quality parameters (soluble solids, firmness, moisture content, and percentages of shriveled blueberries and blueberries with molds) were determined at different storage times. Neither θ nor γ S V changed significantly, showing that the cuticle composition did not changed. Additionally, V d decreased linearly over time, indicating that P w was constant during the measurement; furthermore, P w magnitude decreased after 7 days of storage, indicating a structural change in the cuticle. Although soluble solids, firmness and moisture content did not change during the storage, the percentages of shriveled blueberries and blueberries with molds increased significantly, and both were correlated with P w change. Therefore, this new methodology can be used to measure blueberries quality.

Blueberry muffin baby syndrome – praca poglądowa

Blueberry muffin baby syndrome is a nonspecific skin symptom characterized by the presence of blue-red, purple, small skin lesions with a coherent consistency, size from 1-5 mm, which have historically been described for the first time in newborns with congenital rubella virus infection. Originally, these changes were associated with the presence of persistent fetal dermal erythropoiesis during the fetal period. We now know that the described changes may be related not only to infectious disorders, but also to other disease entities ranging from hematological, vascular and metabolic disorders to neoplastic diseases including neonatal period. The image of skin lesions depending on the underlying disease may be significantly different. To our knowledge, at present there is no generally accepted algorithm for diagnostic and therapeutic procedures in patients with blueberry muffin skin changes. Knowledge about the most common causes underlying the symptom of bluberry muffin baby syndrome is the key to conducting an efficient diagnostic process, establishing a diagnosis and implementing a quick and effective treatment appropriate for the underlying blueberry muffin disease.

Optical properties of blueberry flesh and skin and Monte Carlo multi-layered simulation of light interaction with fruit tissues

One of the major issues of fresh blueberry production is the excessive bruising caused by mechanical impact during harvesting and packaging, which substantially lowers fruit quality and therefore compromises consumer satisfaction as well as the profitability for growers. Spectroscopy and imaging techniques such as hyperspectral imaging have great potential to detect and quantify internal bruises in fruit. It is important to measure the fundamental optical properties of blueberry tissues to better employ spectroscopy or imaging techniques. The aim of this study was to obtain the absorption coefficient (μa), reduced scattering coefficient (μs′), and scattering anisotropy (g) of blueberry flesh and skin in the spectral regions of 500–800 nm and 930–1400 nm and investigate the light propagation model of blueberries using Monte Carlo multi-layered (MCML) simulation. The total reflectance, total transmittance, and collimated transmittance of blueberry flesh and skin with three treatments (non-bruised, 30-min bruised, and 24-h bruised) were collected using a single integrating sphere-based spectroscopic system. Using the collected spectra, the inverse adding-doubling (IAD) method was applied to calculate μa, μs′, and g. Results indicated that the differences between bruised (30 min and 24 h) and non-bruised flesh samples for both μs′ and g were significant from 930 nm to 1400 nm. Microscope images revealed that the differences were caused by the damaged and ruptured cellular structure of bruised flesh. Although μa, μs′, and g showed significant differences between non-bruised and bruised (30 min and 24 h) flesh in the spectral region of 400–700 nm, the MCML simulation results showed that this spectral region is not effective in detecting bruises due to strong absorption and backward scattering of the blueberry skin. In contrast, the absorption effect of the skin in the near infrared range (930–1400 nm) was small, allowing light to penetrate and interact with the flesh. Therefore, the near infrared spectral region is an effective spectral range for inspecting bruised blueberries using either reflectance or transmittance method. This study reported the optical properties of blueberry skin and flesh with varying degree of bruising for the first time and simulated photon interaction with fruit tissues for bruising detection using MCML. These findings would provide guidance to develop non-destructive sensing methods for blueberry internal bruising detection.

Efficacy of UV-TiO2 photocatalysis technology for inactivation of Escherichia coli K12 on the surface of blueberries and a model agar matrix and the influence of surface characteristics

Surface disinfection of fresh blueberries is an important food safety challenge due to the delicate texture and short shelf life of these small fruits. A newly designed water-assisted photocatalytic reactor was developed for disinfection of fruits with a delicate texture and complex surface characteristics. Efficacy of UV-TiO2 photocatalysis was evaluated in comparison with UV alone for inactivation of Escherichia coli K12 (as a surrogate for Escherichia coli O157:H7) inoculated onto the surface of the blueberry skin, calyx, and an experimentally prepared agar matrix that was used as a model matrix. Influence of surface characteristics such as surface hydrophobicity and surface free energy on bacterial adhesion were also investigated. The initial bacterial population on all surfaces was approximately 7.0 log CFU/g. UV-TiO2 photocatalysis (4.5 mW/cm2) for 30 s achieved comparatively higher bacterial reductions of 5.3 log and 4.6 log CFU/g on blueberry skin and agar matrix surfaces, respectively, than 4.5 log and 3.4 log CFU/g reductions for UV alone (6.0 mW/cm2). Total phenolic and total anthocyanin contents of fruits were significantly increased after both UV-TiO2 and UV treatments, compared with water washed control fruits. UV-TiO2 photocatalysis technology is a non-chemical and residue-free method with reduced water usage for surface disinfection of fresh blueberries.

Development of a distilled-like alcoholic drink from blueberry (Vaccinium corymbosum) cv. Brigitta, and sensory analysis

The present study aimed to develop a distilled-like alcoholic beverage using blueberry from the Brigitta cultivar, either juice, skin or the mixture of both components according to the Law of alcohols No 18.455 from Chile, testing the alcoholic grade and sensory attributes such as; flavour, color, aroma and acceptability. The development consisted of two parts. Firstly, an alcoholic fermentation, and secondly, the distillation of the beverage. Before bottling and labelling, the final product was filtrated. Determinations such as; alcoholic fermentation, temperature, density and soluble solids were performed. Resulting values were subjected to analysis of variance and multiple comparison Tukey tests. It is feasible to obtain a dis-tilled alcoholic beverage from frozen blueberries. Sensory attributes better identified for T1: Blueberry juice fermentation, by panelists, were flavour and color. However, liquors from the treatment T3: fermentation blueberry skin, were identified by panelists as having a better aroma.

Phylogeny of bacterial methylotrophy genes reveals robustness in Methylobacterium mxaF sequences and mxa operon construction

mxaF, the structural gene for the methanol dehydrogenase (MDH enzyme), encodes for alpha subunit of the MDH enzyme. This member of the mxa family is required for production of a functional MDH enzyme. Methylobacterium species, pink-pigmented facultatively methylotrophic bacteria (PPFMs), are plant colonizing, methylotrophic bacteria that utilize methanol as a carbon and energy source during phyllosphere and rhizosphere growth. In a previous study that examined the phylogeny of soil and blueberry skin biofilm isolates, mxaF sequence was found to be a more useful indicator of species distinction within the Methylobacterium genus than 16S rRNA gene sequence and that it was not influenced by several environmental properties, including pH. Here, the phylogeny of methylotrophy genes including mxaF is examined to assess the potential for use of mxaF sequence as a biomarker for the Methylobacterium genus. A phylogenetic comparison of 311 archived PPFM and non-PPFM GenBank bacterial sequences of mxaF, xoxF, and generically annotated PQQ-dependent dehydrogenase genes in the methanol/ethanol family was conducted, including 270 mxaF, mxaF′ and mxaF-like sequences. In addition, construction of operons within the mxa gene family was compared using GenBank completed genome sequences to investigate potential horizontal gene transfer (HGT) events within the mxa methylotrophy system. mxaF sequence and mxa gene family operon construction was found to be highly conserved within the genus Methylobacterium as compared to other bacterial genera. The data reveal evidence of HGT events between Methylobacterium species and other bacterial genera as well as the potential for mxaF sequence to be used as a taxonomic indicator for environmental Methylobacterium strains.

Effect of liquid nitrogen pretreatments on osmotic dehydration of blueberries

Fresh blueberries are highly perishable and must be preserved by either freezing or drying technologies. However, moisture impermeability of their skin is a barrier against the moisture diffusion slowing down the drying process. The aim of this study was to investigate the impact of liquid nitrogen pretreatments on osmotic dehydration kinetics of two blueberry species, Vaccinium corymbosum L. and Vaccinium angustifolium Ait, and on the physicochemical quality of dehydrated fruits.The number of immersions in liquid nitrogen was a determinant factor that accelerated water loss. Depending on the blueberry species, a reduction of dehydration time from 45% to 65% was obtained for liquid nitrogen treated samples when compared to control blueberries. Microscopic observations of the blueberry skin before and after the liquid nitrogen pretreatment revealed a decrease of the cuticle thickness, dewaxing of the skin surface and the presence of micro-fissures facilitating moisture and sugar transfer during the osmotic process. The dewaxing of the blueberry skin due to liquid nitrogen immersions was confirmed by wax quantification before and after the cryogenic pretreatments. Osmotic dehydration and liquid nitrogen pretreatments showed a slight decrease in the levels of phenolic compounds and anthocyanins compared to the fresh blueberries.

De novo sequencing and comparative analysis of the blueberry transcriptome to discover putative genes related to antioxidants

Blueberry (Vaccinium spp.) is an important small fruit crop rich in antioxidants. However, tissue-specific transcriptome and genomic data in public databases are not sufficient for an understanding of the molecular mechanisms associated with antioxidants, especially the biosynthesis of anthocyanins. Here, we obtained more than 64million sequencing reads from blueberry skin and pulp using Illumina sequencing technology. De novo assemblies yielded 34,464 unigenes, among them 1236 transcripts and 862 putative transcription factors involved in the main antioxidant biosynthesis pathway were identified. Comparative transcript profiling allowed the identification of 92 differentially expressed genes with potential relevance in regulating the fruit metabolism and anthocyanin content during ripening. A series of qRT-PCR confirmed the high expression level of the anthocyanin pathway genes in the skin of the blue fruit from the in silico study. This sequence collection provides a significant resource for the blueberry research and breeding work.

Abstract 4614: The organic panic

Abstract In today's market place organic foods have become a very popular topic of discussion. Some studies have compared the different benefits of organic foods vs. conventional foods in disease prevention, including cancer. Although differences have been examined, no broad or concrete conclusions have been reached. Studies have shown that consumption of antioxidants can decrease the risk of oxidative damage, degenerative conditions, and cancer. In this study, antioxidant levels between organic blueberries and conventional blueberries were analyzed and compared in their skin, seed, and juice using the Oxygen Radical Absorbance Capacity assay (ORAC). Data indicate that, in each sample category, conventional samples showed higher antioxidant activities overall when compared to organic samples. 15 organic samples and 15 conventional samples were taken for measurement of antioxidant activity. All values are reported as Trolox Equivalents per 100 grams sample (TE/100g). Conventional blueberry skin revealed highest overall antioxidant activity (7258 TE/100g, s=1024), while organic blueberry seed revealed the lowest (494 TE/100g, s=160). Conventional skin (7258 TE/100g, s=1024) revealed higher values than organic skin (3891 TE/100g, s=288). Conventional seed (1308 TE/100g, s=597) revealed higher values than organic seed (494 TE/100g, s=160). Conventional juice (5077 TE/100g) revealed higher values than organic juice (2205 TE/100g, s=276). Student's t-test analysis revealed statistically significant differences between conventional and organic samples in all three groups (organic vs. conventional skin, p=1.3×10-5, organic vs. conventional seed, p=0.008; organic vs. conventional juice, p=0.022). Data from this study suggest that consumption of organic fruits may not provide higher antioxidant protection when compared to consumption of conventional samples; consumption on conventional blueberries may prove to be most beneficial. Further studies on other fruit samples may provide additional insight on the antioxidant benefits of organic and conventional fruits and vegetables. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4614. doi:10.1158/1538-7445.AM2011-4614

Kaolin Affects Blueberry Maggot Behavior on Fruit

This study assessed the effects of Surround (kaolin) on several behavioral parameters of female blueberry maggot, Rhagoletis mendax Curran (Diptera: Tephritidae). First fruit visited, walking, cleaning, and oviposition behavior were quantified in two-choice and no-choice assays where females encountered Surround-treated and untreated fruit of highbush blueberries (Vaccinium spp.). In two-choice assays, females had a propensity (68%) to first visit untreated blueberries. In two-choice and no-choice tests, number of walking bouts and duration of walking bouts were significantly shorter on the Surround-treated than on untreated fruit. Few oviposition attempts on fruit were observed, irrespective of treatments and assays. Chromameter measurements showed significant modification of the blueberry skin color parameters lightness, hue, and saturation between untreated fruit compared with fruit dipped once or twice in a suspension of Surround. Oviposition trials with field-treated fruit showed that blueberries treated with Surround had fewer oviposition scars than the control, and this was more pronounced with weekly applications of Surround. Uneven coating of the fruit by Surround in field applications may have resulted in higher acceptance rates by flies than in blueberries individually dipped and used in laboratory trials.