Effects of cactus pear clone harvest seasons and times on the physicochemical and technological properties of resulting mucilage and biopolymeric films

Cactus pear cladodes, clones 'Miúda' (MIU) and 'Orelha de Elefante Mexicana' (OEM) were harvested at 6 am and 8 pm during the rainy-dry, dry and rainy seasons to evaluate the effect of type of clone and harvest seasons on the physicochemical and technological properties of mucilage as well as the optical, physicochemical, mechanical, thermal and microstructural characteristics of the films obtained. The mucilage of the OEM clone presented a higher content of phenolic compounds, compared to the Nopalea genus, regardless of the season and time of harvest. Furthermore, the dry period resulted in higher carbohydrate levels, regardless of the harvest time. The biopolymeric films produced from the OEM clone harvested in the rainy season and rainy-dry transition showed darker color, better mechanical properties, water barrier, compact microstructure and thermal stability when compared to the MIU clone. Furthermore, harvesting at 6 am provided improvements in the mechanical conditions, permeability and thermal stability of the films of both types of clones studied. These results showed strong environmental modulation, naturally incorporating important macromolecules such as carbohydrates and phenolic compounds, used in the industry in the production of nutraceutical foods, into the mucilage. Furthermore, harvesting cladodes at 6 am in the rainy and transitional (rainy-dry) periods provided better quality biopolymeric films and/or coatings.

Use of the abrasion technique in minimal processing as an alternative to increase purchase acceptability and minimize browning in yam

BACKGROUND

The present study investigated the sensory acceptance, oxidative damage and protection, and possible anatomical-structural damage of cells from the surface of shapes of minimally processed yam. The tubers were minimally processed into the peeled rondelle, dice and 'chateau cut' (chateau) shapes, the latter of which was obtained after performing the abrasion technique. Control treatment corresponded to the rondelle shape with the periderm. The pieces were kept packed at 5 ± 2 °C for 14 days.

RESULTS

Peeled rondelle and chateau were sensorially the most well-accepted yam shapes and achieved the highest purchase intention. The enzymes were partially modulated by the detected H₂ O₂ levels. Oxidative burst lasted longer in the minimally processed tissues than in the control. Polyphenol oxidase activity showed a clear difference in behavior between the minimally processed pieces and the control. Minimal processing induced transient increases in phenolic compounds, for which the expression was lowest in the abraded pieces. On the other hand, these pieces exhibited greater cell collapse on the surface of the amyliferous parenchyma.

CONCLUSION

Based on the results of the trained panel, the abrasion technique is an alternative to provide shapes that are better accepted and marketable, more resistant to browning, and can be stored for up to 12 days. Resistance to browning may be related to a more efficient modulation of enzymatic antioxidant systems and intense deposition of cell debris on the surface of the amyliferous parenchyma. © 2021 Society of Chemical Industry.

Phosphate Fertilization as a Modulator of Enzymatic Browning in Minimally Processed Cassava

This study proposes to relate the increase in phosphorus (P) supply in the soil, via phosphate fertilization, to oxidative damage and protection, phenylpropanoid metabolism, and enzymatic browning in minimally processed cassava. The roots were grown with 0, 60, and 120 kg ha^-1 P₂O₅. The roots were harvested, and the yield and P content in the root, stem, and leaves were quantified. The roots were minimally processed and stored for 12 days at 5 °C. The higher supply of P in the soil increased the P content of roots and stems but not the agro-industrial yields. Roots grown at 120 kg ha^-1 P₂O₅ showed higher detection of hydrogen peroxide, which was accompanied by increased phenolic compounds, soluble quinones, and antioxidant capacity and increased activities of the enzymes superoxide dismutase, catalase, ascorbate peroxidase, polyphenol oxidase, and peroxidase. The present study thus demonstrates the role of phosphorus application, induction of the synthesis of phenolic compounds, and quality of fresh-cut cassava.

Delaying the harvest induces bioactive compounds and maintains the quality of sweet potatoes

We have identified the best harvesting periods, related to higher bioactive compound content and post-harvest quality, for minimally processed sweet potatoes with orange pulp and cream pulp. Quality loss in minimally processed sweet potatoes occurred due to browning in cv. Mãe de Familia and ESAM1 and to whitening in cv. Paraná. Both Mãe de Família and ESAM1 presented higher peroxidase and polyphenol oxidase activities at 120 days, and cv. Paraná contained high levels of provitamin A. β-carotene was the major carotenoid (up to 99%) in orange pulp. All cultivars harvested at 150 and 180 days and minimally processed showed the best visual quality, the highest bioactive compound content, and no microbial infection. Delaying the harvest also increase the antioxidant activity in orange roots, which was associated with a high content of carotenoids and phenolic compounds, resulting in an increase in the nutritional quality of the product. PRACTICAL APPLICATIONS: Postharvest techniques can improve the visual and phytochemical quality of vegetables and extend their shelf life. The present research provides the best harvesting periods for minimally processed cream and orange sweet potato roots with higher postharvest qualities. Delaying the harvest resulted in a product with better visual quality, higher levels of bioactive compounds, which are highly beneficial to health, for example, ß-carotene, and no microbiological contamination. Our results may contribute to improvements in the current knowledge about harvesting times for sweet potato growers who aim to produce high quality, minimally processed products with a longer shelf life.

Association of preharvest management with oxidative protection and enzymatic browning in minimally processed cassava

The aim of this study was to examine oxidative protection and enzymatic browning in the storage of minimally processed cassava and their relationship with population density and harvest age. Population densities were 1.0, 1.25, 1.5, and 1.75 plants m^-2 . After being harvested at 300, 360, or 420 days after planting, cassava were minimally processed and stored at 5 ± 2°C. It was observed that superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) play key roles in the tolerance of young roots to browning. Planting density, however, does not appear to be a key factor modulating the activity of the enzymes studied. PRACTICAL APPLICATIONS: Younger harvested cassava roots, harvested at 300 days, are more tolerant to enzymatic browning. This appears to be in part due to enzymatic activity modulation of the SOD, CAT, and POD enzymes. In addition, it has been demonstrated that agronomic techniques aimed at increasing productivity, such as increasing the planting density of cassava, do not alter the biomarkers of postharvest quality. In summary, evidence that field management may be an efficient approach to improving the conservation of minimally processed cassava is provided. We believe that the findings of this paper will be of great interest regarding the influence of field management on the postharvest quality of freshly cut cassava and will also provide applicable results relating to its production chain.

Effect of multilayer nylon packages on the oxidative damage of minimally processed yam

Abstract Appropriate storage packaging is an important aspect to minimize physiological deterioration and enhance the shelf-life of minimally processed products. Thus, the goal of this study was to evaluate the physiological and biochemical changes associated with the quality loss of minimally processed yam, maintained in two different packages at 5 ± 2 °C. The yam roots were selected, washed and conserved at 8 ± 2 °C for 24 hours. They were then peeled and cut into slices about 3 cm thick and minimally processed. Approximately 300 g of minimally processed yam roots were packed in polypropylene (PP, 4 μm thick) and multilayer nylon (NY, 15 μm thick) 15 cm wide x 20 cm long bags, which were stored at 5 ± 2 °C for 14 days. The minimally processed yam conserved in PP packaging presented fluorescence on the surface of the segments, characteristic symptoms of Pseudomonas spp., and showed higher peroxidase and catalase activities. The nylon packaging was more efficient in reducing oxidative damage and also inhibited polyphenol oxidase activity and decreased the accumulation of soluble proteins, resulting in decreased deterioration during storage. Thus, the quality of the minimally processed yam maintained in NY packaging was conserved for 14 days at 5 ± 2 °C.

Control of browning of minimally processed mangoes subjected to ultraviolet radiation pulses

The pulsed ultraviolet radiation (UV_P) has been used as an alternative strategy for the control of microorganisms in food. However, its application causes the browning of minimally processed fruits and vegetables. In order to control the browning of the 'Tommy Atkins' minimally processed mango and treated with UV_P (5.7 J cm^-2) it was used 1-methylcyclopropene (1-MCP) (0.5 μL L^-1), an ethylene action blocker in separate stages, comprising five treatments: control, UV_P (U), 1-MCP + UV_P (M + U), UV_P + 1-MCP (U + M) e 1-MCP + UV_P + 1-MCP (M + U + M). At the 1st, 7th and 14th days of storage at 12 °C, we evaluated the color (L* and b*), electrolyte leakage, polyphenol oxidase, total extractable polyphenols, vitamin C and total antioxidant activity. The 1-MCP, when applied before UV_P, prevented the loss of vitamin C and when applied in a double dose, retained the yellow color (b*) of the cubes. However, the 1-MCP reduced lightness (L*) of independent mango cubes whatever applied before and/or after the UV_P. Thus, the application of 1-MCP did not control, but intensified the browning of minimally processed mangoes irradiated with UV_P.

The flotation method for detection of tubercle bacilli in sputum smears

Both the flotation smear examination and culture techniques yielded results for detection of tubercle bacilli which were superior to either direct smear examination or to examination of smear from liquefied or liquefied-centrifuged sputum specimens.