Packaging and storage condition affect the physicochemical properties of red raspberries (Rubus idaeus L., cv. Erika)

A comparison of raspberry freezing-damage during preservation in isochoric and isobaric conditions

Introduction

Fruits are perishable, thus it's crucial to have an efficient preservation technique that can increase storage time while keeping physical quality and nutritional attributes in order to avoid wastage. The majority of methods for long-term storage require refrigeration.

Methods

In this investigation, we assess the viability of isochoric freezing as a different technique of raspberry (Rubus idaeus L.) preservation. Raspberries were subjected to different storage conditions: isochoric freezing at -4°C, conventional isobaric settings at +3°C (refrigerator), -21°C (freezer), and -4°C with a trehalose solution in a plastic bag. The study assessed changes in weight loss, visual appearance, color, hardness, °Brix values, and pH over a seven-day period.

Results

Key findings reveal that raspberries subjected to isochoric freezing below the freezing point of water experienced minimal weight loss after seven days. Visual appearance, color, hardness, °Brix values, and pH were comparable to fresh raspberries, indicating minimal alteration.

Discussion

These results suggest that isochoric freezing shows potential as a preservation method that maintains the physical and chemical properties of raspberries similar to fresh fruit. Implementing diverse preservation techniques tailored to raspberries may contribute to environmental sustainability by reducing food wastage and the associated environmental impact.

Preparation, physicochemical and application evaluation of raspberry anthocyanin and curcumin based on chitosan/starch/gelatin film

Raspberry anthocyanin (RA) from Rubus idaeus L. (Rosaceae) and curcumin (Cur) from Curcuma longa L. (Zingiberaceae) can effectively improve the physicochemical properties of composite films, and as bioactive pigment components, they can impart pH-responsive properties to the film. In this study, RA and Cur were added to chitosan/starch/gelatin composite film (CSG) to prepare CSG-RA, CSG-Cur, CSG-RA/Cur₈₂ and CSG-RA/Cur₇₃ color films by solution casting method. The color films could change color under different pH conditions and had higher antioxidant activities using ABTS (2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid)) assay. The results from fourier transform infrared spectroscopy and scanning electron microscopy showed that RA and Cur were well dispersed in the CSG matrix and improved the structure of the composite films. The hydrophobic Cur increased the tensile strength from 6 Mpa (CSG) to 14 Mpa (CSG-Cur), but reduced the elongation at break from 55 % (CSG) to 40 % (CSG-Cur). These color films had a good fresh-keeping effect and freshness monitoring, in particular, CSG-RA/Cur₇₃, had the better opacity, water solubility, thickness, moisture content and water vapor permeability than the other films. Briefly, binary pigment films had the potential to become a pH-sensitive indicator/packing film.

Comparative Study of Three Raspberry Cultivar (Rubus idaeus L.) Leaves Metabolites: Metabolome Profiling and Antioxidant Activities

Raspberry (Rubus idaeus L.), known as one of the famous healthy fruits an d are consumed fresh or processed products all over the world. The antioxidation activity of raspberry fruits as well as leaves have been widely investigated. To better understand the metabolite accumulation mechanisms and to develop different functional cultivars, we performed a non-targeted metabolomics analysis using LC-MS/MS to investigate the contents of existing components from three raspberry cultivars, Autumn Britten, Autumn Bliss, and Red Autumn leaves, respectively. The results show multiple differentially accumulated metabolites among three cultivars, especially for the lipids (α-linolenic acid and eicosatetraenoic acid), amino acids and their derivatives (L-cysteine, Phenylalanine), flavonoids (Kaempferol 3-O-rhamnoside-7-O-glucoside, Quercetin 3-glucoside), and vitamins (Biotin, Thiamine, Vitamin K2), etc. The in vitro cellular antioxidant activities of three raspberry cultivars leaves ethanol extracts (RLEE) were also characterized. Through comparison the superoxide dismutase (SOD), glutathione (GSH), catalase (CAT), and reactive oxygen species (ROS) levels before or after RLEE protection of L929 fibroblast cells upon excessive UVB exposure, we evaluated the antioxidation potentials for all three cultivar RLEEs. It turns out the raspberry Autumn Britten leaf extract holds the greatest potential for protecting the L929 fibroblast cells from UVB induced damage. Our study provides theoretical support for screening of active metabolites from three raspberry cultivars leaves, spanning metabolites’ accumulation to cell damage protection, which could be used to refine bioactivity assessment for different raspberry cultivars suitable for antioxidant products extraction.

Towards Impact of Modified Atmosphere Packaging (MAP) on Shelf-Life of Polymer-Film-Packed Food Products: Challenges and Sustainable Developments

In this article, we report in detail the use of protective gases to extend the shelf-life of polymer-film-packed foodstuff and reduce the most typical bacteria and microorganisms that negatively affect the quality and lifetime of a given packaging. This article provides significant information about the most important advantages of using protective gases and examples of gases or gas mixtures which can be used for almost every kind of foodstuff depending on the application. We also discuss how protective gases change the level of microorganisms in food using gases and how the shelf-life of food can be enhanced using correct gases or gas mixtures. The article also provides imperative information on the selection of correct protective gases for specific applications, especially for food production, to preserve against the most typical threats which can appear during the packaging or production process. Packaging innovations can reduce the environmental impact of food and polymer packaging waste by prolonging products’ shelf-lives and by reducing waste along the production and distribution chain and at the household level.

Effect of raspberry extract on wound healing

The main purpose of this study was to investigate the effect of raspberry extract on wound healing and compare it with that of ellagic acid. The elimination of excess free radicals was the key to preventing wound inflammation; cellular antioxidation activity was evaluated using an oxidative stress damage cell model. Cell proliferation ability was measured using the WST-1 assay, and the migration capacity was determined using the wound scratch assay. A mouse wound model was used to verify the effect of raspberry extract on wound healing. The cellular antioxidant activity of the extract ((50.31±3.17) μg/mL) was slightly lower than that of ellagic acid ((44.59±2.38) μg/mL). The results of a cell proliferation assay showed that both raspberry extract and ellagic acid at 5 μg/mL could significantly (P<0.01) promote the proliferation of HaCaT cells. After culturing for 24 h and 48 h, the cell healing rates of the extract were (41.11±0.38) per cent and (68.88±2.51) per cent, respectively, whereas the corresponding rates of ellagic acid were (39.01±2.40) per cent and (70.33±0.89) per cent; hence, there were no significant differences between them (P>0.05). The wound areas of mice fed low, medium, and high doses of raspberry extract for 14 days were 1.66, 1.41, and 1.24 mm2, respectively, which were significantly lower than that of the blank control group, 2.18 mm2 (P<0.05). These findings indicate that raspberry extract and ellagic acid exhibit similar antioxidant capacities and equivalent cell proliferation-promoting capabilities. In the mouse test, raspberry extract effectively promoted a reduction in wound area. This work demonstrates the potential of raspberry extract in wound healing, suggesting a promising application of raspberry resources in the fields of functional foods, cosmetics, and medicine.

Effect of Different Modified Atmosphere Packaging on the Quality of Mulberry Fruit (Morus alba L. cv Kokuso 21)

The control of temperature and gas composition is essential to maintain the fresh flavor and quality of perishable fruits like mulberry. This study presented a modified atmosphere experiment (MAP) for fresh fruit showing the potential benefits of innovative gas mixing with argon. The effects of MAP were studied on the physicochemical and qualitative attributes of mulberry preserved at 4 ± 1°C and 90 ± 5% R.H. Fresh mulberries were packaged with different gas combinations: MAP1 (4%O₂+6%CO₂+90%N₂), MAP2 (10%O₂+5%CO₂+85%Ar), CTR1 (20.9%O₂+0.04%CO₂), and CTR2 (10%O₂+5%CO₂+85%N₂). Changes in quality parameters were evaluated after 0, 4, 8, and 12 days of storage. Mulberries packaged with MAP had a lower weight loss than CTR samples which lost more than 80% of their initial weight. Furthermore, the results showed that the argon treatment was the best in keeping the fruit juice content, preserving its structure. Despite not showing great differences with MAP1 treatment, Ar allowed to maintain high TSS up to 8 storage days, slowed CO₂ production. The sensory profile of mulberry fruit was not significantly affected by storage in modified atmospheres, and the production of potential unpleasant odors in MAP2 could not be perceived. The results of this study confirm that this innovative approach, using MAP technology, has a potential use in maintaining mulberry fruit quality for a longer time.

Effects of calcium chloride treatment on softening in red raspberry fruit during low-temperature storage

Fruit softening is an inevitable event during ripening of red raspberry fruit even when stored at low temperature. In this research, the effects of CaCl2 treatment on softening of red raspberry during storage at 4°C were studied. The results indicated that CaCl2 treatment effectively delayed the decrease of firmness and reduced the respiration rate of red raspberry fruit during storage. The CaCl2-treated fruit maintained higher protopectin content and lower soluble pectin content compared with controls. The cellulose and starch contents in the fruit treated with CaCl2 kept higher than in the control during storage. Moreover, CaCl2 treatment decreased activities of polygalacturonase (PG), pectin methylesterase (PME), and cellulase (Cx) mainly at the early stage of softening. Application of CaCl2 lead to the decreased activities of amylase (AM) and β-galactosidase (β-gal) compared with controls during the entire storage periods. These results indicated that CaCl2 treatment might delay postharvest softening of red raspberry fruit stored at low-temperature by retarding cell wall degradation and starch hydrolysis. PRACTICAL APPLICATIONS: Red raspberry fruit is very popular with consumers because of its high-nutritional value and anticancer effects. However, it has a very short postharvest life and softens easily even when stored at low temperature, which limits its distribution to distant market. Our data indicated that CaCl2 treatment delayed postharvest softening of red raspberry fruit stored at low temperature. The results could provide preliminary yet essential information to research community to further study the molecular mechanisms of softening in red raspberry fruit, and also provide reference data for maintaining quality of postharvest red raspberry fruit.

The Influence of Film and Storage on the Phenolic and Antioxidant Properties of Red Raspberries (Rubus idaeus L.) cv. Erika

In this paper, the effect of the packaging material and storage method on red raspberries produced at Reggio Calabria (Italy) was studied. For this purpose, the fruits were stored immediately after harvest in different conditions: in the fridge at 1 °C and in the freezer at -20 °C, using different packaging materials, two new patented films (nanoactive A) and (nanoactive B), one common packaging film (polyethylene terephthalate), and other fruits were left without any packaging material. Chemical parameters were analysed at harvest to have the initial characteristics without any conditioned storage and to distinguish the post-harvest effect on the fruits, then daily for storage in the fridge and monthly for storage in the freezer. The aims of our project were first to determine the qualitative characterization of these red raspberries, the optimization of their shelf-life during time in the fridge or freezer, using the different types of packaging materials and finally to highlight the usefulness of the new patented packaging materials. Nanoactive A film showed the best shelf-life in the fridge, and after 14 days the values, given as mg/100 g fresh weight, were: total phenolics (166.70), monomeric anthocyanin content (50.82), flavonoids (24.64), ascorbic acid (32.42), and 1, 1-diphenyl-2-picrylhydrazyl (DPPH) assay (95.93).

Convective Drying of Fresh and Frozen Raspberries and Change of Their Physical and Nutritive Properties

Raspberries are one of Serbia's best-known and most widely exported fruits. Due to market fluctuation, producers are looking for ways to preserve this fresh product. Drying is a widely accepted method for preserving berries, as is the case with freeze-drying. Hence, the aim was to evaluate convective drying as an alternative to freeze-drying due to better accessibility, simplicity, and cost-effectiveness of Polana raspberries and compare it to a freeze-drying. Three factors were in experimental design: air temperature (60, 70, and 80 °C), air velocity (0,5 and 1,5 m · s^-1), and state of a product (fresh and frozen). Success of drying was evaluated with several quality criteria: shrinkage (change of volume), color change, shape, content of L-ascorbic acid, total phenolic content, flavonoid content, anthocyanin content, and antioxidant activity. A considerable influence of convective drying on color changes was not observed, as ΔE was low for all samples. It was obvious that fresh raspberries had less physical changes than frozen ones. On average, convective drying reduced L-ascorbic acid content by 80.00-99.99%, but less than 60% for other biologically active compounds as compared to fresh raspberries. Convective dried Polana raspberry may be considered as a viable replacement for freeze-dried raspberries.