Stored Tubers Research Articles

Carbohydrate enzymes related to cold-induced sweetening and tuber storage in potato genotypes

ABSTRACT The roles of carbohydrate enzymes in cold-induced sweetening (CIS) and long-term tuber storage are not fully understood. This study analyzed enzyme activities in ‘Lady Rosetta’ (CIS-resistant and storable), ‘Kufri FryoM’ (CIS-resistant with regular storage), and ‘MS/8 1148’ (CIS-susceptible with regular storage) potatoes stored at 4°C for 0, 20, 120, and 150 days. CIS increased until 20 days, particularly in the basal ends of ‘MS/8 1148.’ Enzymes like sucrose synthase (breakdown), starch phosphorylase, and UDP-glucose pyro phosphorylase were positively correlated with CIS in ‘MS/8 1148.’ Starch levels were lower in ‘MS/8 1148’ at 20 days but increased in other genotypes. During extended storage, bound starch synthase and starch phosphorylase increased steadily up to 150 days, while soluble starch synthase peaked at 120 days. Sucrose phosphate synthase emerged as a critical marker for CIS resistance. Bound starch synthase and starch phosphorylase were identified as essential markers for long-term storage in potatoes.

Physicochemical characterization of seeds and aril of Renealmia aromatica (Aubl.) Griseb

The Amazon has great biodiversity, being inhabited by indigenous peoples since time immemorial, as well as being home to traditional farmers, settlers, riverine dwellers, people responsible, in large part, for the conservation of biodiversity through the cultivation and storage of grains, tubers, roots and seeds. Among the numerous species cultivated and managed by the Amazonian peoples, we approach, in this work, the species Renealmia aromatica (Aubl.) Griseb., belonging to the Zingiberaceae family. The objective of this article is to present physicochemical aspects of the fruits of Renealmia aromatica (Aubl.) Griseb. aiming to emphasize its alimentary potential and nutritional value.This work consisted of harvesting the fruits of mother plants located in the experimental garden of the Universidade Federal do Acre – UFAC. The analyzes were carried out at the Unidade de Tecnologia de Alimentos – Utal of UFAC – Campus Rio Branco. The variables analyzed were protein, ascorbic acid (vitamin C), titratable acidity, moisture and ash (fixed mineral residue) according to the methods for physicochemical analysis of foods from the Instituto Adolfo Lutz. In the aril and in the seed, protein contents of 7.97% and 6.67% were found, respectively. As for lipids, the highest concentration was observed in the seeds, with a content of 6.76%. The aril showed a satisfactory level of vitamin C (182,81 mg/100g). With a high concentration of lipid, the seeds had a total caloric value of 335,56 kcal/100g. Thus, the seeds and arils of R. aromatica have alimentary and nutritional potential, being the seeds used for the production of edible oil or condiment, and the aril, rich in vitamin C, used in alimentation. This, although already used in food, is still restricted to indigenous peoples and traditional communities.

Smallholder farmers’ participation in Cassava value addition practices: What drivers matter in Ghana?

Cassava is a major staple food often promoted in Ghana. Cassava farmers in Ghana face several challenges, including high post-harvest losses and low prices due to low-value addition. Available literature on cassava value-addition practices (CVAPs) focuses more on processing due to the perishability of the crop. Moreover, the awareness of farmers and the extent of their participation in CVAPs are not known. This study aimed to identify the factors that influence cassava farmers' awareness, participation, and the extent of their involvement in processing and other CVAPs. Smallholder cassava farmers (n = 217) were sampled in the Awutu Senya West District in the Central Region of Ghana, using proportionate stratified sampling technique. Data were collected using a structured interview schedule and analysed using Multinomial regression and Cragg Double Hurdle Model. Results showed that farmers were aware of the CVAPs and viewed them as very relevant activities they could engage in to improve the marketability of their produce. About 65% were involved in at least 2 of the CVAPs. The major CVAPs that farmers engaged in were strategic sale of tubers to processors, retailers, or consumers; storage of tubers; and collective transportation of cassava products. Farmers' age, sex, household size, off-farm income, total yield, access to credit, market information, and perceived relevance of CVAPs significantly influenced their participation in CVAPs. The extent of participation was, however, influenced by sex, household size, access to processing equipment, and market information. To boost CVAPs among cassava farmers in Ghana, policies should be directed by agricultural extension services and financial institutions towards enhancing farmers’ access to market information and processing equipment. They should also provide financial literacy training to encourage increased investment by farmers in cassava production, processing, and marketing. Addressing gender dynamics within cassava value chain activities should also be a focal point in these initiatives.

Integrative Phytohormone and Transcriptome Analyses Reveal the Inhibitory Mechanism of Ethylene on Potato Tuber Sprouting at Room Temperature

As a commercial potato sprout suppressant, ethylene (Eth) is usually used under a low temperature for long-term storage of potato tubers. However, in many cases, potato tubers are usually transferred from a refrigeration house and sold at room temperature. In the present research, Eth’s inhibitory effects on tuber sprouting at room temperature were investigated. The potential molecular mechanisms of Eth-induced sprout suppression were revealed by phytohormone and transcriptome analyses. Results showed that exogenous Eth significantly suppressed sprout growth in potato tubers during two weeks of storage. The endogenous plant hormone levels of abscisic acid (ABA) and auxin (Aux) were markedly reduced by Eth treatment. Transcriptomic analysis revealed that more transcriptional changes occurred in the early stage of sprouting. The differentially expressed genes (DEGs) assigned to the pathways of plant hormone signal transduction, photosynthesis, starch and sucrose metabolism and phenylpropanoid biosynthesis, which were closely associated with sprouting, were extensively down-regulated by Eth treatment. In addition, the heat map of six hormone signal transduction pathways showed that the expression of most DEGs annotated into the Aux signal transduction pathway was suppressed by Eth treatment, while the expression of many DEGs annotated as ETR (Eth receptor) and ERF1/2 (Eth-responsive transcription factor 1 and 2) in the Eth signal transduction pathway was enhanced by Eth treatment. Taken together, our results indicated that Eth-induced sprout inhibition might be closely related to the suppression of internal Aux production and signal transduction and the activation of Eth signal transduction.

Efficacy of ginger (Zingiber officinale) in controlling fungi causing postharvest deterioration in yam tuber

Yam (Dioscorea sp.) is a popular tuber in Cameroon, where it is grown for both food and income. One of the most challenging aspects of the long-term storage of yam tubers is post-harvest spoilage, often caused by fungi. The use of post-harvest chemicals on yam tubers is not a matter of course. The present study evaluated the efficacy of aqueous extract and powder of Zingiber officinale against fungi associated with the storage rot of yam. The fungi were isolated from two yam cultivars, “Calabar” and “Ghana”, from three localities in Cameroon. The antifungal activity of the aqueous extract and ginger powder was studied in vivo on slices of yam tubers. The results obtained showed that eight fungi were associated with yam tubers and exhibited typical rotting symptoms. The most prevalent and virulent fungus was Penicillium sp., which caused decay volumes of 12.76 cm3 and 8.74 cm3 for “Calabar” and “Ghana” cultivars, respectively. Fungal spoilage was greatly reduced by the application of aqueous extract and ginger powder. The aqueous extract tested at the 30% dose was more effective with up to 80% inhibition. However, the ginger powder was more effective against Penicillium sp., Aspergillus niger, and Colletotrichum sp. associated with rot in the variety “Ghana” with total inhibition (100%). Therefore, the aqueous extracts and powder of Zingiber officinale can be used as a bio fungicide to improve the shelf life of yam tubers.

Deep learning-based characterization and redesign of major potato tuber storage protein

Potato is one of the most important crops worldwide, to feed a fast-growing population. In addition to providing energy, fiber, vitamins, and minerals, potato storage proteins are considered as one of the most valuable sources of non-animal proteins due to their high essential amino acid (EAA) index. However, low tuber protein content and limited knowledge about potato storage proteins restrict their widespread utilization in the food industry. Here, we report a proof-of-concept study, using deep learning-based protein design tools, to characterize the biological and chemical characteristics of patatins, the major potato storage proteins. This knowledge was then employed to design multiple cysteines on the patatin surface to build polymers linked by disulfide bonds, which significantly improved viscidity and nutrient of potato flour dough. Our study shows that deep learning-based protein design strategies are efficient to characterize and to create novel proteins for future food sources.

Evolution of Some Biochemical Parameters during Cold Storage and Their Effect on the Formation of Acrylamide in Fried Potatoes

Background: The province of Ain Defla (Algeria) is known for its high potato production potential. However, many challenges need to be overcome, among them the deterioration of biochemical and organoleptic quality after harvest and during storage of potato tubers. Methods: A study was carried out in this context over two successive years 2019 and 2020, with the aim of determining the degree of physiological evolution of tubers of four potato varieties (Kondor, Bartina, Spunta and Atlas) through biochemical indicators, such as pH, acidity, dry matter, reducing sugars and starch, during cold storage at a temperature of 6°C±2 and for 60 days and 90 days. A qualitative analysis of acrylamide formation under the effect of temperature and frying time was carried out. Result: Kondor revealed the highest pH value before and during storage. A progressive decrease in dry matter and starch as a function of storage time was detected for all varieties studied, notably Spunta and Atlas. The Spunta variety showed significant amounts of reducing sugars during 60 days of storage. Acrylamide formation was intense at 160°C for 4 minutes of frying in both Spunta and Kondor varieties. However, Kondor showed greater resistance to enzymatic browning (acrylamide) than Spunta under the same empirical conditions.

Effect of Plant Growth-Promoting Rhizobacteria (PGPRs) on Tuber Storage of Two Potato Varieties

El-Allaoui N., A. Douira, A. Benbouazza, M. Ferrahi, E. Achbani and K. Habbadi. 2024. Effect of Plant GrowthPromoting Rhizobacteria (PGPRs) on Tuber Storage of Two Potato Varieties. Arab Journal of Plant Protection, 42(2): 229-233. https://doi.org/10.22268/AJPP-001242 The potato (Solanaceae family) is a cultivated plant primarily valued for its tubers, which serve as a crucial food source for numerous populations worldwide. Losses due to postharvest diseases are significantly high and need to be reduced. To preserve tuber quality without relying on chemical treatments, the application of plant growth promoting rhizobacteria (PGPR) has been employed as a means to extend the shelf life of potato tubers. The objective of this study was to assess the effect of eight PGPRs on the conservation of two potato varieties Siena and Bellini. This was carried out in two trials; in the first trial, thirty potatoes of the Siena variety were treated with PGPRs and covered with wheat straw, and in the second trial, 160 potatoes each of the two varieties Siena and Bellini were treated with PGPRs but covered with wheat straw and black plastic. Results obtained indicated that several PGPR strains performed favorably, the most promising of which was the Aureobasidium pullulans (Ach1.1) strain that kept 50% of the treated potatoes healthy for one month in the first trial, and 30% for six months in the second trial, as compared to the negative control where 100% of the potatoes showed signs of rot in both trials. It can be concluded from this study that the Ach1.1 strain of Aureobasidium pullulans could be a promising post-harvest bio-control treatment. Keywords: PGPRs, conservation, post-harvest, potato, rot

Potato tuber yield and quality under potassium and magnesium addition on top of the nitrogen and phosphorus fertilization

The aim of the study to investigate the effect of individual or combined K and Mg addition on potato tuber yield and quality along the gradient of soil and environmental conditions, which was formed by the five experimental plots in the forest-steppe one of West Siberia. Location and time of the study. Microplot field experiment with moderately early potato cultivar Jelly with three fertilization treatments (N100P60, N100P60+K100 and N100P60+K100+Mg100) was setup in five replicates on five experimental plots with agricultural grey soils in the Novosibirsk Region in 2023. Geographical coordinates of the experimental sites varied from 55°15'40" to 54°47'09" NL and from 83°31'42" to 82º37' 56" EL. Methods. Instead of traditional temporal gradient (3–4 years of the experiment at a site) to account for weather variation, with the same purpose we used a spatial gradient, which in addition allowed to assess the effect of soil properties variation among the sites. Soil samples, collected prior to the experiment, were analyzed for organic carbon content, nitrate and ammonium nitrogen, exchangeable phosphorous, potassium and magnesium, as well as soil pH and electrical conductivity. In the course of the experiment air and soil (at 5 and 15 cm depth) temperatures was automatically recorded. At the end of the experiment potato tuber mass and number, as well as the aboveground phytomass, were measured at each microplot. After five months of tuber storage sensory properties (flavour, aroma, colour, mealiness and friability) of boiled tubers were assessed using a Hedonic scale. Analysis of variance, principal components extraction and multiple regression by partial least squares method were performed using Statistica v. 13.1. software. Results. Addition of K at the background NP fertilization (N100P60+K100 treatment) increased tuber yield by 30% and the aboveground phytomass by 40%. Addition of Mg (N100P60+K100+Mg100) did not affect yield properties, but markedly improved potato culinary quality. More than half of the variance of the potato yield properties was accounted for by the variation in soil and environmental conditions of the experimental fields location. Exchangeable Mg, ammonium N and soil pH were the main soil properties, allowing to forecast the current year tuber yield. The contribution of soil and environmental conditions of the experimental fields into the variance of the sensory properties, albeit small, was statistically significant (p≤0,05) for aroma and colour, with the similar trend for flavour and friability (0,05≤p≤0,10). Agrochemical properties, i.e. soil organic carbon, readily exchangeable P and nitrate N contents, as well as soil pH, were the main variables, determining tuber quality for consumers. Conclusions. The study performed on the agricultural grey soil in the forest-steppe zone of West Siberia confirmed the importance of optimizing potato mineral nutrition. Addition of NPK at the balanced rates significantly increased potato yield as compared with NP. Although addition of MG together with NPK did not increase the yield, it markedly improved sensory properties of potato. Some soil properties and temperature conditions, found to determine the yield (effective soil fertility), can be used in prognostic models for potato tuber yields and quality.

The effect of the ethylene phytohormone on the growth, development and yield of potatoes

. In 2021–2022, experiment on growing potatoes with preliminary seed tubers storage in the environment of the ethylene phytohormone was conducted at the Russian Potato Research Centre. The aim of the research was to determine the influence of seed tubers treatment with phytohormone ethylene on growth, development and yield of potatoes, taking into account the preplant doses of mineral fertilizers and variety specificities. Ethylene appliance at a concentration of 15 ml/m3 was carried out in the potato storage from November till the end of April at a temperature 4 0C and a relative humidity 90-95%. As a result of research, it was found that the use of ethylene while seed potatoes storing of varieties Grand and Vympel provided the 2-3 days earlier emergence of seedlings; an increase in plant height by 1.5-12.4%; an increase in number of stems per plant by 11.4-26.3%; an increase in leaf surface area by 5.5-11.3%. The total potato yield due to ethylene appliance increased by 5.6-12.9% or 1.3-1.8 t/ha (Grand) and by 5.6-27.7% or 1.1-3.6 t/ha (Vympel). The most significant increase of yield was noted when growing potatoes with mineral fertilizers dose N30P30K45. Ethylene seed treatment did not have a significant effect on the percentage of commercial tubers. The Grand variety, compared with the Vympel, turned out to be more responsive to the use of high doses of mineral fertilizers. It was found that the most significant factor that provided an increase in total yield by 4.2-12.4 t/ha or by 25.3-93.9% (depending on the variety and ethylene treatment) was the dose of fertilizers.

Reduced glutathione and raffinose lengthens postharvest storage of cassava root tubers by improving antioxidant capacity and antibiosis

Cassava is an ideal food security crop in marginal and drought environment. However, the post-harvest storage of cassava is urgent problem to be resolved. In this study, the storage tolerant and non-tolerant cassava were screened by measuring the change of Peroxidase (POD), Superoxide dismutase (SOD), Catalase (CAT) and Malondialdehyde (MDA) in seven cultivars of cassava. Compared with other cultivars, the cultivar of SC14 showed the highest level of SOD, MDA and POD respectively at 0 day, 12 day and 9 day postharvest while exhibited lowest level of CAT at 0 day postharvest, indicating the strongest antioxidant capability and storage tolerance. In contrast, GR15231, termed as storage non-tolerance cultivars, showed lowest SOD and POD at 12 day and kept a relative high level of CAT at 12 day post-harvest. In addition, SC14 has higher level of starch and dry substance than GR15231. Mass spectrum was performed for SC14 and GR15231 to explore the key metabolites regulating the storage tolerance of cassava. The results showed that the expression of glutathione (reduced) and raffinose was significantly decreased at 12 day post-harvest both in tolerant SC14 and non-tolerant GR15231. Compared with GR15231, SC14 showed higher level of raffinose both at 0 and 12 day post-harvest, indicating that raffinose may be the potential metabolites protecting SC14 cultivar from deterioration post-harvest. Additionally, raffinose ratio of SC14a/SC14b was five times less than that of GR15231a/GR15231b, reflecting the slower degradation of raffinose in SC14 cultivar compared with GR15231 cultivar. In conclusion, the antioxidant microenvironment induced by reduced glutathione and higher level of raffinose in SC14 cultivar might be the promising metabolites to improve its antioxidant capacity and antibiosis and thus maintained the quality of Cassava root tubers.

Impact of dormancy periods on some physiological and biochemical indices of potato tubers.

Storage of potato tubers is an essential stage of the supply chain, from farm to consumer, to efficiently match supply and demand. However, the quality and yield of potatoes are influenced by physiological changes during storage. This study tested the physiological and biochemical indices in three potato varieties (YunSu 108, YunSu 304 and YunSu 306) during their dormancy periods. Three potato varieties with different dormancy periods were used to follow changes in starch, protein and several enzymes during storage. The starch and sugar content of the long-dormant variety (YunSu 108, LDV) were stable, whereas those of the short-dormant variety (YunSu 306, SDV) were variable. Starch synthase activity in the three varieties was initially high, then decreased; the starch content of LDV was relatively stable, that of the medium-dormant variety (YunSu 304, MDV) increased with storage time and peaked at sprouting, and that of SDV was low but variable. The sucrose synthase activity of LDV was significantly higher (p<0.05) than MDV and SDV in the middle storage period. Two spikes were observed in the invertase activity of SDV, whereas those of MDV and LDV were stable. The reducing sugar content of LDV increased significantly before sprouting, that of MDV slowly decreased and that of SDV dropped sharply. During the whole storage period, pectinase activity in LDV did not change significantly, whereas pectinase in MDV and SDV decreased. The cellulase and protein contents initially increased and then decreased in LDV, and steadily decreased in MDV and SDV. The metabolic indices related to starch and sugar in the LDV were relatively stable during storage, whereas those of the SDV varied greatly. SDV showed increased sucrose, reducing sugars and cellulose; LDV PCA plots clustered in the positive quadrant of PC1 and the negative quadrant of PC2, with increased protein, sucrose synthase and starch; MDV had increased soluble starch synthase.

The Content of Carotoids and the Expression Profile of Carotenoid Biogenesis Genes during Long-Term Cold Storage of Potato Tubers

Carotenoids are secondary metabolites that are synthesized and stored in all types of plant plastids. These pigments play a significant role in protection against oxidative stress, as well as in the color of flowers and sink organs. Tubers of potato Solanum tuberosum L. synthesize carotenoids, including during post-harvest storage. The state of physiological dormancy and cold stress response are controlled, among other things, by abscisic acid (ABA), which is an apocarotenoid. In this study, we analyzed the expression of carotenoid biogenesis pathway genes (PSY1, PSY2, PSY3, PDS, ZDS, Z-ISO, CRTISO, LCYB1, LCYB2, LCYE, VDE, ZEP, NSY, NCED1, NCED2, and NCED6), as well as genes putatively involved in initiation of chromoplast differentiation (OR1 and OR2), in the dynamics of long-term cold storage (September, February, April) of tubers of potato cultivars Barin, Utro, Krasavchik, Sevemoe siyanie and Nadezhda. It was shown that OR1, and OR2 mRNAs are present in tubers of all cultivars at all stages of storage. The expression profile of all analyzed carotenoid biosynthesis genes during tuber storage was characterized by a significant decrease in transcript levels in February compared to September, with some exceptions. In the period from February to April, the level of gene transcripts changed insignificantly. The biochemical analysis of the carotenoid content in the dynamics of cold storage showed that at the time of harvesting, the highest carotenoid content was in tubers of the cv. Utro; tubers of other cultivars were characterized by a similar amount of carotenoids. During storage from September to April, the total carotenoids changed in a genotype-dependent manner without any trend common to all cultivars.

Sprout-suppressing 1,4-dimethylnaphthalene treatment reduces dry rot infection in potato tubers during postharvest storage

Postharvest losses related to dry rot can reach 60% during long-term storage of potato tubers. Current control methods do not provide an efficient solution to control dry rot, and inducing resistance through elicitors may be a promising way to manage this disease. In this study, we evaluated the ability of 1,4-dimethylnaphthalene (1,4-DMN) and methyl jasmonate (MeJa) to induce resistance to dry rot caused by Fusarium nirenbergiae, using ‘Asterix’ and ‘Challenger’ under refrigerated storage conditions. In vitro and in vivo tests were performed evaluating the volume of infection and the activity of antioxidant and defense enzymes, including polyphenol oxidase, peroxidase, catalase, ascorbate peroxidase, phenylalanine ammonia lyase, lipoxygenase and β-1,3 glucanase. The results reinforce the difference in susceptibility to dry rot between the genotypes, with the ‘Asterix’ and ‘Challenger’ being classified as resistant and susceptible, respectively. The in vivo tests corroborated the findings of the in vitro tests, demonstrating that only 1,4-DMN retarded the growth of F. nirenbergiae. Throughout the progression of the disease, the activity of the defense enzymes revealed a more consistent response regarding the difference in susceptibility between cultivars than in response to the applied elicitors. Therefore, our data suggest that the efficiency of 1,4-DMN in reducing the volume of infection is linked to its direct action on the pathogen and not to the activation of a defense switch via antioxidants and defense-related enzymes. Unlike 1,4-DMN, MeJa did not control potato dry rot.

First report of post-harvest tuber rot of Apios americana Medikus caused by Penicillium expansum in South Korea.

Apios americana Medikus, a perennial vine legume native to North America, is known as 'Indian potato' or 'Apios' for their underground tubers that are used for human consumption in Korea (Choi et al., 2017). These tubers are known to be rich in isoflavones as well as other secondary products to have known several medicinal properties (Chu et al., 2019). The harvested tubers in 2020 were observed to rot during storage of tubers for 4 months at 4°C in the genetic resource storage room at the Bioenergy Crop Research Institute, National Institute of Crop Science, Muan, Jeollanam-do, South Korea. The incidence of rot symptoms with blue mold was less than 1% per 20 kg box. Ten infected tubers were collected from several boxes and the lesions were cut into small pieces, and then surface sterilized in 1.5% NaClO for 2 minutes, followed by rinsing 3 times with sterilized water. To investigate their morphological characteristics, ten isolates were cultured in Malt Extract Agar (MEA) medium at 25° C for 5 days (Pitt and Hocking, 1988). The surface morphology of the mycelium had white or light green fluffy, and completely blue spores were formed after about 5 days. The conidia were one-stage branched with an elliptical shape, about 3.5 to 4.3 × 2.9 to 3.6 (mean 3.8 ± 0.3 × 3.2 ± 0.2) ㎛ in diameter (n=30). Genomic DNAs of the isolates were extracted using Solgent DNA Extraction Kit (Solgent, Daejeon, Korea), and then PCR products of the internal transcribed spacer (ITS1/ITS4) region and the beta-tubulin gene (Bt2a/Bt2b) were sequenced and analyzed (Glass and Donaldson, 1995). The BLASTn showed that the representative isolate had 99% homology with reference Penicillium expansum strain ICMP 2708 (ITS region and TUB2 gene) in NCBI GenBank. The sequences of the isolate were deposited in GenBank as accession numbers MZ636667 and MZ702813 for ITS and TUB2 genes, respectively. Based on the morphological characteristics and molecular analysis, the isolate was identified as P. expansum. Pathogenicity assays of the isolate were also performed using three tubers in three replicates inoculated with spore suspension (concentration, 1×106 conidia/mL) and compared with a control group inoculated with sterilized water. The inoculated Apios tubers were placed in a plastic box maintained in conditions of high humidity at 25°C. Five days after inoculation, the typical symptoms were observed on inoculated tubers, and no symptoms were observed in the control one. P. expansum was again isolated from artificially inoculated tubers to complete Koch's assumption. This is the first report of P. expansum causing tuber rot in A. americana in South Korea. As the cultivated area of Apios is increasing in Korea, it will be necessary to develop effective storage methods and management strategies for the control of storage diseases such as blue mold.

Revealing the mechanism underlying the effects of γ-aminobutyric acid-dioscorin interactions on dioscorin structure and emulsifying properties by molecular dynamic simulations

Many studies have shown that γ-aminobutyric acid (GABA) exhibits various beneficial biological activities, including gut-modulating, neuro-stimulating, and cardio-protecting activities. Naturally, GABA exists in small amounts in yam, which is primarily synthesized by the decarboxylation of L-glutamic acid in the presence of glutamate decarboxylase. Dioscorin, the major tuber storage protein of yam, has been shown to have good solubility and emulsifying activity. However, how GABA interacts with dioscorin and affects their properties has yet to be clarified. In this research, the physicochemical and emulsifying properties of GABA-fortified dioscorin, which was dried by spray drying and freeze drying, were studied. As results, the freeze-dried (FD) dioscorin produced more stable emulsions, while the spray-dried (SD) dioscorin adsorbed more rapidly to oil/water (O/W) interface. The fluorescence spectroscopy, ultraviolet spectroscopy and circular dichroism spectroscopy showed that GABA changed the structure of dioscorin, by exposing its hydrophobic groups. The addition of GABA significantly promoted the adsorption of dioscorin to the O/W interface and prevented droplets coalescence. The results of molecular dynamics simulation (MD) showed that GABA destroyed the H-bond network between dioscorin and water, increased surface hydrophobicity and finally improved the emulsifying properties of dioscorin.

Pre-harvest exogenous application of growth regulators extends storability and maintains the seed potato quality

Preservation of potato tubers is essential not only for their general marketability but also for their potential use as seed potatoes. In subtropical areas, the small and marginal seed potato growers stored their produce at ambient temperature and thus prolonging storability through diverse seed storage techniques. Application of exogenous growth regulators is one the approaches which affect the quality of potato tubers positively. The present study assessed the impact of exogenous growth regulation on the storage and post-harvest quality of potato tubers. The seed potatoes crop was treated with growth regulators at 45 and 60 d after sowing to determine their effect on physiological losses and quality of tubers in storage at ambient temperature during 2019–20 and 2020–21. Application of GA200 reduced the total weight loss by 23.7 and 24.5% during 1st and 2nd year, respectively, compared to the untreated control. Among the auxin treatments, the minimum weight loss was recorded with IBA200. At 120 d of storage, GA200 resulted in a higher tuber dry-matter and total phenol content, compared to the untreated control. IBA200 pre-harvest application led to lower sprouting characteristics, followed by IBA100, NAA50, and NAA25. The Pearson correlation analysis revealed that post-harvest quality was negatively correlated with total weight loss and disease incidence (soft and dry rot). Among all the treatments, Ethrel50 was the more susceptible to soft and dry rot incidence. IBAs exhibited superior efficacy over NAAs in the suppression of storage diseases. In conclusion, a pre-harvest application of GA200 at 45 and 60 d after sowing can prolong the shelf life of seed potatoes at ambient temperature while maintaining or improving their post-harvest quality.

New Report of Oriental Mealybug Rhizoecus Amorphophalli Betrem (Hemiptera: Pseudococcidae) in Amorphophallus Muelleri Tubers in Indonesia

Since 2020 porang (Amorphophallus muelleri Blume) has been declared as an important commercial crop grown in Indonesia. Recently, porang tubers a coated of a distinct white waxy substance was observed at seed storage. The symptoms pose a threat to tuber vigour quality due to the intensive infestation on stored tubers. This sap- sucking insect sucks the juice leading to desiccation and shrivelling of tubers. This study aims to identify the sap- sucking insect pest attacks the storage porang tubers. The studies carried out at ILETRI. Identification of the caused insect species was done by observing symptoms visually, morphological identification of adult females using Compound microscope Olympus Bx43 in 40 X magnification, and tuber germination and growth of 250 infested tubers in the field. Regarding to the specific symptoms whose soft body coated of a distinct white waxy substance and morphological measurement of the average length of the adult females (862.62±46.3 μm with range between 764 - 904 μm), it’s supposed caused by mealybug in Rhizoecus amorphophalli (Hemiptera:Pseudococcidae). Our founding revealed that R. amorphophalli is first discovered as causal agent of a mealybug pest of porang in Indonesia and turned out to be very detrimental because their infestation caused 90 percent of infested porang tubers unable to germinate and grow.

Medicinal effect of carrot and storage technologies in modern refrigerated warehouses

This article shows the importance of the local carrot root fruit in the national economy, which is loved by the population today. Its branches of use for the food industry, i.e. cases of maximum preservation of its medicinal properties and chemical composition compared to other types of vegetables, in the production of various products in a fresh yellow appearance, storage and processing for certain periods, have been studied. In addition, the superiority levels of carrots over other products, as well as the main chemical composition of carrot tubers in any form of use, the amount of dissolved dry matter in the tubers and the level of acidity in the juice were studied. The dependence of the storage period of carrots in the freshly cut state and the long-term storage period, in addition, the main technological parameters in the process of long-term storage of carrot tubers in modern refrigerated warehouses are presented. Information on the total amount of natural weight loss during initial cooling and long-term storage with changes in quality indicators depending on the temperature and relative humidity of the air in the cooling chamber is presented.

A Microcontroller Based Proportional Integral Derivative Controller for Yam Tuber Storage Chamber Temperature and Humidity Control

Adequate and suitable controlled atmosphere plays an important role in post-harvest yam tuber storage environment for sustaining the quality and quantity of yam tuber especially in a reputable country that produces largest quantities of yam in the world. The effect of post-harvest loss is caused due to lack of appropriate storage systems and these had been the most common problem faced by small-holder yam farmers. In order to avoid post-harvest losses and food wastages due to poor atmospheric condition in West Africa, this paper proposed a microcontroller based Proportional Integral Derivative (PID) controller for controlling the temperature and humidity of yam tuber post-harvest storage. The due technique would maintain a relatively constant temperature and humidity in a storage chamber so as to minimized high level of yam postharvest losses that has become a serious economic and food security threat in West Africa. Some mathematical equations were formulated based on temperature and humidity storage chamber models using heat and energy balance principles. The models were designed using Proteus tools and simulated in Simulink form. The parameters of PID controller were tuned with Ziegler Nichols to achieve a desirable steady state response. The system performances were evaluated in settling time, temperature and humidity set point tracking. The performance metrics were compared with existing technique of Fuzzy Logic Controller (FLC). The sensitivity of the results justified that proposed technique gave a better performance in terms of decreased in settling time, temperature and humidity.