Controlling the Three-Dimensional Printing Mechanical Properties of Nostoc Sphaeroides System

The main purpose of this paper is to explore the opportunities for fresh Nostoc sphaeroides (N. sphaeroides) to be applied to 3D food printing. N. sphaeroides is rich in nutrients and its paste possesses shear thinning properties. It was found the product obtained by 3D food printing with fresh N. sphaeroides had poor printability and was easy to collapse. In this study, we compared the addition of different potato starch (2%, 4%, 6% and 8%) to the characteristics of 3D printing of the N. sphaeroides gel system. The results obtained from the rheological analysis showed that the 6% potato starch added to of N. sphaeroides gel can be utilized for 3D food printing. The addition of potato starch increased the viscosity of the mixture so the printed lines were not easily broken, and the “self-supporting ability” of the material itself was enhanced to maintain a good shape without collapse. Texture profile analysis also showed that the 6% starch added printed product had the best gumminess parameter. In order to get a better printed product, the effects of printing parameters (nozzle diameter (Dn), extrusion rate (Vd) and nozzle moving speed (Vn)) on material printing performance and product formability was tested. When Dn, Vd, Vn were = 1.2 mm, 20 mm³/s, 25 mm/s, respectively, the printed product was having similar to the target product, with less breakage and less the changing of shape. Overall results show that 3D printing technology is a rising method for producing N. sphaeroides-based new products.

     

Preparation of Ultrafiltered Rice Bran Extract and Some Factors Affecting its Browning Inhibition in Potato Puree

Abstract

Rice bran extract (RBE) was fractionated by using ultrafiltration techniques. The obtained retentate (R) inhibited the browning of potato puree to a similar extent as RBE and more than it's permeate. The R that was incubated at pH 4.0, 5.0, and 6.0 inhibited the browning of potato puree more than R that was incubated at pH 7.0 or 8.0. Potato puree that was treated with heated R at 80°C for 10 min had a browning value similar to that of puree treated with unheated R and lower than those treated with heated R at 40 or 60°C for 10 min.     

Proteomic characterization and antifungal activity of potato tuber proteins isolated from starch production waste under different temperature regimes

Proteins were obtained from effluent of a starch manufacture by using different isolation temperatures (40, 60, 80, and 100 °C). The proteins, remaining in effluent after treatment of potato juice at 80 and 100 °C differed significantly in composition and in structural stability as well as in trypsin inhibitory and antifungal activities in comparison with the variants of 40 and 60 °C. The protein samples of 80 °C exhibited the highest antifungal activity and its average value of IC₅₀ against five strains of two Fusarium species was determined in average at 0.18 mg ml⁻¹. The 80 °C protein samples consisted predominantly of low-molecular proteins (7–17 kDa) identified as potato tuber protease inhibitors I and II. Predominantly, protease inhibitors II were identified for the protein samples obtained by 100 °C and here we identified 7 spots in comparison with 12 identified for the 80 °C samples. Samples of 40 and 60 °C with low antifungal activities represent high variability of detected and identified proteins. We identified various representatives of aspartic, cysteine, and serine protease inhibitors in both types of samples. These samples also contained Kunitz-type protease inhibitors that were not found in the 80 and 100 °C samples which documented thermal unstableness of Kunitz-type protease inhibitors. Functional stability at high temperatures and antifungal activity of isolated potato protease inhibitors I and II support the potential of this fraction usage in food, feed, pharmaceutical, or agricultural industry and offer new products for starch manufactures. At the same time, utilization of the stable protein fraction of waste deproteinized potato water promotes exploitation of potato starch production resources.

     

Effect of Thermal Treatment on the Physicochemical Properties of Emulsion Stabilized by Gelatin from Black Tilapia (Oreochromis mossambicus) Skin

This study investigated the influence of thermal treatment (30 °C to 110 °C, 30 min) on the physicochemical and rheological properties of an emulsion stabilized by black tilapia (Oreochromis mossambicus) skin at pH 4. The protein pattern of tilapia gelatin did not have any significant difference after the gelatin was heated within a temperature range of 30 °C to 70 °C. However, at 90 °C and 110 °C, denaturation occurred where α-, β- and γ-chains of the gelatin were degraded, leading to a concomitant increase in low molecular peptides. The emulsion stability was investigated through a particle size analyzer, zeta potential, microscopic observation and creaming index. The gelatin emulsion was physically stable at 30 °C to 70 °C with a mean droplet size of less than 13 μm. When the heating temperature was increased to 90 °C and 110 °C, the emulsion showed a pronounced increase in droplet size due to coalescence. The gelatin emulsion heated at 90 °C and 110 °C also displayed instability against creaming after storage at room temperature for 7 days. As the heating temperature increased, the gelatin emulsion exhibited a decrease in apparent viscosity and the flow behavior changed from shear thinning to Newtonian. The rheological data also showed that the storage modulus (G′) of emulsion became more frequency dependent as the heating temperature increased, indicating weak droplet interactions. The tilapia gelatin emulsion was physically unstable when subjected to thermal treatment above 70 °C. The data reported in this study provides useful insight into the formulation of acidic food emulsions that require thermal treatment.

     

Climate change is predicted to alter the current pest status of Globodera pallida and G. rostochiensis in the United Kingdom

The potato cyst nematodes Globodera pallida and G. rostochiensis are economically important plant pathogens causing losses to UK potato harvests estimated at £50 m/ year. Implications of climate change on their future pest status have not been fully considered. Here, we report growth of female G. pallida and G. rostochiensis over the range 15 to 25°C. Females per plant and their fecundity declined progressively with temperatures above 17.5°C for G. pallida, whilst females per plant were optimal between 17.5 and 22.5°C for G. rostochiensis. Relative reproductive success with temperature was confirmed on two potato cultivars infected with either species at 15, 22.5 and 25°C. The reduced reproductive success of G. pallida at 22.5°C relative to 15°C was also recorded for a further seven host cultivars studied. The differences in optimal temperatures for reproductive success may relate to known differences in the altitude of their regions of origin in the Andes. Exposure of G. pallida to a diurnal temperature stress for one week during female growth significantly suppressed subsequent growth for one week at 17.5°C but had no effect on G. rostochiensis. However, after two weeks of recovery, female size was not significantly different from that for the control treatment. Future soil temperatures were simulated for medium‐ and high‐emission scenarios and combined with nematode growth data to project future implications of climate change for the two species. Increased soil temperatures associated with climate change may reduce the pest status of G. pallida but benefit G. rostochiensis especially in the southern United Kingdom. We conclude that plant breeders may be able to exploit the thermal limits of G. pallida by developing potato cultivars able to grow under future warm summer conditions. Existing widely deployed resistance to G. rostochiensis is an important characteristic to retain for new potato cultivars.     

Comparison of temperature effects on the in vitro growth and disease development in potato tubers inoculated with bacteria Pectobacterium atrosepticum,P carotovorum subsp. carotovorum and Dickeya solani

The relationship between the rate of in vitro growth of bacterial isolates of Pectobacterium atrosepticum, P. carotovorum subsp. carotovorum and Dickeya solani and their pathogenicity was investigated in tubers of two potato cultivars at four temperatures ranging from 18°C to 30°C. The rate of in vitro growth was highly positively correlated with the number of rotted tubers (r ranged from 0.91 to 0.93) and with the weight of macerated potato tissue, which, however, was only found for P. carotovorum and D. solani (r = 0.76; r = 0.91, respectively) and not for P. atrosepticum. The weight of macerated tissue increased with the temperature, but significant differences between species of bacteria were observed only at 26°C and above, at which temperatures D. solani was the most aggressive, followed by P. carotovorum and P. atrosepticum. Almost all potato tubers inoculated with bacteria showed symptoms of soft rot at 26°C and 30°C, but the number of rotting tubers at lower temperatures (22°C and 18°C) decreased significantly. The lowest disease incidence, 11% of tubers with symptoms, was observed for the D. solani and cultivar Sonda at 18°C, what was also confirmed in a separate experiment with tubers from four potato cultivars inoculated with the highly aggressive isolate of D. solani. At temperatures from 18°C to 30°C, the differences in disease severity between potato cultivars with various resistance to bacteria increased in line with temperature, while the differences in disease incidence decreased.     

Thermal-aggregation suppression of proteins by a structured PEG analogue: Importance of denaturation temperature for effective aggregation suppression

Development of protein stabilizing reagents, that suppress aggregation and assist refolding, is an important issue in biochemical technology related with the synthesis and preservation of therapeutic or other functional proteins. In the precedent research, we have developed a structured poly(ethylene glycol) (PEG) analogue with triangular geometry, which turns into a dehydrated state above ca. 60 °C. Focusing on this rather lower dehydration temperature than that of conventional linear PEGs, a capability of the triangle-PEG to stabilize proteins under thermal stimuli was studied for citrate synthase, carbonic anhydrase, lysozyme and phospholipase. Variable temperature high-tension voltage and circular dichroism spectroscopic studies on the mixtures of these proteins and the triangle-PEG showed that the triangle-PEG stabilizes carbonic anhydrase, lysozyme and phospholipase that exhibit denaturation temperatures higher than 60 °C, while substantially no stabilization was observed for citrate synthase that denatures below 60 °C. Hence, the dehydrated triangle-PEG likely interacts with partially unfolded proteins through the hydrophobic interaction to suppress protein aggregation.     

Combined effects of fermentation temperature and pH on kinetic changes of chemical constituents of durian wine fermented with Saccharomyces cerevisiae

This study investigated the effects of temperature (20 and 30 °C) and pH (pH 3.1, 3.9) on kinetic changes of chemical constituents of the durian wine fermented with Saccharomyces cerevisiae. Temperature significantly affected growth of S. cerevisiae EC-1118 regardless of pH with a higher temperature leading to a faster cell death. The pH had a more significant effect on ethanol production than temperature with higher production at 20 °C (5.95%, v/v) and 30 °C (5.56%, v/v) at pH 3.9, relative to that at pH 3.1 (5.25 and 5.01%, v/v). However, relatively higher levels of isobutyl alcohol and isoamyl alcohol up to 64.52 ± 6.39 and 56.27 ± 3.00 mg/L, respectively, were produced at pH 3.1 than at pH 3.9 regardless of temperature. In contrast, production of esters was more affected by temperature than pH, where levels of ethyl esters (ethyl esters of octanoate, nonanoate, and decanoate) and acetate esters (ethyl acetate and isoamyl acetate) were significantly higher up to 2.13 ± 0.23 and 4.61 ± 0.22 mg/L, respectively, at 20 °C than at 30 °C. On the other hand, higher temperature improved the reduction of volatile sulfur compounds. This study illustrated that temperature control would be a more effective tool than pH in modulating the resulting aroma compound profile of durian wine.

     

Effect of temperature on the development of the West Indian sweet potato weevil, <Emphasis Type="Italic">Euscepes postfasciatus</Emphasis> (Fairmaire) (Coleoptera: Curculionidae) on an artificial diet

The relationship between temperature and the development of the West Indian sweet potato weevil, Euscepes postfasciatus, on an artificial larval diet containing powdered sweet potato root, was examined at different fixed temperatures from 22 to 31°C. The developmental periods for egg, larvae, and pupae stages shortened in correlation with increased temperature. The thermal constant was 769.2 degree-days and the developmental zero for female and male was 11.1 and 11.7°C, respectively. Although we can rear this weevil at temperatures ranging from 22 to 31°C, rearing temperatures should be kept between 25 and 28°C because the developmental stages were too long at 22°C and the larval period was delayed at 31°C. The basis for these developmental data will be a useful key factor in designing a plan to eradicate the weevil by using a mass-rearing system and SIT.     

Potential of a granulovirus isolate to control <Emphasis Type="Italic">Phthorimaea operculella</Emphasis> (Lepidoptera: Gelechiidae)

In this study a Brazilian granulovirus strain, PhopGV, isolated from the potato tuber moth (PTM) Phthorimaea operculella, was investigated regarding its potential for biological control and in vivo production. The relationship between mortality of P. operculella larvae and virus concentration was determined at different temperatures on potato tubers and susceptibility of P. operculella to PhopGV was also determined on potato leaves. Virulence of PhopGV to P. operculella was not affected by temperatures from 18 to 30°C. The median lethal concentration (LC₅₀) of larvae fed on potato foliage treated with PhopGV was not higher than that verified with larvae fed on treated tubers. Optimal conditions for production of virus-infected larvae were obtained by using the virus suspensions of 41 × 10⁵, 6.3 × 10⁵ and 62 × 10⁵ OBs ml⁻¹ at 18, 24 and 30°C, which resulted in 32.0, 31.4 and 34.8% of infected larvae collected, respectively. The maximum percentage of infected larvae recovered from tubers was not affected by temperature. However, time for production of virus-infected larvae was longer at 18°C and shorter at 30°C. Persistence of PhopGV was determined on stored tubers and we observed that the virus remained effective for at least two months, causing up to 84.2% mortality of P. operculella at 1 × 10⁷ OBs ml⁻¹. The pathogen was also highly virulent to tomato pinworm, Tuta absoluta, inflicting high percentage of mortality, delaying larval growth and inhibiting pupation. This Brazilian PhopGV strain has potential to control PTM larvae on potato tubers at a broad range of temperature and can be produced in vivo using virus-treated tubers.     

Role of the methionine cycle in the temperature-sensitive responses of potato plants to potato virus Y

Plant–virus interactions are greatly influenced by environmental factors such as temperatures. In virus-infected plants, enhanced temperature is frequently associated with more severe symptoms and higher virus content. However, the mechanisms involved in such regulatory effects remain largely uncharacterized. To provide more insight into the mechanisms whereby temperature regulates plant–virus interactions, we analysed changes in the proteome of potato cv. Chicago plants infected with potato virus Y (PVY) at normal (22 °C) and elevated temperature (28 °C), which is known to significantly increase plant susceptibility to the virus. One of the most intriguing findings is that the main enzymes of the methionine cycle (MTC) were down-regulated at the higher but not at normal temperatures. With good agreement, we found that higher temperature conditions triggered consistent and concerted changes in the level of MTC metabolites, suggesting that the enhanced susceptibility of potato plants to PVY at 28 °C may at least be partially orchestrated by the down-regulation of MTC enzymes and concomitant cycle perturbation. In line with this, foliar treatment of these plants with methionine restored accumulation of MTC metabolites and subverted the susceptibility to PVY at elevated temperature. These data are discussed in the context of the major function of the MTC in transmethylation processes.     

The Response of Triticum aestivum Treated with Plant Growth Regulators to Acute Day/Night Temperature Rise

The fluctuation in temperature adversely affects grain development when the climate changes intermittently. This study investigated the effect of high day/night temperatures (34/30 °C, 38/34 °C and 42/38 °C) for two stress durations (24 h and 48 h) on Triticum aestivum. To ascertain the role of plant growth regulator (PGR) in alleviating the deleterious effects of high temperature stress, the combination of various PGRs (e.g., methyl jasmonate, salicylic acid, ascorbic acid, calcium chloride and indole acetic acid) were foliar sprayed twice; one week prior to commencement of anthesis stage and immediately after the exposure to high temperature stress. In general, the high temperature reduces plant growth, grain setting, and 100-grain weight. High temperature stress causes deterioration of plant photosynthetic machinery through a significant decline in energy dissipation, linear electron flow (LEF) and quantum yield of photosystem II (Phi2) which led to plant death. An increase in the antioxidant enzymes activity (SOD, APX, and CAT) was observed at 38/34 °C, while their activity declined sharply at 42/38 °C. Grain setting and filling were completely inhibited in plants exposed to 42/38 °C even when treated with different combinations of PGRs. Salicylic acid along with methyl jasmonate was the most effective PGR combination resulting in significant improvements in Phi2, NPQt, SOD, grain filling and grain protein content under high temperature stress. A strong correlation was observed between LEF and chlorophyll contents against the number of grains per spike and 100-grain weight. In summary, acute day and night temperature stress adversely affected wheat morphological, physiological, and yield traits, while foliar application of PGRs was partially effective in mitigating these harmful changes.

     

The type of thermal feed treatment influences the inositol phosphate composition

The content and composition of inositol phosphate phosphorus (InsP-P) in maize, wheat, barley and heat treated soybean meal, rapeseed meal and sunflower meal was determined by high-performance ion chromatography (HPIC). Approximately 0.88–0.96 of the InsP-P in the feedstuffs was present in the inositol hexaphosphate (InsP₆) form, whereas the rest was in the inositol pentaphosphate (InsP₅) form and for oilseeds a very small amount was present as inositol tetraphosphate (InsP₄). Rapeseed differed from this pattern by having as much as 300 and 60 g InsP₄-P/kg of the total InsP-P pool. The effect of pelleting (90 °C) and extrusion cooking (130–140 °C, 6.5 MPa) on the composition of InsP-P was investigated. Neither treatment had any major effect on the total content of InsP-P in the feedstuffs. However, as indicated by the statistically significant effects on the proportion of the inositol phosphates, extrusion cooking shifted the inositol phosphates from InsP₆-P towards InsP₅-P both in cereals (P=0.002) and in oilseeds (P<0.001), which show a slight degradation of phytate during this treatment. The degradation of InsP₆ to InsP₅ appeared to be unspecific with regard to isomers in all feedstuffs, indicating that the degradation was non-enzymatic, i.e. a result of the high temperature and pressure during the extrusion cooking. The degradation of InsP₆ in the feedstuffs during extrusion is too limited to have any nutritional effect on the availability of phosphorous and minerals.     

Water Crystallisation of Model Sugar Solutions with Nanobubbles Produced from Dissolved Carbon Dioxide

This study was conducted to examine the influence of CO₂ nanobubbles on crystallisation behaviour of water during freezing of model sugar (2–5%w/v) solutions. CO₂ gas was dissolved at 0, 1000, and 2000-ppm concentrations before freezing. Carbonated sugar solutions in 50 mL plastic tubes were immersed in a pre-cooled (−15 °C) ethylene glycol bath and left to freeze at −15 °C for 90 min. When the temperature of the solutions reached 0 °C, ultrasound (US; 20 kHz) was emitted in the bath for 20 s duration through a metal horn transducer. The US wave applied in the ethylene glycol bath was expected to propagate to the sugar solutions in the tube and promote gas bubble formation from dissolved CO₂, which will trigger the ice nucleation. Obtained freezing curves were analysed for nucleation time and temperature, supercooling degree, and time taken for phase change. In general, the CO₂ gas promoted freezing of water, causing a noticeable shift in nucleation parameters. For example, nucleation time of 2000-ppm carbonated water coupled with sonication emission for 20 s (7.8 min) was much shorter than that of controls (pure water without any treatment = 19.1 min and US only = 14.3 min). The former initiated ice nucleation just below sub-zero temperature (−0.2 °C) whereas the onset temperature of controls (pure water without any treatment = −11.3 °C and the US only treatment = −10.3 °C). A similar effect was observed with different model sugar solutions. The current findings can be applied to refine the manufacturing process of ice-cream and frozen desserts by the food industries.

     

Effect of Microalgae (Arthrospira platensis and Chlorella vulgaris) Addition on 3D Printed Cookies

Rheological and textural characteristics of cookie doughs were measured to characterise the effect of two microalgae biomasses additions (Arthrospira platensis and Chlorella vulgaris) in 3D printed cookies. The rheological characteristics determined the addition of microalgae lead to a greater mechanical resistance and a predominance of the elastic component ahead of the viscous component, this behaviour was confirmed by the textural analysis that showed a greater force for the extrusion of microalgae-enriched doughs. Besides, the influence of processing parameters, including filament diameter (26 and 27 mm) and layer height (1.3 and 1.5 mm), on the geometric accuracy of a 3D printed food structure made of cookie dough before and after baking process, was evaluated. The addition of microalgae biomass in dough, for 3D printed cookies, improves the printability in terms of dimensional properties, achieving 3D structures more stable and resistant to baking.

     

Production and characterization of chitosan obtained from <Emphasis Type="Italic">Rhizopus oryzae</Emphasis> grown on potato chip processing waste

Potato chip processing waste of trimmed potato, potato peel and substandard (low-quality) potato chips, obtained from a potato chip processing plant, were used as substrates for chitosan production from Rhizopus oryzae. It was cultured on each waste product at 30 ± 2°C and 70% moisture content for 21 days. Fermented potato peel had the highest yield after 5 days of fermentation. The cultivation condition of chitosan obtained from R. oryzae was optimum for a peel size of less than 6 mesh, 70% moisture content and a pH of 5. Furthermore, the best extraction condition was using 46% sodium hydroxide at 46°C for 13 h followed by 2% acetic acid at 95°C for 8 h. The maximum chitosan yield obtained by these conditions was 10.8 g/kg substrate. Fungal chitosan properties were found to be 86–90% degree of deacetylation, molecular weight of 80–128 kDa and viscosity of 3.1–6.1 mPa s. Therefore, potato peel could be applied as a low cost substrate for chitosan production from R. oryzae.     

Effect of sucrose on dynamic mechanical characteristics of maize and potato starch films

The dynamic mechanical properties of prepared maize and potato starch films were evaluated for mixtures containing 0%, 10% and 15% (w/w) of sucrose at temperatures ranging from 40.0 to 140.0 °C. The spectra of storage modulus (G′), loss modulus (G″), and loss factor (tan δ) of starch films were acquired. Remarkable reduction in the glass transition temperature of maize and potato starch films was observed with the increasing sucrose content. The spectra of storage modulus (G′), loss modulus (G″), and loss factor (tan δ) were measured for the second and third time after two and seven days, respectively. The peaks of loss factor (tan δ) appeared at 59.81 ± 1.86 °C and 95.96 ± 1.67 °C after two-day-storage, but only one peak appeared at 85.46 ± 5.50 °C after seven days. A shifting trend from higher to lower temperature for loss factor was observed after seven days.     

Beneficial developmental acclimation in reproductive performance under cold but not heat stress

Thermal plasticity can help organisms coping with climate change. In this study, we analyse how laboratory populations of the ectotherm species Drosophila subobscura, originally from two distinct latitudes and evolving for several generations in a stable thermal environment (18 °C), respond plastically to new thermal challenges. We measured adult performance (fecundity traits as a fitness proxy) of the experimental populations when exposed to five thermal regimes, three with the same temperature during development and adulthood (15-15 °C, 18-18 °C, 25-25 °C), and two where flies developed at 18 °C and were exposed, during adulthood, to either 15 °C or 25 °C. Here, we test whether (1) flies undergo stress at the two more extreme temperatures; (2) development at a given temperature enhances adult performance at such temperature (i.e. acclimation), and (3) populations with different biogeographical history show plasticity differences. Our findings show (1) an optimal performance at 18 °C only if flies were subjected to the same temperature as juveniles and adults; (2) the occurrence of developmental acclimation at lower temperatures; (3) detrimental effects of higher developmental temperature on adult performance; and (4) a minor impact of historical background on thermal response. Our study indicates that thermal plasticity during development may have a limited role in helping adults cope with warmer - though not colder - temperatures, with a potential negative impact on population persistence under climate change. It also emphasizes the importance of analysing the impact of temperature on all stages of the life cycle to better characterize the thermal limits.     

Proteomic analysis of the adaptation to warming in the Antarctic bacteria Shewanella frigidimarina

Antarctica is subjected to extremely variable conditions, but the importance of the temperature increase in cold adapted bacteria is still unknown. To study the molecular adaptation to warming of Antarctic bacteria, cultures of Shewanella frigidimarina were incubated at temperatures ranging from 0 °C to 30 °C, emulating the most extreme conditions that this strain could tolerate. A proteomic approach was developed to identify the soluble proteins obtained from cells growing at 4 °C, 20 °C and 28 °C. The most drastic effect when bacteria were grown at 28 °C was the accumulation of heat shock proteins as well as other proteins related to stress, redox homeostasis or protein synthesis and degradation, and the decrease of enzymes and components of the cell envelope. Furthermore, two main responses in the adaptation to warm temperature were detected: the presence of diverse isoforms in some differentially expressed proteins, and the composition of chaperone interaction networks at the limits of growth temperature. The abundance changes of proteins suggest that warming induces a stress situation in S. frigidimarina forcing cells to reorganize their molecular networks as an adaptive response to these environmental conditions.