Total cyanide content of cassava food products in Australia

An affordable, field-deployable detecting system for cyanide ion - Investigating applications in real time uses

A highly efficient system that incorporates the instantaneous visualization of the cyanide ion in water was synthesized by keeping the fluorophore system (electron donor) as a julolidine-coumarin conjugate and changing the electron acceptor unit. The probes exhibit a notable color change in normal and UV light. The probe interaction modalities are based on the ICT process. With a detection limit in the nM range, it may preferentially react with cyanide, which is less than the tolerable level of 1.9 μM. According to 1H NMR data, the probes detect cyanide ions by nucleophilic addition reaction mechanism. Furthermore, current probe successfully determines real resources, including cyanide containing cassava powder, sprouted potatoes and various water samples. Besides the test strips, an electronic Arduino device was also employed to detect the cyanide ion. As such, the developed probes exhibit outstanding practical application with respect to the cyanide ion.

Evaluation of exposure to cyanogenic glycosides and potential hydrogen cyanide release in commercially available foods among the Korean population

The release of hydrogen cyanide (HCN) after food ingestion can pose a serious health risk to consumers. This study aimed to simultaneously quantify four cyanogenic glycosides (lotaustralin, prunasin, taxiphyllin, and dhurrin) using liquid chromatography-tandem mass spectrometry. The analysis scope extended beyond agricultural products to various consumer foods to estimate dietary exposure to cyanogenic glycosides and assess its risk levels. The major exposure sources are cassava chips (lotaustralin), apples (seeds) (prunasin and dhurrin), and Prunus mume axis (taxiphyllin). In addition to quantifying specific cyanogenic glycosides, this study proposed the development of a preliminary risk assessment framework based on the dietary exposure assessment and the calculation of theoretical levels of HCN derived from cyanogenic glycoside concentrations. In the absence of established guidelines for the permissible intake of foods containing cyanogenic glycosides, this study provides initial guidance for assessing the risks associated with a range of commonly consumed foods.

Cassava

Gleadow et al. introduce the food crop cassava.

CRISPR-Cas9-mediated knockout of CYP79D1 and CYP79D2 in cassava attenuates toxic cyanogen production

Cassava (Manihot esculenta) is a starchy root crop that supports over a billion people in tropical and subtropical regions of the world. This staple, however, produces the neurotoxin cyanide and requires processing for safe consumption. Excessive consumption of insufficiently processed cassava, in combination with protein-poor diets, can have neurodegenerative impacts. This problem is further exacerbated by drought conditions which increase this toxin in the plant. To reduce cyanide levels in cassava, we used CRISPR-mediated mutagenesis to disrupt the cytochrome P450 genes CYP79D1 and CYP79D2 whose protein products catalyze the first step in cyanogenic glucoside biosynthesis. Knockout of both genes eliminated cyanide in leaves and storage roots of cassava accession 60444; the West African, farmer-preferred cultivar TME 419; and the improved variety TMS 91/02324. Although knockout of CYP79D2 alone resulted in significant reduction of cyanide, mutagenesis of CYP79D1 did not, indicating these paralogs have diverged in their function. The congruence of results across accessions indicates that our approach could readily be extended to other preferred or improved cultivars. This work demonstrates cassava genome editing for enhanced food safety and reduced processing burden, against the backdrop of a changing climate.

Ensiling Cyanide Residue and In Vitro Rumen Fermentation of Cassava Root Silage Treated with Cyanide-Utilizing Bacteria and Cellulase

Cyanide is a strong toxin in many tropical forage plants that can negatively affect ruminants. The aim of this study is to determine the cyanide removal efficiency, silage quality, and in vitro rumen fermentation of fresh cassava roots ensiled without an additive (control) and with Acremonium cellulase (AC), two cyanide-utilizing bacterial inoculants (Enterococcus feacium KKU-BF7 (BF7) and E. gallinarum KKU-BC10 (BC10)), and their combinations (BF7 + BC10, AC + BF7, AC + BC10 and AC + BF7 + BC10). A completely randomized design was used with eight treatments × four small-scale silo replicates. Additionally, extra silage samples (seven silos/treatment for individually opening after 0, 1, 3, 5, 7, 15, and 30 days of ensiling) were added to observe the changes in the total cyanide concentration and pH value. The fresh cassava root contained an optimal number of lactic acid bacteria (105 colony forming units/g fresh matter), and the contents of dry matter (DM) and total cyanides were 30.1% and 1304 mg/kg DM, respectively. After 30 days of ensiling, all silages demonstrated a low pH (<3.95; p < 0.01). Cyanide content ranged from 638 to 790 mg/kg DM and was highest in the control (p < 0.01). The addition of BF7 + BC10 increased the crude protein (CP) content (p < 0.01). The addition of AC decreased the fibrous contents (p < 0.01). The control had less acetic acid and propionic acid contents (p < 0.01) and a greater butyric acid content (p < 0.01). However, the degrees of in vitro DM digestibility (IVDMD) and gas production were similar among treatments. Methane production ranged between 29.2 and 33.3 L/kg IVDMD (p < 0.05), which were observed in the AC + BC10 and BF7 + BC10 treatments, respectively. Overall, our results suggested that the cyanide removal efficiency after 30 days of ensiling with good-quality cassava-root silage was approximately 39% of the initial value. The enterococci inoculants and/or AC could improve the ensiling process and cyanide removal efficiency (increasing it to between 47 and 51% of the initial value). The novel enterococci inoculants (BF7 + BC10) were associated with a decreased cyanide content and an increased CP content. They appeared to promote the methanogenesis potential of the cassava root silage. More research is required to validate the use of cyanide-utilizing bacterial inoculants in cyanogenetic plants, bioenergy fermentation, and livestock.

Genetic variation in hydrogen cyanide potential of perennial sorghum evaluated by colorimetry

Both annual and perennial sorghum biomass serve as important forage for ruminant animals around the world. Unfortunately, sorghum can produce hydrogen cyanide (HCN), which, if occurring in high enough concentrations, can be toxic or lethal to animals that consume it. The objectives of this study were to develop a fast and inexpensive colorimetric assay to measure the hydrogen cyanide potential (HCN-P) as well as to compare this with existing visual assays while assessing the range of variation for HCN-P among perennial and annual sorghum biomass. The HCN-P of 100 sorghum lines derived from an interspecific hybridization program was determined over 2 years (establishment and regrowth) using both visual and colorimetric assays. Visual assessment underestimated the HCN-P and was less accurate than colorimetry. Repeatability for HCN-P across all sampling dates was functionally zero in the visual assessment and low for the colorimetric assay. This was mostly explained by the significant pedigree × year interaction effects and growth stage. Growth stage substantially influenced HCN-P, which should be considered when feeding animals on fresh forage.

A fully water-soluble Calix[4]arene probe for fluorometric and colorimetric detection of toxic hydrosulfide and cyanide ions: Practicability in living cells and food samples

Although hydrosulfide and cyanide anions play important roles in daily life that they are available in a lot of foods. However, their excess amounts contaminate water, land, and food and cause serious problems to human health. Herein, we introduce a water-soluble macrocyclic sensor based-on Calix[4]arene (MPI-Calix[4]) with dual response sites for fluorescence recognizing cyanide (CN^-) and hydrogen sulfide (HS^-) under longwave light. MPI-Calix[4] exhibits a high selectivity and sensitivity in the detection of CN^- and HS^-, where the limits of detection were as low as 0.115 and 8.12 μmol/L, respectively. The cell imaging studies shows that this probe can be easily used in the detection of CN^- and HS^- on living cells. Full understanding of these results paved a fruitful system to improve an applicable analytical process for food safety and quality.

Cyanide Content of Cassava Food Products Available in Australia

In 2009, Food Standards Australia New Zealand set a total cyanide content limit of 10 ppm for ready-to-eat cassava products to address food safety concerns about cyanogenic glucosides in cassava. This study surveys a range of cassava food products available in Melbourne, Australia, ten years after the implementation of these regulations. Of all the products tested, the mean cyanide content was greatest in ready-to-eat cassava chips (48.4 ppm), although imported ready-to-eat products had a higher mean cyanide content (95.9 ppm) than those manufactured in Australia (1.0 ppm). Cyanide was detected in frozen cassava products (grated mean = 12.9 ppm; whole root mean = 19.8 ppm), but was significantly reduced through processing according to packet instructions in both product types. Three methods were used to quantify total cyanide content: the evolved cyanide method, the picrate absorbance method and the picrate chart method, with satisfactory agreement between methods. The picrate absorbance and chart methods reported mean cyanide contents 13.7 ppm and 23.1 ppm higher, respectively, than the evolved cyanide method. Our results reaffirm the need for the ongoing testing of cassava food products, especially ready-to-eat products whose cyanide content will not be reduced before consumption.

Biochemical Analysis of Cassava (Manihot esculenta Crantz) Accessions in Southwest of Ethiopia

Cassava is a significant contributor to food security and an income source for smallholder farmers in southern Ethiopia. However, little research effort has been done so far based on designing field experiment samples for the biochemical composition of cassava accession at the country level. The study was conducted to assess the biochemical composition of cassava accessions in southwest Ethiopia. Flour samples from the storage roots of 64 cassava accessions were collected and were run in duplicates. Data on 13 biochemical characters were collected and analyzed using standard methods. The analysis of variance showed significant to very highly significant differences among the tested accessions for biochemical composition. The flour moisture ranged from 4.83–10.11%, dry matter (89.89-95.17%), organic matter (86.71–92.65%), ash (2.1–3.96%), fiber (1.14–3.00%), fat (0.26-1.4%), crude protein (1.28-2.86%), starch (65.1–74.2%), carbohydrate (81.29–87.94%), energy (341.44–367.61 kcal/100g DM), and cyanide (1.67–3.14). The highest GCV = 29.54% was shown for crude fat, followed by GCV = 16.94% for crude fiber, and GCV = 16.11% for tannin, whereas, among the characters, dry matter was observed to be the lowest (GCV = 0.84%). The GAM ranged from protein 0.30% to 54.94% for fat, while heritability ranged from flour moisture and dry matter (17.29%) to 84.88% for cyanide. The first five principal components explained 80.1% of the total variation, with PC I accounting for 37%, PC II 15.4%, PC III 11.6%, PC IV 8.4%, and PC V 8.20% of the total variation. This study found the presence of high biochemical variability among the tested accessions’ roots and could be used to select accessions with desirable biochemical composition in future breeding work.

Naked-eye colorimetric and turn-on fluorescent Schiff base sensor for cyanide and aluminum (III) detection in food samples and cell imaging applications

A new efficient Schiff base sensor SB3 for fluorescent and colorimetric "naked-eye" "turn-on" sensing of cyanide anion (CN^-) with excellent sensitivity and selectivity was developed. The 4,4'-(perfluoropropane-2,2-diyl)bisphenol group and two phenyl groups were covalently linked by two C = N bonds to extend the conjugation length. The four hydroxyl groups can improve the water solubility of the SB3 sensor. The SB3 sensor exhibited high specificity towards CN^- by interrupting its intramolecular charge transfer, resulting in a color change and remarkable "turn-on" green fluorescence emission. The sensing mechanism is caused by the nucleophilic addition of CN- toward imine groups of the SB3 sensor, leading to breaks of the conjugation, fluorescent spectral changes, and color change. It was confirmed by ¹H NMR titration and Mass spectra. The detection limits for CN^- and Al³⁺obtained by fluorescence spectrum are 0.80 µM and 0.25 µM, respectively. The SB3 sensor can act as an efficient chemical sensor for detecting the CN^- and Al³⁺ ions under common environmental and physiological conditions (pH 5-12). Besides, the sensor can also detect CN^- in food materials (such as sprouting potatoes and cassava flour) and imaging CN^-in living cells with strong "turn-on" fluorescence at 490 nm. SB3 is an excellent CN^- sensor that exhibits some advantages, including easy synthesis, distinct fluorescence and color change, high selectivity, low detection limit, and good anti-interference ability to analyze solution and food samples, together with fluorescence cell imaging.

Process-Induced Modifications on Quality Attributes of Cassava (Manihot esculenta Crantz) Flour

Cassava flour (CF) is a suitable representative and one of the easiest shelf-stable food products of the edible portion of the highly perishable cassava root (Manihot esculenta Crantz). The quality and type of CF are dependent on processing variables. Broadly categorized into fermented and unfermented CF, unfermented CF is white, odorless, and bland, while fermented CF has a sour flavor accompanied by its characteristic odor. The use of fermented CF as a composite is limited because of their off-odors. Modifications in CF processing have given rise to prefixes such as: modified, unmodified, gelatinized, fortified, native, roasted, malted, wet, and dry. Consumed alone, mostly in reconstituted dough form with soups, CF may also serve as a composite in the processing of various flour-based food products. Fermenting with microorganisms such as Rhizopus oryzae and Saccharomyces cerevisiae results in a significant increase in the protein content and a decrease in the cyanide content of CF. However, there are concerns regarding its safety for consumption. Pre-gelatinized CF has potential for the textural and structural improvement of bakery products. The average particle size of the CF also influences its functional properties and, subsequently, the quality of its products. Cassava flour is best stored at ambient temperature. Standardizing the processing of CF is a challenge because it is mostly processed in artisanal units. Furthermore, each variety of the root best suits a particular application. Therefore, understanding the influence of processing variables on the characteristics of CF may improve the utilization of CF locally and globally.

Amygdalin: Toxicity, Anticancer Activity and Analytical Procedures for Its Determination in Plant Seeds

Amygdalin (d-Mandelonitrile 6-O-β-d-glucosido-β-d-glucoside) is a natural cyanogenic glycoside occurring in the seeds of some edible plants, such as bitter almonds and peaches. It is a medically interesting but controversial compound as it has anticancer activity on one hand and can be toxic via enzymatic degradation and production of hydrogen cyanide on the other hand. Despite numerous contributions on cancer cell lines, the clinical evidence for the anticancer activity of amygdalin is not fully confirmed. Moreover, high dose exposures to amygdalin can produce cyanide toxicity. The aim of this review is to present the current state of knowledge on the sources, toxicity and anticancer properties of amygdalin, and analytical methods for its determination in plant seeds.

Cyanogenic Glycoside Analysis in American Elderberry

Cyanogenic glycosides (CNGs) are naturally occurring plant molecules (nitrogenous plant secondary metabolites) which consist of an aglycone and a sugar moiety. Hydrogen cyanide (HCN) is released from these compounds following enzymatic hydrolysis causing potential toxicity issues. The presence of CNGs in American elderberry (AE) fruit, Sambucus nigra (subsp. canadensis), is uncertain. A sensitive, reproducible and robust LC-MS/MS method was developed and optimized for accurate identification and quantification of the intact glycoside. A complimentary picrate paper test method was modified to determine the total cyanogenic potential (TCP). TCP analysis was performed using a camera-phone and UV-Vis spectrophotometry. A method validation was conducted and the developed methods were successfully applied to the assessment of TCP and quantification of intact CNGs in different tissues of AE samples. Results showed no quantifiable trace of CNGs in commercial AE juice. Levels of CNGs found in various fruit tissues of AE cultivars studied ranged from between 0.12 and 6.38 µg/g. In pressed juice samples, the concentration range measured was 0.29-2.36 µg/mL and in seeds the levels were 0.12-2.38 µg/g. TCP was highest in the stems and green berries. Concentration levels in all tissues were generally low and at a level that poses no threat to consumers of fresh and processed AE products.

Triple Action Sensing Behaviour of a Single Receptor for the Detection of Multiple Analytes via Different Approaches

The thiosemicarbazide based receptor was synthesized with 4-(diethylamino)salicylaldehyde and N- phenyl-thiosemicarbazide by the simple condensation method and the properties were studied under the naked eye, UV-Vis and fluorescence studies etc. The synthesized receptor detects cyanide, cobalt, and mercury in acetonitrile medium. The observed color changes included colourless to yellow for cyanide, colourless to green for cobalt and colourless to yellow for mercury which were seen under naked eye without the aid of any instruments. Furthermore, the cyanide bound receptor detects Cr³⁺ by the relay recognition method. The detection limit of receptor with cyanide, cobalt & mercury was found to be 5.8 × 10^- 7 M, 3.6 × 10^- 7 M and 8.1 × 10^- 7 M respectively. Experimental results were verified by DFT calculations. Receptor was successfully employed in the construction of INHIBIT and IMPLICATION logic gates.

Quantification of amygdalin, prunasin, total cyanide and free cyanide in powdered loquat seeds

Amygdalin, prunasin, total cyanide and free cyanide concentrations in 12 powdered loquat seeds were investigated. Loquat (Eriobotrya japonica) is a species of flowering plant in the family Rosaceae, and its fruit is quite popular in Japan. Amygdalin and prunasin were measured using LC-MS/MS. Total cyanide was measured by enzymatic treatment, steam distillation and colorimetric quantification using the pyridine-pyrazolone method. Free cyanide was measured without enzymatic treatment. The mean concentrations of amygdalin, prunasin, total cyanide and free cyanide in powdered loquat seeds were 5900, 760, 410 and 44 mg/kg, respectively. The range of each quantitative value was extensive. Seven out of twelve samples were at risk for exceeding the acute reference dose (ARfD) of cyanide.

Cassava consumption and the occurrence of cyanide in cassava in Vietnam, Indonesia and Philippines

OBJECTIVE

To make a tentative assessment of the consumption of cassava in three countries in South-east Asia and the cyanogenic potential (CNp) of the crop as a possible food safety issue.

DESIGN

We used data from the Ministry of Health in Vietnam and Statistics Authorities in Indonesia and Philippines (mean household consumption per province) to assess cassava consumption. Conversions of units were needed to facilitate the comparison of cassava consumption between countries. The most up-to-date data available regarding both cassava consumption and the CNp of cassava grown in the respective countries were assessed.

SETTINGS

Vietnam, Indonesia and Philippines.

PARTICIPANTS

Respondents from provinces in Vietnam (nineteen), Indonesia (thirty-three) and Philippines (eighty-one) were asked to complete a recall questionnaire detailing either the previous 24-h' or the 7-d' cassava consumption.

RESULTS

Among the three countries, available data indicated that the highest median cassava-consumption figures percapita were from Indonesia and the Philippines (9·01 and 7·28 g/capita per d, respectively), with Vietnam having the least (1·14 g/capita per d). Published information regarding the CNp of cassava in the three countries was limited.

CONCLUSIONS

While the findings of the present study are somewhat limited by a lack of available information regarding both the extent of cassava consumption and the CNp of cassava consumed in the three countries, it appears likely that cyanogen intake arising from cassava consumption among the three countries exceeds the FAO/WHO Provisional Maximum Tolerable Daily Intake, although any risk to public health appears limited to a minority of provinces in each country.

Smartphone coupled with a paper-based optode: Towards a selective cyanide detection

A low-cost on-paper sensor based on 5,10,15-tritolylcorrolatocobalt(III) triphenylphosphine, CoTTCorr(PPh3), was developed for cyanide detection in aqueous solutions. The sensor was coupled to a smartphone and used a home-written color intensity analysis software in order to record and interpret the colorimetric response. The detection of cyanide was possible down to 0.053 mg/L, an order of magnitude lower than the value of 0.5 mg/L set by the World Health Organization (WHO) for safe short-term exposure of cyanide in potable water. The colorimetric sensor had selectivity toward cyanide ions over the anions Cl-, Br, F-, NO2, SCN-, OA[Formula: see text]-,ClO4-, H2PO4- and HCO3- while the influence of NO3- ions on the sensor optical response towards cyanide was overcome by optimization of the ionophore/anion-exchanger ratio inside the sensing material. The best performance was obtained for the optode with an ionophore to exchanger ratio of 1:3. The optimized optodes were employed for quantification of cyanide content added to potable water and saliva.

A computer-based approach for developing linamarase inhibitory agents

Cassava is a strategic crop, especially for developing countries. However, the presence of cyanogenic compounds in cassava products limits the proper nutrients utilization. Due to the poor availability of structure discovery and elucidation in the Protein Data Bank is limiting the full understanding of the enzyme, how to inhibit it and applications in different fields. There is a need to solve the three-dimensional structure (3-D) of linamarase from cassava. The structural elucidation will allow the development of a competitive inhibitor and various industrial applications of the enzyme. The goal of this review is to summarize and present the available 3-D modeling structure of linamarase enzyme using different computational strategies. This approach could help in determining the structure of linamarase and later guide the structure elucidationin silicoand experimentally.

Dual mode detection of CN- & Cu2+ using fluorene moiety with logic gate, DFT studies and real sample analysis applications

A simple colorimetric receptor was synthesized by the condensation of 2-amino fluorene with 2-hydroxy-5-nitrobenzaldehyde and its properties were investigated using colorimetric, fluorescence and DFT studies. The sensing mechanism was ascertained by ¹H NMR titration studies. The synthesized receptor showed two-pronged chemosensing properties and exhibited remarkable colorimetric transitions from colorless to yellow in the presence of CN^- and colorless to green in the presence of Cu²⁺ in 80:20 acetonitrile/water medium, which could be determined by naked eye observations. The detection limit of receptor to CN^- and Cu²⁺ ion was found to be 7.9 × 10^-7 M and 4.5 × 10^-8 M respectively. Receptor was also successfully employed in the construction of molecular INHIBIT and YES logic gates. The synthesized receptor was also efficiently used for real-sample analysis in Finger Millet, also known as Ragi in Tamil. Its scientific name is Eleusine coracana.

Evaluation of the health risks related to the presence of cyanogenic glycosides in foods other than raw apricot kernels

In 2016, the EFSA Panel on Contaminants in the Food Chain (CONTAM) published a scientific opinion on the acute health risks related to the presence of cyanogenic glycosides (CNGs) in raw apricot kernels in which an acute reference dose (ARfD) of 20 μg/kg body weight (bw) was established for cyanide (CN). In the present opinion, the CONTAM Panel concluded that this ARfD is applicable for acute effects of CN regardless the dietary source. To account for differences in cyanide bioavailability after ingestion of certain food items, specific factors were used. Estimated mean acute dietary exposures to cyanide from foods containing CNGs did not exceed the ARfD in any age group. At the 95th percentile, the ARfD was exceeded up to about 2.5-fold in some surveys for children and adolescent age groups. The main contributors to exposures were biscuits, juice or nectar and pastries and cakes that could potentially contain CNGs. Taking into account the conservatism in the exposure assessment and in derivation of the ARfD, it is unlikely that this estimated exceedance would result in adverse effects. The limited data from animal and human studies do not allow the derivation of a chronic health-based guidance value (HBGV) for cyanide, and thus, chronic risks could not be assessed.

Efficiency of Cassava Production in China: Empirical Analysis of Field Surveys from Six Provinces

Cassava is becoming increasingly important as an industrial raw material in China. However, an insufficient supply of cassava raw materials and the expanding demand for cassava in downstream-processing industries restricts the development of the cassava industry in China. This paper studies how to increase the scale of cassava planting and promoting cassava production efficiency using output-oriented Data Envelopment Analysis (DEA) modeling. Overall Technical Efficiency (OTE), Pure Technical Efficiency (PTE), and Scale Efficiencies (SE) of the cassava-production system in the major cassava production areas of China are calculated using Variable Returns to Scale (VRS). Results reveal that, in addition to the Guangdong province, the OTE of Guangxi, Hainan, Fujian, Yunnan, and Jiangxi is inefficient, with an OTE of less than 1. The largest cassava-planting province, Guangxi, has the lowest SE with 0.551. The PTE of Guangxi is close to the minimum with 0.344. The OTE of Guangxi is also the lowest among the five provinces with 0.190. This study also presents ways to improve production efficiency. Results reveal that Guangxi has a large ratio of transverse adjustment on average. In the Guangxi province, 1.70% of the service cost and 1.72% of the labor cost need to be eliminated to keep the current output scale. Meanwhile, service and labor costs need to be reduced by 3164.85 and 3209.92, respectively, to achieve the best production efficiency. Further industrialization and large-scale cassava cultivation, increased yield, and strengthened cooperation with the Association of South East Asian Nations (ASEAN) and Africa are suggested as policy options to improve the cassava system in China.

A socio-scientific analysis of the environmental and health benefits as well as potential risks of cassava production and consumption

Due to its high adaptability, cassava (Manihot esculenta Crantz) is one of the world's most cultivated and consumed plants after maize and rice. However, there are relatively few scientific studies on this important crop. The objective of this review was therefore to summarize and discuss the available information on cassava cropping in order to promote sustainable practices in terms of production and consumption. Cassava cultivation has been expanding recently at the global scale and is widely consumed in most regions of South America, Africa, and Asia. However, it is also characterized by the presence in its roots of potentially toxic hydrocyanic acid. Furthermore, cassava can also absorb pollutants as it is currently cultivated near roads or factories and generally without consideration for potential sources of soil, water, or atmospheric pollution. Careful washing, peeling, and adequate preparation before eating are therefore crucial steps for reducing human exposure to both environmental pollutants and natural hydrocyanic acid. At present, there is not enough precise data available on this staple food crop. To improve our knowledge on the nutritive benefits versus health risks associated with cassava consumption, further research is necessary to compare cassava cultivars and precisely study the influence of preparation methods.

Interactive effects of temperature and drought on cassava growth and toxicity: implications for food security?

Cassava is an important dietary component for over 1 billion people, and its ability to yield under drought has led to it being promoted as an important crop for food security under climate change. Despite its known photosynthetic plasticity in response to temperature, little is known about how temperature affects plant toxicity or about interactions between temperature and drought, which is important because cassava tissues contain high levels of toxic cyanogenic glucosides, a major health and food safety concern. In a controlled glasshouse experiment, plants were grown at 2 daytime temperatures (23 °C and 34 °C), and either well-watered or subject to a 1 month drought prior to harvest at 6 months. The objective was to determine the separate and interactive effects of temperature and drought on growth and toxicity. Both temperature and drought affected cassava physiology and chemistry. While temperature alone drove differences in plant height and above-ground biomass, drought and temperature × drought interactions most affected tuber yield, as well as foliar and tuber chemistry, including C : N, nitrogen and cyanide potential (CNp; total cyanide released from cyanogenic glucosides). Conditions that most stimulated growth and yield (well-watered × high temperature) effected a reduction in tuber toxicity, whereas drought inhibited growth and yield, and was associated with increased foliar and tuber toxicity. The magnitude of drought effects on tuber yield and toxicity were greater at high temperature; thus, increases in tuber CNp were not merely a consequence of reduced tuber biomass. Findings confirm that cassava is adaptable to forecast temperature increases, particularly in areas of adequate or increasing rainfall; however, in regions forecast for increased incidence of drought, the effects of drought on both food quality (tuber toxicity) and yield are a greater threat to future food security and indicate an increasing necessity for processing of cassava to reduce toxicity.

Spectrometric and kinetics studies involving anionic chromogenic chemodosimeters based on silylated imines in acetonitrile or acetonitrile–water mixtures

The nucleophilic attack of F⁻ or CN⁻ on the silicon center of chemodosimeters, through an S_N2@Si mechanism, released colored phenolates as leaving groups. NMR, PGSE NMR, and UV-vis studies provided evidence on the mechanism of the reactions.

Rapid measurement of free cyanide in liquor by ion chromatography with pulsed amperometric detection

This study investigated the measurement of free cyanide in liquor by ion chromatography coupled with pulsed amperometric detection (IC-PAD). Eluent concentration, interferent evaluation and method performance were discussed. Results show that free cyanide in liquor can be rapidly determined by the optimised IC-PAD method. A sample requires only 1:100 dilution and simple filtration before being subjected to IC-PAD. The linear range is 1-5000 μg/L with an R value of 0.9998. The detection limit is 1 μg/L for a 25 μL injection loop. The overall relative standard deviation (RSD) of the method is less than 5%, and the recovery range is from 98.1% to 105.0%. This study has been proven significant and may have potential applications in liquors analysis.

Straightforward rapid spectrophotometric quantification of total cyanogenic glycosides in fresh and processed cassava products

In this study, we extend pioneering studies and demonstrate straightforward applicability of the corrin-based chemosensor, aquacyanocobyrinic acid (ACCA), for the instantaneous detection and rapid quantification of endogenous cyanide in fresh and processed cassava roots. Hydrolytically liberated endogenous cyanide from cyanogenic glycosides (CNp) reacts with ACCA to form dicyanocobyrinic acid (DCCA), accompanied by a change of colour from orange to violet. The method was successfully tested on various cassava samples containing between 6 and 200 mg equiv. HCN/kg as verified with isonicotinate/1,3-dimethylbarbiturate as an independent method. The affinity of ACCA sensor to cyanide is high, coordination occurs fast and the colorimetric response can therefore be instantaneously monitored with spectrophotometric methods. Direct applications of the sensor without need of extensive and laborious extraction processes are demonstrated in water-extracted samples, in acid-extracted samples, and directly on juice drops. ACCA showed high precision with a standard deviation (STDV) between 0.03 and 0.06 and high accuracy (93-96%). Overall, the ACCA procedure is straightforward, safe and easily performed. In a proof-of-concept study, rapid screening of ten samples within 20 min has been tested.

Potential Toxic Levels of Cyanide in Almonds (Prunus amygdalus), Apricot Kernels (Prunus armeniaca), and Almond Syrup

Under normal environmental conditions, many plants synthesize cyanogenic glycosides, which are able to release hydrogen cyanide upon hydrolysis. Each year, there are frequent livestock and occasional human victims of cyanogenic plants consumption. The present work aims to determine the hydrocyanic acid content in different samples of cyanogenic plants, selected from the Tunisian flora, and in the almond syrup. In order to evaluate their toxicity and their impact on the consumer health in the short term as well as in the long term, using the ISO 2164-1975 NT standard, relating to the determination of cyanogenic heterosides in leguminous plants.

Cyanogenic glycosides in plant-based foods available in New Zealand

Cyanogenic glycosides occur in a wide range of plant species. The potential toxicity of cyanogenic glycosides arises from enzymatic degradation to produce hydrogen cyanide, which may result in acute cyanide poisoning and has also been implicated in the aetiology of several chronic diseases. One hundred retail foods were sampled and analysed for the presence of total hydrocyanic acid using an acid hydrolysis-isonicotinic/barbituric acid colourimetric method. Food samples included cassava, bamboo shoots, almonds and almond products, pome fruit products, flaxseed/linseed, stone fruit products, lima beans, and various seeds and miscellaneous products, including taro leaves, passion fruit, spinach and canned stuffed vine leaves. The concentrations of total hydrocyanic acid (the hydrocyanic acid equivalents of all cyanogenic compounds) found were consistent with or lower than concentrations reported in the scientific literature. Linseed/flaxseed contained the highest concentrations of total hydrocyanic acid of any of the analysed foods (91-178 mg kg(-1)). Linseed-containing breads were found to contain total hydrocyanic acid at concentrations expected from their linseed content, indicating little impact of processing on the total hydrocyanic acid content. Simulation modelling was used to assess the risk due to the total hydrocyanic acid in fruit juice and linseed-containing bread. 

A modified ninhydrin micro-assay for determination of total cyanogens in plants

Indirect quantification of total cyanogenic compounds (cyanogens) in plants was studied using a novel ninhydrin-based spectrophotometric micromethod. The ninhydrin-cyanide system obeys Beer's law in the range from 20 μg L(-1) to 800 μg L(-1) CN(-) with molar absorptivity ε=1.4×10(5) L mol(-1)cm(-1). Recovery at 100 μg L(-1) CN(-) was 100.5±0.1% and LOD and LOQ were 8 and 22 μg L(-1), respectively. The conditions for ninhydrin reagent preparation were discussed. The extraction and separation solutions, extraction and incubation time, and solvent volume were also investigated for maximum recovery of total cyanogens. 0.1% NaHCO3 was used as an extraction solvent for cyanide formed after enzymatic hydrolysis of cyanogens. The procedure was suitable for samples containing more than 90 mg CN(-)/100 g sample. When cyanogen concentrations were lower, the resulted cyanide was separated by microdiffusion in a Conway cell. Water was used as a hydrolysis medium and a donor solvent, while 2% Na2CO3 as an absorbing solution. Total cyanogen content in plum and almond kernels, as well as apple and flax seeds was determined.

Drying and processing protocols affect the quantification of cyanogenic glucosides in forage sorghum

BACKGROUND

Cyanogenic glucosides are common bioactive products that break down to release toxic hydrogen cyanide (HCN) when combined with specific β-glucosidases. In forage sorghum, high concentrations of the cyanogenic glucoside dhurrin lead to reduced productivity and sometimes death of grazing animals, especially in times of drought, when the dhurrin content of stunted crops is often higher. The aim of this study was to develop harvesting protocols suitable for sampling in remote areas.

RESULTS

Dhurrin concentration in air- and oven-dried leaves was the same as in fresh leaves, with no subsequent losses during storage. Dhurrin concentration was halved when leaves were freeze-dried, although activity of the endogenous dhurrinase was preserved. Direct measurement of dhurrin concentration in methanolic extracts using liquid chromatography/mass spectrometry (LC/MS) gave similar results to methods that captured evolved cyanide. A single freezing event was as effective as fine grinding in facilitating complete conversion of dhurrin to cyanide.

CONCLUSION

Direct measurement of dhurrin using LC/MS is accurate but expensive and not appropriate for fieldwork. Air drying provides an accurate, low-cost method for preparing tissue for dhurrin analysis, so long as the specific β-glucosidase is added. It is recommended that comparative studies like the one presented here be extended to other cyanogenic species.

Variations in the chemical composition of cassava ( Manihot esculenta Crantz) leaves and roots as affected by genotypic and environmental variation

The purpose of this study was to assess the quality of cassava cultivars, in terms of cyanogenic potential and composition of macro- and micronutrients, sampled from different locations in rural Mozambique. Total cyanide concentrations in fresh cassava tissues were measured using portable cyanide testing kits, and elemental nutrients were later analyzed from dried plant tissue. Variation in cyanogenic potential and nutrient composition occurred both among cultivars and across locations. The majority of cultivars contained >100 ppm total cyanide, fresh weight, and are therefore considered to be dangerously poisonous unless adequately processed before consumption. Leaf cyanogenic and nutrient content varied with plant water status, estimated using carbon isotope discrimination (δ(13)C). The colonization of roots of all cultivars by arbuscular mycorrhizal fungi was also quantified and found to be high, indicating that mycorrhizas could play a key role in plant nutrient acquisition in these low-input farming systems.