Sprout Inhibition Research Articles

Food irradiation: an effective but under-utilized technique for food preservations.

While food borne pathogens constitute a major public health problem world-wide, food post-harvest losses is considered to be the leading cause of hunger and malnutrition globally. Food irradiation is a process of preserving food in which food are exposed to appropriate doses of ionizing radiation in order to kill insects, molds and other potentially harmful microbes and allergens. The process involves carefully exposing food to a measured amount of ionizing radiation in a special processing room on a conveyor belt for a specified duration. The radiation sources could be gamma ray, electron beam or X-ray. The radiation doses could be high, low or medium depending on the products to be irradiated and the target organism to be eradicated. Irradiation technology has various applications including sprout inhibition in root and tubers, disinfestation in cereals and pulses, reduction or elimination of food borne pathogens in vegetables and animal products and delayed ripening of fruits. All these applications are intended to increase shelf life and eliminate food allegenicity. Despite consumer concern on the safety and quality of irradiated foods, it is gradually gaining acceptance due to increased awareness and the perceived safety and quality as symbolized by the Radura symbol. With the increasing acceptance and commercialization of food irradiation, it could play an important role in solving the problems of food insecurity and food borne illnesses in the world.

Detection of gamma radiation processed onion during storage using propidium iodide based fluorescence microscopy

The determination of absorbed dose in gamma radiation processed onion (treated with 20–100 Gy for sprout inhibition) during storage is an important regulatory requirement to control unfair practices. To address this problem, a microscopy based method was developed using propidium iodide (PI) staining of onion adaxial epidermis. A proportional radiation dose dependent increase in nuclei count was observed during ambient (26 ± 2 °C) and low (2 ± 1 °C) temperature storage. The method was validated and dose of radiation could be determined accurately in stored onions using blind tests. During mechanism studies, boron-dipyrromethene (BODIPY) dye staining and malondialdehyde (MDA) estimation showed dose dependent increase in peroxidation of membrane lipids. The fluorescein diacetate (FDA) stained onion adaxial epidermis showed decrease in fluorescence indicating lowering of physiological activity. Enzyme peroxidase (POD), phenylalanine ammonia lyase (PAL) activities and phytochemicals (phenolics, flavonoids, ascorbic acid and pyruvic acid) did not change significantly with increasing dose of gamma radiation.

Preparation and Characterization of Methyl Jasmonate Microcapsules and Their Preserving Effects on Postharvest Potato Tuber.

Potato tubers tend to sprout during long-term storage, resulting in quality deterioration and shortened shelf life. Restrictions on the use of chlorpropham, the major potato sprout suppressant, have led to a need to seek alternative methods. In this study, the effects of methyl jasmonate (MeJA) solutions and MeJA microcapsules on sprouting and other key quality attributes of the potato tuber were investigated. The results showed that the MeJA solution was most effective at 300 μmol L−1 according to TOPSIS analysis. To prepare MeJA microcapsules, the optimal formulation is with 0.04% emulsifier, 2.5% sodium alginate, 0.5% chitosan and 3% CaCl2. Compared to 300 μmol L−1 MeJA solution, MeJA microcapsules consumed a lower dose of MeJA but demonstrated a better retaining effect on the overall quality attributes of potato tubers. MeJA microcapsules are promising agents for the preservation of postharvest potato tubers.

Ethylene Inhibits Sprouting of Onion Bulbs during Long-term Storage

The protrusion of sprouts is a major cause of loss of dry onions (Allium cepa L.) during extended storage. Sprouting is conventionally suppressed by treating onions with maleic hydrazide (MH) before harvest. More recently, ethylene was reported to inhibit sprout growth in stored onions, but commercial use of ethylene has been limited. Therefore, the objective of this study was to assess the effectiveness of ethylene on sprout suppression of five commercial cultivars of onions during storage and compare its effectiveness with and without MH treatment. Onions treated with MH were stored for up to 9 months at 1 °C in atmospheres with and without ethylene in a series of experiments conducted over six seasons. Differences in sprout elongation and protrusion were observed during storage in air among the five cultivars. Storage in ethylene was effective in inhibiting sprout elongation and root growth of onion bulbs in all cultivars, with concentrations of 7 µL·L−1 ethylene being more effective than 1 µL·L−1 ethylene. Delaying application of ethylene by 4 months was less effective in inhibiting sprout elongation than continuous treatment. Ethylene provided greater sprout suppression than MH treatments alone and could serve as a replacement for MH.

Evaluation of Cellular Uptake and Removal of Chlorpropham in the Treatment of Dunaliella salina for Phytoene Production.

Chlorpropham is a carbamate herbicide that inhibits cell division and has been widely used as a potato sprout suppressant. Recently we showed that the microalga Dunaliella salina treated with chlorpropham massively accumulated the colourless carotenoids phytoene and phytofluene. Phytoene and phytofluene are valued for their antioxidant, UV-absorption and skin protectant properties; however, they are present in very low quantities in nature. The low toxicity herbicide chlorpropham seems a promising catalyst to produce phytoene in large quantities from CO2 and solar energy with D. salina. This study explored chlorpropham uptake by the algal cells, the formation of potential intermediate metabolites, and the removal of residual chlorpropham from harvested D. salina biomass. Algal biomass rapidly concentrated chlorpropham from culture media. However, washing the harvested biomass with fresh culture medium twice and five times removed ~83 and ~97% of the chlorpropham from the biomass, respectively, and retained algal cell integrity. Furthermore, chloroaniline, a common metabolite of chlorpropham degradation, was not detected in chlorpropham-treated cultures, which were monitored every two days for thirty days. Cells treated with chlorpropham for either 10 min or 24 h continued to over-accumulate phytoene after resuspension in an herbicide-free medium. These data imply that whilst Dunaliella cells do not possess the intracellular capacity to degrade chlorpropham to chloroaniline, the effect of chlorpropham is irreversible on cell nuclear division and hence on carotenoid metabolism.

Sprout Suppressants in Potato Storage: Conventional Options and Promising Essential Oils—A Review

Potatoes are a staple in the diet of millions, and constant demand necessitates the storage of large quantities to meet year-round consumption. Potato sprouting during storage is a major problem that leads to lost revenue and food waste, inspiring numerous studies into methods of sprout suppression. As bans on common synthetic suppressants become increasingly widespread, greater attention is turning to organic alternatives including essential oils (EOs) as sprout suppressants. This review presents an overview of physical and chemical means of sprout suppression in stored potato and critically analyzes studies focusing on the use of EOs for sprout suppression. Promising EOs are identified and evaluated for use in fresh, processing, and seed potato storage. Challenges and limitations of EO use in potato sprout suppression are discussed as well as areas of future research.

µQuEChERS Combined with UHPLC-PDA as a State-of-the-Art Analytical Approach for Quantification of Chlorpropham in Potato

Pesticides are chemicals used in agriculture to prevent insects, fungi, weeds, and other pests, from damaging crops. In addition, some types of pesticides are used after harvest as sprout suppressant agents help keeping the quality parameters of crops during storage. Nonetheless, its presence, even at trace levels, in food products is becoming a big challenge regarding human health. The current work aimed to develop and validate a sensitive and high-throughput analytical approach, based on a state-of-the-art microextraction technique—µQuEChERS, combined with ultra-high performance liquid chromatography equipped with a photodiode array detection system (UHPLC-PDA) to quantify isopropyl-N-(3-chlorophenyl) carbamate (chlorpropham), commonly used as efficient sprout suppressant stored potatoes, in raw and cooked potatoes cultivated in different geographical regions of Madeira Island (Portugal). Good results were obtained in terms of figures of the merit of the method, with correlation coefficients (R2) higher than 0.999 and recoveries between 94.5% to 125%. Method limit of detection (LOD) and limit of quantification (LOQ) were 0.14 μg/Kg and 0.43 μg/Kg, respectively, which are much lower than the accepted and legislated requirements by the European Union, which is 20 μg/Kg for chlorpropham. The concentration of chlorpropham in raw potatoes is significantly higher when compared to cooked samples, which revealed that the thermic treatment during cooking had a significant effect on its degradation. A significant decrease (90%, on average) was observed on chlorpropham levels.

Development of fluorescein-based dosimeter for radiation processing applications

Dosimetry forms an inseparable part of radiation processing. Many dosimeters are available to cover wide range of doses used in radiation processing. These include the Fricke, ceric-cerous, alanine ESR Alanine (Electron Spin Resonance Technique), dichromate, and radiochromic films. Low-dose radiation processing applications (<2 kGy) such as insect disinfestation, shelf-life extension, and sprout inhibition use imported dosimeters. At present, radiochromic films/waveguides are used for low-dose applications; however, the dosimeters are costly and subject to sanctions and supply restrictions from country of origin. The present work discusses the development of system that can be used as a routine dosimeter for radiation processing facilities in the dose range of 200–2500 Gy. Iodine is generated by the action of radiolysis products of water on iodide and iodate present. Generated iodine halogenates fluorescein to erythrosine with the help of bicarbonate. Increase in absorbance due to the formation of erythrosine can be related to the absorbed dose and used in routine dosimetric applications. As the change is radiochromic, it advantageously provides a visual indication of dose received.

Irradiation Conditions for Sprout Inhibition in Onions and Potatoes Using Low-Energy X-Rays

Irradiation Conditions for Sprout Inhibition in Onions and Potatoes Using Low-Energy X-Rays

Using cipc and other alternatives to suppress sprout in potato in the UK

Sprouting is one of the major problems in potatoes during storage. Many consumers refuse to eat potato with sprouts. For this reason, treatment with sprout suppressants is vital. Spearmint oil and Ethylene can be used to suppress sprouts. However, spearmint oil is expensive and Ethylene changes potato colour. CIPC is the best chemical in the market that can suppress sprouting effectively at a low cost. CIPC is toxic and dangerous for the environment. However, by wearing protective equipment and displaying relevant signs, the risk to ourselves and other people can be minimised. The risk to the environment can also be minimised by disposing the containers legally to a licensed disposal contractor and avoiding spillage. The case presented is that of a 2000 tonne store of potato in Hereford in the United Kingdom. A CIPC application has been carried out. The result is 99% control.

Evaluating Ecologically Acceptable Sprout Suppressants for Enhancing Dormancy and Potato Storability: A Review.

Postharvest losses are a key stumbling block to long-term postharvest storage of potato tubers. Due to the high costs and lack of infrastructure associated with cold storage, this storage method is often not the most viable option. Hence, sprout suppressants are an appealing option. In most developing countries, potato tubers in postharvest storage are accompanied by a rapid decline in the potato tuber quality due to the physiological process of sprouting. It results in weight changes, increased respiration, and decreased nutritional quality. Therefore, proper management of sprouting is critical in potato storage. To avoid tuber sprouting, increased storage and transportation of potatoes demands either the retention of their dormant state or the application of sprout growth suppressants. This review evaluates the current understanding of the efficacy of different sprout suppressants on potato storability and the extension of potato shelf-life. We also consider the implications of varied study parameters, i.e., cultivar, temperature, and method of application, on the outcomes of sprout suppressant efficacies and how these limit the integration of efficient sprout suppression protocols.

Maleic and l-tartaric acids as new anti-sprouting agents for potatoes during storage in comparison to other efficient sprout suppressants

Inhibiting sprouting of potatoes is an interesting subject needed for potato storage and industry. Sprouting degrades the quality of tuber along with releasing α-solanine and α-chaconine, which are harmful for health. Sprout suppressants, available in the market, are either costly or toxic to both health and environment. So, there is a need for developing countries to explore new sprouting suppressant compound which is cheap, non-toxic and reasonably efficient in comparison to commercial ones. We have established that simple maleic acid and l-tartaric acid are effective sprout suppressing agents. Both can hinder sprouting up to 6 weeks and 4 weeks post treatment respectively at room temperature in dark. These do not affect the quality parameters, retain the moisture content and maintain the stout appearance of the tubers along the total storage period. Thus maleic acid and l-tartaric acid would qualify as alternative, cheap, efficient sprout suppressant for potato storage and processing.

Effect of edible coating on physical and chemical properties of potato tubers under different storage conditions

Storage is known to change the physical and chemical properties of produce. The purpose of this study was to determine the effect of applying edible coatings on freshly harvested potatoes under different storage conditions. The effects of seven edible coating combination formulations with zein, alginate, potato starch, and essential oil on three potato tuber cultivars, Rio Grande Russet (RG), Yukon Gold (YG), and Purple Majesty (PM), were studied over two seasons (2017 and 2018). The treated tubers were stored in three conditions: high relative humidity storage conditions (HRHSC) at 90% ± 5% RH and 5 °C ± 1 °C; low relative humidity storage conditions (LRHSC) at 55% ± 5% RH and 5 °C ± 1 °C; and room temperature. Most of the edible coatings used for potatoes have limited effects on quality properties in the HRHSC, reasonable effects in RG and PM (weight loss and firmness) in LRHSC, and noticeably favorable effects at room temperature in RG and PM (weight loss and sprout inhibition). Alginate with essential oil and potato starch with alginate formulation significantly improved sensory properties in all cultivars. There was no significant change in the levels of total phenolics and reducing sugars due to the application of coatings.

Combining conventional QTL analysis and whole-exome capture-based bulk-segregant analysis provides new genetic insights into tuber sprout elongation and dormancy release in a diploid potato population

Tuber dormancy and sprouting are commercially important potato traits as long-term tuber storage is necessary to ensure year-round availability. Premature dormancy release and sprout growth in tubers during storage can result in a significant deterioration in product quality. In addition, the main chemical sprout suppressant chlorpropham has been withdrawn in Europe, necessitating alternative approaches for controlling sprouting. Breeding potato cultivars with longer dormancy and slower sprout growth is a desirable goal, although this must be tempered by the needs of the seed potato industry, where dormancy break and sprout vigour are required for rapid emergence. We have performed a detailed genetic analysis of tuber sprout growth using a diploid potato population derived from two highly heterozygous parents. A dual approach employing conventional QTL analysis allied to a combined bulk-segregant analysis (BSA) using a novel potato whole-exome capture (WEC) platform was evaluated. Tubers were assessed for sprout growth in storage at six time-points over two consecutive growing seasons. Genetic analysis revealed the presence of main QTL on five chromosomes, several of which were consistent across two growing seasons. In addition, phenotypic bulks displaying extreme sprout growth phenotypes were subjected to WEC sequencing for performing BSA. The combined BSA and WEC approach corroborated QTL locations and served to narrow the associated genomic regions, while also identifying new QTL for further investigation. Overall, our findings reveal a very complex genetic architecture for tuber sprouting and sprout growth, which has implications both for potato and other root, bulb and tuber crops where long-term storage is essential.

Effect of Storage Temperature and Postharvest Tuber Treatment with Chemical and Biorational Inhibitors on Suppression of Sprouts During Potato Storage

Abstract Consumption of ware potatoes in the tropics may be enhanced by storage under conditions that inhibit sprouting, most important of which is the temperature. The effects of storage temperatures (10 °C and 23 °C) and two alternatives to the chlorpropham (CIPC): 1,4-dimethylnaphthalene (DMN) and peppermint oil (PMO), a biorational inhibitor, were evaluated for tuber sprout suppression at postharvest. Tubers of three cultivars – ‘Asante’, ‘Kenya Mpya’, and ‘Shangi’ – with different dormancy lengths were assessed. Storage temperatures and suppressant effects on tuber sprouting, sprout length and sprout numbers per tuber were investigated in replicated storage experiments. Significant differences in sprout inhibition were observed between the two temperatures with suppressive effects higher at 10 °C than in 23 °C. CIPC had the greatest suppressive effect on tuber sprout inhibition at both temperatures. After 24 weeks of storage, the suppressive effects of CIPC at 10 °C was 100% on the three cultivars, whereas all the nontreated tubers sprouted after six (‘Shangi’), twelve (‘Asante’), fourteen (‘Kenya Mpya’) weeks of storage. At 23 °C, the effectiveness of CIPC followed the dormancy period of the cultivars, with ‘Shangi’ recording significantly more sprouted tubers followed by ‘Asante’ and ‘Kenya Mpya’. The inhibition of sprouting by DMN and PMO varied with storage temperatures and cultivars, but were significantly greater than the nontreated tubers. At 10 °C, the effectiveness of DMN treatment was equal to that of CIPC for ‘Kenya Mpya’ resulting in 100% inhibition. In the PMO treatments, complete inhibition of sprouting was observed for 18 weeks on cultivars ‘Asante’, ‘Kenya Mpya’ and 14 weeks on ‘Shangi’. At 23 °C, PMO suppressed sprouts for 14 weeks on ‘Asante’ and ‘Kenya Mpya’ and on ‘Shangi’ for 8 weeks. Storage temperature effects on sprout length and numbers varied with inhibitor type and cultivar. These findings showed that in potato tuber storage, inhibitors can replace low temperature but to an extent depending on the cultivar dormancy character and storage length, thus enabling greater consumption of potatoes in tropical regions.

New insights into the effects of ethylene on ABA catabolism, sweetening and dormancy in stored potato tubers.

Continuous ethylene supplementation suppresses postharvest sprouting, but it can increase reducing sugars, limiting its use as an alternative to chlorpropham for processing potatoes. To elucidate the mechanisms involved, tubers were treated after curing with or without the ethylene binding inhibitor 1-methylcyclopropene (1-MCP at 1 μL L-1 for 24 h), and then stored in air or air supplemented with continuous ethylene (10 μL L-1). Across three consecutive seasons, changes in tuber physiology were assessed alongside transcriptomic and metabolomic analysis. Exogenous ethylene alone consistently induced a respiratory rise and the accumulation of undesirable reducing sugars. The transient respiratory peak was preceded by the strong upregulation of two genes encoding 1-aminocyclopropane-1-carboxylate oxidase (ACO), typical of wound and stress induced ethylene production. Profiles of parenchymatic tissue highlighted that ethylene triggered abscisic acid (ABA) catabolism, evidenced by a steep fall in ABA levels and a transient rise in the catabolite phaseic acid, accompanied by upregulation of transcripts encoding an ABA 8'-hydroxylase. Moreover, analysis of non-structural carbohydrate-related genes revealed that ethylene strongly downregulated the expression of the Kunitz-type invertase inhibitor, already known to be involved in cold-induced sweetening. All these ethylene-induced effects were negated by 1-MCP with one notable exception: 1-MCP enhanced the sprout suppressing effect of ethylene whilst preventing ethylene-induced sweetening. This study supports the conclusions that: i) tubers adapt to ethylene by regulating conserved pathways (e.g. ABA catabolism); ii) ethylene-induced sweetening acts independently from sprout suppression, and is similar to cold-induced sugar accumulation.

Genome-Wide Association and Genomic Prediction for Fry Color in Potato

Potatoes destined for crisping are normally stored above 8 degrees; below this glucose accumulates leading to very dark fry colors and potential acrylamide build up. Unfortunately, sprouting occurs above 4 degrees and impacts product quality, necessitating the use of sprout suppressant chemicals. Therefore, a goal of breeders is to develop potatoes with excellent fry color, which is maintained under storage below 8 degrees. Genomic or marker-assisted selection offers an opportunity to improve the efficiency of potato breeding and thereby assist breeders in achieving this goal. In this study, we have accumulated fry-color data on a large population of potato lines and combined this with genotypic data to carry out a GWAS and to evaluate accuracy of genomic prediction. We were able to identify a major QTL on chromosome 10 for fry color, and predict fry color with moderate accuracy using genome-wide markers. Furthermore, our results provide evidence that it is possible to identify a small subset of SNPs for processing characteristics that can give moderate predictive ability, albeit lower than that achieved with genome-wide markers.

Essential Oil Composition, Antioxidant, Anti-inflammatory, Insect Antifeedant and Sprout Suppressant Activity in Essential Oil From Aerial Parts of Cotinus coggygria Scop.

Present research reports chemical composition, antioxidant, anti-inflammatory insect anti-feedant, and sprout suppressant activity in essential oil from aerial parts of Cotinus coggygria Scop. (syn. Rhus cotinus) growing widely in Uttarakhand, Himalaya. C. coggygria Scop. is commonly known as ‘smoke tree’ or ‘smoke bush’ due to its flowers those give the smoke like appearance. It is an ornamental plant with many medicinal usages. GC/MS analysis identified over 52 compounds, which contributed to 96 % of the total essential oil. The compounds identified were myrcene (39.5 %), pinene (11.4 %), α-terpineol (8.5 %), cymene (5.7 %), sabinene (5 %), spathulenol (2.7 %), β-pinene oxide (2.6 %), globulol (2.4 %) and caryophyllene (1.6 %). Antioxidant activity through DPPH radical scavenging and metal chelating showed that the plant possesses good antioxidant potential (IC50=10.3±0.6 μL) and (IC50=12.6±0.0 μL) respectively. In-vitro anti-inflammatory activity of the essential oil results with IB50=12.3±0.3 μL. Insect antifeedant activity against Spilosoma obliqua Walker and sprout suppressant activity against Raphanus raphanistrum showed results in time and dose-dependent manner.

Carvone Containing Essential Oils as Sprout Suppressants in Potato (Solanum tuberosum L.) Tubers at Different Storage Temperatures

Sprout suppressant capacities of caraway (Carum carvi L.), dill (Anethum graveolens L.), and spearmint (Mentha spicata L.) essential oils containing high levels of carvone were studied at different storage temperatures (5, 10, and 15 °C) and compared to two chemical sprout inhibitors chlorpropham (CIPC) and S-(+)-carvone. Amongst the essential oils tested, caraway oil was the most effective sprout inhibitor and prevented sprouting up to 180 days at all storage temperatures. CIPC treatment in preventing sprouting was very effective only at low-temperature conditions, while its effect diminished at 15 °C and sprouting began after 120 days of storage. Dill oil prevented sprouting effectively at 15 °C for more than 135 days, and less than 20% of tubers exhibited sprouting. Sprout inhibitory effects of peppermint oil and S-(+)-carvone decreased with increasing storage temperature. All treatments significantly decreased weight loss as compared to the control. The weight loss of caraway oil treated tubers was 36.1%, 46.2%, and 49.6% at 5, 10, and 15 °C, respectively, being lower than that of the control. The peelings of tubers treated with essential oils showed lower carvone residue levels than those of S-(+)-carvone applied tubers. The CIPC residue levels of tubers stored at 5 °C were 16 ppm, being greater than the allowed threshold levels in European countries. It was concluded that using caraway and dill oils decreased weight losses substantially and prevented sprouting for long-term storage at up to 15 °C.

Effect of citronella essential oil fumigation on sprout suppression and quality of potato tubers during storage

Effect of citronella essential oil (CEO) fumigation on sprout suppression and quality of potato tubers during storage was investigated. Potato tubers were treated under conditions of single-phase (30 μL L−1, 0–10 d) and dual-phase (30 μL L−1, 0–10 d; 30 μL L−1, 35–90 d) fumigation. Changes in germination rate, weight loss, starch, reducing sugar, gibberellins (GA3), and α-solanine were measured. The results showed that CEO fumigation could control sprouting and improve the quality of potato tubers during storage compared to the non-treated tubers. CEO treatments inhibited the degradation of starch and the increase of reducing sugar content. The production of gibberellins (GA3) was suppressed, and the levels of α-solanine in the skin and flesh of potato tubers were decreased by CEO fumigation. Dual-phase CEO fumigation had a better effect on sprout suppression than single-phase fumigation, and possesses potential for postharvest application.