Shelf-life and quality attributes in fresh-cut pear cv. Shahmive treated with different kinds of antioxidants

Use of Coffee Roasting By-Products (Coffee Silverskin) as Natural Preservative for Fresh-Cut Fennel Slices

The coffee roasting by-product, coffee silverskin, represents a serious problem in environmental pollution. Still, it is also an interesting source of chemical compounds that can be recovered and used in the food industry to improve the physical, chemical, and sensory properties of a wide range of food products. This study aimed to evaluate, for the first time, the effect of the coffee silverskin extract (CSE), applied as a dipping treatment, in preserving the storage and the qualitative decay of fresh-cut fennel slices during 14 days of storage at 4 °C. The experimental plan evaluated two dipping solutions (5% and 10%) with coffee silverskin extract and compared them with a conventional dipping in 2% ascorbic acid and a control (water). The use of CSE in the dipping of fresh-cut fennel permitted an increase in the phenolic (chlorogenic and caffeic acids) content for up to 14 days, with good sensory acceptability and physico-chemical and microbiological characteristics. To date, no applications of CSE in this form have been reported, nor has any food by-product extract been investigated for the preservation of fresh-cut fennel, which makes this study a novel contribution to the development of sustainable treatments for minimally processed vegetables.

Application of phytosynthesized silver nanoparticles (SNPs) against Erwinia amylovora causing fire blight disease

The bacterium Erwinia amylovora is responsible for the destructive disease known as fire blight in pear trees. This highly detrimental condition poses a significant threat to the health and vitality of these trees. The existing strategies for managing fire blight disease involve the regular use of copper compounds and streptomycin, particularly during periods when environmental factors are conducive to the spread of the infection. Silver nanoparticles, also known as SNPs, are tiny specks of silver ranging in size from 10 to 100 nm. These particles are created through various chemical and biological processes. Numerous studies have demonstrated their ability to exhibit antibacterial properties against a wide range of human and animal pathogens. In this investigation, the dimensions of SNPs were ascertained by employing aqueous extracts derived from apple, pear, and quince leaves. The average sizes of the SNPs were found to be approximately 30 nm, 38 nm, and 55 nm, apple, quince and pear respectively. The pear mature fruits successfully managed to control the rot caused by the disease-causing E. amylovora. This study shows the viability of utilizing leaves extract from apple, pear, and quince as a suitable medium for the production of silver nanoparticles. These nanoparticles hold potential for effectively managing fire blight disease.

Konjac glucomannan/microcapsule of thymol edible coating reduces okra pericarp browning by regulating antioxidant activity and ROS synthesis

Okra is susceptible to browning during storage. The effects of konjac glucomannan/microcapsule of thymol edible coating (TKL) on antioxidant activity and reactive oxygen (ROS) synthesis of okra during low-temperature storage were investigated. Thymol edible coating of thymol concentration 40 mg/mL (TKL40) had a regulatory effect on okra browning. After 14 days of storage, compared with the control group, the weight loss rate of TKL was reduced by 5.26 %, the hardness was increased by 24.14 %, and the L⁎ value was increased by 31 %. Moreover, TKL40 increased the scavenging capacity of okra for DPPH and ABTS free radicals, and activated catalase and superoxide dismutase activities by promoting the accumulation of total phenolics and flavonoids. TKL40 also reduced the cell membrane damage of okra during low-temperature storage by reducing the increase of malondialdehyde and H2O2 during okra storage. Meanwhile, it delayed the increase of relative conductivity and the production of O2.-, inhibited the activity of polyphenol oxidase in the late stage, so reduced the combination of polyphenol oxidase and phenolics to reduce the browning. Therefore, TKL40 reduces okra pericarp browning by regulating antioxidant activity and ROS synthesis.

Bamboo leaf extract treatment alleviates the surface browning of fresh-cut apple by regulating membrane lipid metabolism and antioxidant properties

BACKGROUND

The effect of bamboo leaf extract (BLE) on controlling the browning of fresh-cut apple stored at 4 °C was investigated. Browning index, H2 O2 content, O2 - production rate, malondialdehyde (MDA) contents, total phenolic content (TPC) and soluble quinone content (SQC), the activities of polyphenol oxidase (PPO), peroxidase (POD), lipoxygenase (LOX), superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX), DPPH (2,2-diphenyl-2-picryl-hydrazyl) and ABTS [2,2-azinobis(3-ethylbenzothiazoline- 6-sulfonic acid)] radical scavenging activities, and the expression of genes related to browning were all investigated.

RESULTS

BLE effectively alleviated the surface browning of fresh-cut apple, accompanied by a reduction in SQC, LOX activity, H2 O2 , O2 - production rate and MDA accumulation. Furthermore, BLE treatment enhanced the TPC, enzymatic (SOD, CAT, APX and POD) and non-enzymatic antioxidant activities. Principal component analysis and Pearson correlation analysis found the browning inhibition by BLE is not through the reduction of phenolic substrates and PPO activity.

CONCLUSION

BLE controls the browning of fresh-cut apple by increasing the antioxidant capacity to scavenge ROS, which could alleviate oxidative damage and maintain the membrane integrity. © 2023 Society of Chemical Industry.

Antioxidant effects of phenolic extract from sugarcane straw and mannan extract from brewer's spent yeast on fresh-cut apples

BACKGROUND

Fresh-cut fruit are convenient ready-to-eat products increasingly demanded by consumers, but highly susceptible to oxidation. To increase the shelf life of these products, this industry is currently facing the challenge of finding sustainable natural preservatives capable of maintaining fresh-cut fruit quality while meeting consumers' expectations regarding health and environmental concerns.

RESULTS

In this work, fresh-cut apple slices were treated with two antioxidant extracts derived from industrial by-products: a phenolic-rich extract produced from sugarcane straw (PE-SCS) and applied at 15 g L-1 , and a mannan-rich extract obtained from brewer's spent yeast (MN-BSY) applied at two concentrations: 1 and 5 g L-1 . PE-SCS, having a brown color, imparted a brownish hue to the fruit and increased the browning rate during storage, and not even the initial robust antioxidant response (high superoxide dismutase, catalase, ascorbate peroxidase and guaiacol peroxidase activities), prevented oxidation. Fruit treated with MN-BSY extract at 5 g L-1 showed lower color loss rate and higher polyphenol oxidase inhibition, while at 1 g L-1 it showed lower firmness loss rate and lower lipid peroxidation after 6 days of storage.

CONCLUSION

The results showed that PE-SCS triggers a potent antioxidant response in fresh-cut fruit and, despite it imparting a brown color to the fruit at 15 g L-1 , it may have potential for application at lower concentrations. Regarding MN-BSY, it generally decreased oxidative stress, but its effect on quality maintenance was dependent on the concentration and, thus, to confirm its potential as a fruit preservative more concentrations must be tested. © 2023 Society of Chemical Industry.

Bioactive Compounds from Fruits as Preservatives

The use of additives with preservative effects is a common practice in the food industry. Although their use is regulated, natural alternatives have gained more attention among researchers and professionals in the food industry in order to supply processed foods with a clean label. Fruits are essential components in a healthy diet and have also been associated with improved health status and a lower risk of developing diseases. This review aims to provide an overview of the main bioactive compounds (polyphenols, betalain, and terpenes) naturally found in fruits, their antioxidant and antimicrobial activity in vitro, and their preservative effect in different foods. Many extracts obtained from the skin (apple, grape, jabuticaba, orange, and pomegranate, for instance), pulp (such as red pitaya), and seeds (guarana, grape, and jabuticaba) of fruits are of great value due to the presence of multiple compounds (punicalagin, catechin, gallic acid, limonene, β-pinene, or γ-terpinene, for instance). In terms of antioxidant activity, some fruits that stand out are date, jabuticaba, grape, and olive, which interact with different radicals and show different mechanisms of action in vitro. Antimicrobial activity is observed for natural extracts and essential oils (especially from citrus fruits) that limit the growth of many microorganisms (Bacillus subtilis, Escherichia coli, Penicillium digitatum, and Pseodomonas aeruginosa, for instance). Studies in foods have revealed that the use of extracts or essential oils as free or encapsulated forms or incorporated into films and coatings can inhibit microbial growth, slow oxidative reactions, reduce the accumulation of degradative products, and also preserve sensory attributes, especially with films and coatings. Future studies could focus on the advances of extracts and essential oils to align their use with the development of healthier foods (especially for meat products) and explore the inhibition of spoilage microorganisms in dairy products, for instance.

Postharvest Losses in Quantity and Quality of Pear (cv. Packham’s Triumph) along the Supply Chain and Associated Economic, Environmental and Resource Impacts

Approximately one third of the food produced globally is lost or wasted along the supply chain. Reducing this would be an important measure to increase the global food supply as the world continues the struggle to feed its people sustainably. Not merely a waste of food, these losses also represent a waste of human effort and agricultural inputs from expensive fertilizers to natural resources as well as contributing to global greenhouse gas emissions. Measuring the extent of, and understanding the reasons for, these losses can assist in developing appropriate measures required to prevent or reduce such losses. Therefore, the objective of this research was to quantify postharvest losses in quantity and quality of ‘Packham’s Triumph’ pears at farm and simulated retail levels. Pears were sampled from two farms in the Western Cape Province of South Africa, the largest deciduous fruit production and export region in Southern Africa. The greatest losses measured along the supply chain were on-farm immediately after harvest, with 18% recorded. The main reasons for on-farm losses were small size (65%), deformity (26%), and chafed peel (9%). After 14 days in cold storage (−0.3 ± 0.7 °C, 81.3 ± 4.1% RH), mean pear losses were 0.86% which increased to 1.49% after 28 days. After 10 days of further storage under simulated market conditions (5.4 ± 0.6 °C, 83.7 ± 2.9% RH), fruit losses were 1.52% during retail marketing and 2.09% during export. Storing pears under ambient conditions (25.1 ± 1.3 °C and 46.6 ± 6.0% RH) resulted in a higher incidence of losses, increasing from 0.90 to 1.55 and 2.25% after 3, 7, and 10 days, respectively. The socio-economic impacts of these postharvest losses amounted to financial losses of between ZAR 492 million (USD 34.1 million according to the conversion rate of 14 April 2021) to over ZAR 831 million annually, and this was associated with the loss of 301 million MJ of fossil energy, 69 million m3 of fresh water and contributed to the emission of approximately 19,690 tons of CO2 equivalent. The fresh water lost could sustain 3.7 million individuals daily for a whole year at a daily minimum usage rate of 0.05 m3 per day while it will require planting 0.5 million trees to sink the 19,690 tons GHG emissions of the pear losses (0.039 metric ton per urban tree planted). Decreasing postharvest losses will conserve resources as well as improve food security and nutrition, objectives of the post-2015 sustainable development agenda led by the United Nations.

Effects of UV-C and Edible Nano-Coating as a Combined Strategy to Preserve Fresh-Cut Cucumber

The objective of this study was to evaluate the effectiveness of a combination of UV-C disinfection treatment and a nano-coating lemon essential oil nanocapsules. The nanocapsules were prepared by ionic gelation with an alginate-pectin wall and the lemon essential oil had a particle size of 219 ± 22 nm and a zeta potential of -7.91 ± 0.18 mV. The lemon essential oil had an encapsulation efficiency of 68.19 ± 1.18%. The fresh-cut cucumber was stored for 15 days at 4 °C. Six formulations of nanocapsules were evaluated, and hydroxypropyl methylcellulose was used as matrix polysaccharide in four coatings. Three formulations were treated with UV-C at 4.5 kJ/m². The results showed that the combination of UV-C and nano-coatings (lemon essential oil = 200 mg/L) increased the shelf life by up to 15 days. Using UV-C and nano-coatings, the ∆E value was 7.12 at the end of the storage period, while the Control samples had an ∆E of 28.1. With nano-coating treatment, the amount of polyphenols decreased by 23% within 9 days. In contrast, with combined UV-C and nano-coating treatment, the amount of polyphenols was reduced by 38.84% within 15 days. The antioxidant capacity remained stable at 459 μmol TE/100 g for the fresh product when the combined treatment was used. A good correlation was also observed between the increasing of the fruit's shelf life and decreasing of its enzymatic activity. The inclusion of UV-C treatment contributed to the reduction in the initial total bacteria at 3.30 log CFU/g and its combination with nano-coatings helped in the control of microbial growth during storage.

Chemistry of enzymatic browning in longan fruit as a function of pericarp pH and dehydration and its prevention by essential oil, an alternative approach to SO2 fumigation

Background

Longan fruit is a rich source of bioactive compounds; however, enzymatic browning of pericarp and microbial decay have limited its postharvest life. SO₂ has widely been used to overcome these limitations; however, due to safety and regulatory concerns, alternative means should be identified. In this study, antioxidant and antimicrobial properties of thymol (TH) essential oil were investigated against the enzymatic browning and decay of longan fruit.

Methods

Fruits were coated with TH (4%) for 5 min, sealed in polyethylene (PE) packages and stored at 4 °C for 42 d. Fruits immersed in distilled water (DW) and stored in PE were used as control.

Results

TH extended the postharvest life of longan to 42 d than 28 d in DW. TH residues decreased from 142 to 11.17 mg kg^-1, while no residues were found at day 42. TH significantly (P ≤ 0.05) reduced the respiration rate, inhibited polyphenol oxidase (PPO) and peroxidase (POD) enzyme activities, sustained high phenols/flavonoids and prevented pericarp browning (BI) than DW. TH also effectively (P ≤ 0.05) maintained the color values, firmness of peel and aril, total soluble solids (TSS), titratable acidity (TA), inhibited decay incidence (DI) and resulted in lower ethanol content than DW. BI as a function of pericarp pH was highly correlated; pH and BI (r = 0. 97), with PPO (r = 0.93) and with water loss (r = 0.99). A high coefficient of correlation of BI was found with the pericarp pH, enzymes, phenolic, water loss and decay incidence with ethanol. TH could be the best alternative to SO₂ and other synthetic preservatives.

Physical, nutritional, and sensory quality of rice-based biscuits fortified with safou (Dacryodes edulis) fruit powder

The reduction of postharvest losses in rice and safou is imperative to increase productivity in their respective value chains. In this study, fine broken rice grains were used to produce rice flour and subsequently rice-based biscuits. The biscuits were further fortified with safou powder, and the physical, nutritional, and sensory quality and stability during storage of the different types of biscuits were analyzed using standard methods. Fine or nonsandy biscuits had peak particle size of 500 µm, while medium (slightly sandy) and large (sandy) biscuits had peak particle sizes of 1,000 µm and 1,400 µm, respectively. The hardness varied from 5.7 ± 2.3 N for biscuits with large particles to 16.1 ± 4.4 N for biscuits with fine particles. Fortification of biscuits with sour safou increased the protein and amino acid content of the biscuits. Tryptophan was absent in both safou and the biscuits produced. There was an increase in phosphorus, potassium, calcium, magnesium, copper, iron, manganese, and aluminum following fortification with safou. Nonsandy biscuits dissolved faster in the mouth (melt) during consumption than the other biscuits although most of the biscuits were perceived to be low in melting and buttery. Nonsandy biscuits were rated as "very good," while slightly sandy and sandy were rated as "good." Safou rice-based biscuits were perceived as "very good," while simple rice biscuits were perceived as "good." Fortification of rice biscuits with safou increased the protein, essential amino acid, and mineral contents of the biscuits with very appreciable taste. These biscuits can be used to help fight protein, iron, and zinc malnutrition and in mitigating postharvest losses of underutilized broken rice and safou especially sour safou.