Search Results (7)

Pumpkin is rich in nutritional value, and it can be eaten as a vegetable or as a staple food, making it popular among modern consumers. However, after fresh cutting, pumpkins are susceptible to moisture loss, softening, microbial contamination, and browning, all of which significantly compromise their quality during storage. Therefore, it is essential to develop effective preservation techniques for maintaining the quality of fresh-cut pumpkins. Nisin, a safe natural preservative, has not yet been studied for use on fresh-cut pumpkins. This study examines the effects of nisin treatment on the quality of fresh-cut pumpkins and then explores preservation mechanisms based on physiological and metabolomic analysis. Results show that 0.4 g/L nisin treatment effectively delays surface browning without impacting odor and maintains microbial safety throughout storage. Additionally, nisin significantly enhances the activities of phenylalanine ammonia-lyase, cinnamate-4-hydroxylase, 4-coumarate-CoA ligase, and cinnamyl alcohol dehydrogenase, thereby promoting the accumulation of total phenols and carotenoids. The result of the Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment of differential metabolites between control and nisin-treated groups reveals that the most significant pathways affected by nisin treatment are amino acid metabolism and phenylpropanoid metabolism, which suggests that nisin enhances preservation by modulating phenylpropanoid metabolism and alleviating amino acid metabolism. This study provides a theoretical basis and offers new insights into improving the storage quality of fresh-cut pumpkins. Full article

Pumpkin (P) production in Santiago del Estero, Argentina, is of high quality. The product is sold whole and fresh, and is traditionally consumed after being cooked in water. Due to its pleasant flavor (semi-sweet), it is widely accepted among consumers, being a potentially versatile product to be consumed fresh or minimally processed (MP). Processing increases food’s susceptibility to microbial spoilage, making it necessary to use sanitizers. In this work, the effect of different application methodologies at different concentrations of rosemary essential oil (REO) on the sensory characteristics and microbiological quality of grated P was evaluated. The product was washed, sanitized, cut, peeled, grated and centrifuged, and then REO was superficially incorporated in two concentrations (4 and 8 μL/mL), applied in three ways: sprayed (TA), immersion (TI) and by strips embedded in EO being adhered to the storage container (TV). The product was subsequently stored at 5 °C in sealed polypropylene bags of 35 μm. In addition, an immersion treatment with NaClO-100 ppm-3 min and a control without any additive were included. Samples were taken at 24 h and 8 days of storage, evaluating mesophilic aerobic microorganisms (MA), psychrophilic (Psy), enterobacteria (E) and mold and yeasts (MY). Sensory evaluation was carried out by trained judges, determining that aroma and flavor were the critical attributes for acceptability. At the end of storage, microbiological analysis showed that REO treatments presented levels of 10⁷ CFU/g, similar to NaCLO treatment, except TI with both concentrations, which was more effective in inhibiting the development of Psy and MY. Regarding aroma evaluation, at 8 days all treatments were acceptable, with the exception of TI and TV (8 μL/mL), while for flavor all treatments were acceptable with the exception of TI for both concentrations. Therefore, the application of TA and TV treatments at the lowest concentration could be considered for further studies to increase the shelf life of MP P. Full article

Fresh-cut pumpkins refer to fresh pumpkin that has been graded, cleaned, peeled, sliced, preserved, and packaged. It has the qualities of freshness, nutrition, convenience, and being 100% edible. However, mechanical damages during the cutting processing can accelerate the quality deterioration, aging, and loss of nutritional values of fresh-cut pumpkins. Nisin, a natural preservative, has been widely used in fruits and vegetables with good preservation effects. To investigate the effect of different concentrations (0, 0.2, 0.4, and 0.6 g/L) of nisin on the quality of fresh-cut pumpkins, the critical indexes involved in weight loss, firmness, color, respiration intensity, reactive oxygen species (ROS) metabolism, ascorbate (AsA)—glutathione (GSH) cycle, and antioxidant capacity were monitored for fresh-cut pumpkins during storage at 4 °C for 10 days. The results showed that 0.4 g/L nisin was the best preservation concentration. Compared with 0 g/L nisin, 0.4 g/L nisin reduced the weight loss rate and whitening rate of fresh-cut pumpkins by 13.53% and 13.61%, inhibited respiration rate by 45.83%, and maintained hardness by 1.18 times. Meanwhile, 0.4 g/L nisin increased the activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) and maintained higher contents of GSH and AsA. It prevented the rapid increase in ROS levels by improving antioxidant capacity, including DPPH, ABTS free radical scavenging rate, and T-AOC (total antioxidant capacity). The collected results showed that nisin has an obvious influence on the quality by regulating physiological and antioxidant activity metabolism. It is envisaged that the combination of nisin and physical and chemical preservation technology will further enhance the quality of fresh-cut pumpkins during storage in the future. Full article

Fresh-cut pumpkin is favored by consumers for its environmental protection, safety, and convenience at home and abroad. To investigate the effect of different wounding intensities (piece, strip and slice, corresponding to 1.90, 3.53 and 6.29 m² kg⁻¹) on the quality of fresh-cut pumpkin, the critical indexes involved in reactive oxygen species (ROS) metabolism, vitamin C-glutathione cycle, phenylpropanoid metabolism and membrane lipid peroxidation were monitored for pumpkin during storage at 4 °C for 6 d. The results showed that with the increase in cutting injury strength, the lightness, whiteness index, respiration rate, ethylene content, lipoxygenase activity and malondialdehyde content of fresh-cut pumpkin increased, while the hardness, sensory quality, appearance and total soluble solid content continuously decreased. The quality deterioration was the most severe in the slice group, while a higher sensory quality was maintained in the piece after 6 d of storage. However, the activity of phenylalanine ammonia-lyase increased and then contributed to the synthesis of the phenolic compound, which resulted in enhancements of 79.13%, 29.47% and 16.14% in piece, strip and slice, respectively. Meanwhile, cutting enhanced the activity of antioxidant enzymes including ascorbate peroxidase, glutathione reductase, superoxide dismutase and catalase, resulting in the enhancement of antioxidant activity in fresh-cut pumpkin. The collected results showed that the wounding intensities have an obvious influence on the quality by regulating physiological and ROS metabolism. Full article

To maintain the shelf life of fresh-cut zucchini flowers, low temperatures and wrapping with plastic film have been used. In this study, storage at 5 °C for 8 days has been studied, using polyester (an oxygen permeability reduction of 63%) and low-density polyethylene (LDPE) with an oxygen permeability reduction of 24%. In addition, the novelty was investigating the possibility of introducing washing into the process, a rather difficult operation given the high sensitivity of this product to handling. The washing of flowers could ease the consumption of fresh-cut zucchini flowers as they are ready-to-use. The following measurements were carried out: respiration rate, color, firmness, pH, and sensory analysis. The findings showed the polyester film allows the best conservation, representing a barrier to gas diffusion and maintaining an atmosphere rich in CO₂ and poor in O₂. The flowers kept a better texture than those wrapped in LDPE. Using polyester film packaging, sensorial and structural characteristics were maintained for a longer period, and the aspect of the ready-to-use fresh-cut zucchini flowers was satisfying until day 5. Full article

The quality and preservability of fresh-cut fruits can be improved by osmotic dehydration (OD). In this study, the impact of Strained Yoghurt Whey (SY Whey) (along with other osmotic solutes) on mass transfer kinetics (water loss, solid gain, water activity decrease), quality attributes (color, texture, sensory characteristics, vitamin C), and microbial stability during OD and subsequent refrigerated storage (5–15 °C) of OD-processed pumpkin cuts was studied. The effect of temperature (35–55 °C), time (10–240 min), and type of osmotic solvent was evaluated to select the optimal processing conditions (55 °C–120 min; WL: 9-99-10.86 g w./g i.d.m. SG: 1.47–1.79 g s./g i.d.m., a_w: 0.89). The use of SY Whey vs. water as solvent enhanced the mass transfer phenomena increasing the solids uptake diffusion coefficient by 20%. Water and whey osmosed samples were of similar quality (32–38% increase of hardness, total sensory quality score: 7.9–8.2/9.0, vitamin C content: 77–81 mg/100 g). At all studied storage temperatures, OD_{SY Whey} samples presented lower quality degradation rates compared to the respective OD_Water samples (e.g., almost half for hardness change). The shelf life of both OD processed pumpkin cuts exceeded 90 days at 5–15 °C (no microbial growth) supporting the applicability of SY whey as novel osmotic solvent. Full article

Pumpkin seeds are a major agricultural waste from the fresh-cut produce industry. The objective of this study was to investigate the drying behavior of untreated, whole pumpkin seeds in a fluidized bed dryer at 50–80 °C (2.87 m/s), with a view to producing a high-quality pumpkin powder from dried seeds. Seeds were dried at 50–80 °C to an average equilibrium moisture value of 0.035 to 0.006 g H₂O/g DM (3.4 to 0.6% wb). Drying occurred in the falling rate period only and drying rate constants ranged from 0.0226 to 0.0900 1/min with corresponding diffusivity values for the first falling-rate period ranging from 4.68 to 18.63 × 10⁻¹⁰ m²/s. The activation energy (E_a)—for the first falling rate period was determined to be 43.9 kJ/mol. Of the nineteen thin layer models tested, the Alibas model could be successfully used as a general model to predict the Moisture Ratio (MR) data for all temperatures investigated. After drying, seeds were blended to produce powders, which were found to be high in fat, crude protein and fiber. Full article