Yam Chips Research Articles

Study of the proximate and mineral composition of different Nigerian yam chips, flakes and flours.

Yam (Dioscorea spp) is an essential tuber crop for hundreds of millions of people in many African, Asian and South American countries. Considering in particular Southwest Nigeria, chips, flakes and flours are amongst the most common shelf-stable traditionally-processed yam products. This paper reports a systematic study on the proximate (moisture, protein, carbohydrate, fibre, fat, ash and gross energy) and mineral composition of these three food commodities sold in Nigerian markets. Results showed no significant differences in the moisture, crude protein and fibre content of all samples (10.0-12.3, 2.7-4.3 and 1.3-2.0wt%, respectively). Gross energy was also comparable for all yam derived food items (between 3300 and 3507kcal/kg), contradicting the common belief that yam flakes have lower nutritional value than chips and flours. Considering the mineral composition, Ca, Mg, P and K were the predominant macronutrients. Micronutrients such as Zn, Co, Mn and Cu were also detected. Significant differences existed between products, and their various sources (markets). Principal component analysis showed a direct correlation between ash content of the samples and the assessed macronutrients, irrespective of the market, or the seller of the commodities. This study confirmed that yam derived food stuffs have an adequate nutritional composition, irrespective of their form and/or origin.

Development and performance evaluation of an effective dryer for poundo yam flour processing plant

AbstractThe process of making pounded yam, from yam, Dioscorea spp., which is mostly consumed by people of sub-Sahara region as source of carbohydrate is energy consuming, therefore, the pounded yam flour, commonly called poundo yam, through which pounded yam is prepared faster and easier, has become popular in West Africa. Although there is an existing niche market for the design and production of poundo yam processing plant, proper drying, one of the most important stages in the production line of poundo yam flour is drying to remove moisture from parboiled (a stage before drying) yam chips still remains the limitation to an effective application of the processing plant in the food industry. The development and performance evaluation of an effective drier that will allow the movement of the dried yam chips to the next machine in poundo yam process plant and its suitability to the food industrial applications was carried out in this research. The volume of the drying drum was estimated to be 0.03 m3. The...

Repellent Effect and Insecticidal Activities ofBridelia ferruginea,Blighia sapida, andKhaya senegalensisLeaves Powders and Extracts againstDinoderus porcellusin Infested Dried Yam Chips

Dinoderus porcellusis considered as the most important pest of stored yam chips and compounds extracted from plants can be used for its control. The present study aimed to test the insecticidal and repellent activities of powders and extracts of leaves ofBridelia ferruginea,Blighia sapida, andKhaya senegalensisagainstD. porcellus. The efficacy of plant powders was compared with the synthetic pesticide Antouka (Permethrin 3 g/kg + pirimiphos 16 g/kg). The results of the experiment revealed that all plant powders were effective as repellents. Antouka was more effective as insecticidal than the plant powders and minimal weight loss was observed withB. sapidaat 2%. Among treatments, propanol extract ofK. senegalensisat 5% was found to elicit the highest repellent effect onD. porcellus. The LC50results revealed that the acetone extract ofK. senegalensisis the most toxic (0.29 μL/insect) to the pest, while the propanol extract ofB. ferrugineaat 5% exhibited strong fumigant toxicity againstD. porcellus, with 88.89% of pest mortality at 160 μL/L air. The findings from the current work proved that plant powders and extracts of the three plants are sources of botanical insecticides which may be used in the integrated management ofD. porcellus.

Functional Response of the Predators Alloeocranum biannulipes (Hemiptera: Reduviidae) and Teretrius nigrescens (Coleoptera: Histeridae) Feeding on Dinoderus porcellus (Coleoptera: Bostrichidae) Infesting Yam Chips.

The functional response and some predation parameters of the predators Alloeocranum biannulipes Montrouzier & Signoret (Hemiptera: Reduviidea) and Teretrius nigrescens Lewis (Coleoptera: Histeridae) were evaluated at five different densities of larvae and pupae of Dinoderus porcellus Lesne (Coleoptera: Bostrichidae) with the aim to understand their roles in the biological control of this major pest of stored yam chips. Experiments were performed in petri dishes at 25 ± 1 °C, 60 ± 10% RH, and a photoperiod of 12:12 (L:D) h in a controlled temperature room. Both predators showed Type II of functional response with respect to larvae, determined by a logistic regression model. However, T. nigrescens significantly killed more larvae of D. porcellus compared with A. biannulipes. This behavior, however, changed to a linear functional response (Type I), when pupae of D. porcellus were offered to both predators, possibly because of their immobility. In addition, there was no significant difference between T. nigrescens and A. biannulipes in terms of the killed pupae. Parameters of the Holling disc equation for both predators were estimated. Estimated handling time on larvae of D. porcellus for T. nigrescens and A. biannulipes was 0.254 and 0.677 h and the rate of searching efficiency was 0.289 and 0.348 h-1, respectively. Results indicated that T. nigrescens was a more suitable candidate for augmentative release for D. porcellus control than A. biannulipes. However, semifield studies are required to draw firm conclusions.

Drying characteristics of Chinese Yam (Dioscorea opposita Thunb.) by far-infrared radiation and heat pump

Chinese Yam chips were dried using a heat pump (HP) dryer alone or in combination with far infrared radiation (FIR) at 500, 1000 and 2000W (500 FIR, 1000 FIR, and 2000 FIR, respectively). The experimental results were presented in terms of the drying characteristics, and dried product qualities (shrinkage, color, texture, percentage of rehydration, and moisture content). Samples with initial moisture content of approximately 76% (w.b.) were dried to a final moisture content of <17% (w.b.) at the drying temperature of 50°C and at an air flow rate of 1.0ms−1 for all of the experiments. The data showed that FIR+HP drying increased the drying rate by reducing the drying time, and the resulted dried Chinese Yam chips generally had higher values of lightness and comparable values of redness and yellowness than the HP-treated samples. In the case of HP+1000FIR, the dried Chinese Yam chips had lower shrinkage, improved rehydration ability, lower hardness and higher brittleness than those dried by HP, HP+500FIR and HP+2000FIR. It is worth noting that the total energy used for FIR-assisted drying processes decreased with the increase of FIR intensity. The present data suggest that HP+FIR drying is an effective and economical method for Chinese Yam chip drying, and HP+1000FIR can obtain the best dried product.

Polyphenol Oxidase Activity and Inhibition in White Yam (Dioscorea Rotundata. Var. Laasirin) Chips as African Fries for Human Consumption

T activity of polyphenol oxidase (PPO) in Dioscorea rotundata var. Laasirin and the adequacy of heat and chemical treatment in inhibiting this enzyme were investigated in this study. PPO was inhibited by hot water blanching at 95oC for 7 minutes and coded as BOX. Chemical treatment using 0.1% Food grade sodium meta-bisulphite was also carried out and coded as XOX while a combination of both the physical method involving heat treatment and chemical methods was used and coded as BXX. The activity of polyphenol oxidase was determined using spectrophotometric method. A significant difference was evidenced in polyphenol oxidase activity amongst the various inhibition methods. The BXX method showed the highest level of inhibition followed by the BOX method and the XOX method. The yam chips produced using the BXX method can therefore be adopted for its commercial production by different categories of food processors for industrial utilization of white yam.

Application of starch-albumen powder as breading material in fried foods: An optimization study

ABSTRACTThe potential of using starch-albumen powder (SAP) as solid coating powder for fried food application was studied. Egg albumen was mixed with 10–30% dried starch and dried at 40–60°C air velocity of 4.5 m/s to produce SAP. SAP was used to coat wet yam chips prior to frying at 180°C for 3 min. The drying temperature and starch content in SAP significantly affected the oil uptake and moisture of fried chips. The increased amount of albumen (or reduced starch) content significantly reduced oil uptake. The sensory attributes influenced the overall acceptability of the fried chips in the order of taste > flavor > texture > appearance. To minimize oil uptake and moisture content and maximize acceptability of the fried chips, SAP dried at temperature of 40°C with starch content of 11.3% should be used. The study further indicates the potential of using SAP as coating in some other food products.

Assessment of Selected Food Products for Pesticide Residue in Major Markets of Oyo State, Nigeria

A study was carried out on the assessment of selected food produce for pesticide residue in Oyo State. With the aid of multi stage sampling technique, 8 selected markets were surveyed in the major constituencies of Oyo State which included Oje and Bodija Market in Ibadan, Arada and Sabo Markets in Ogbomoso, Ajegunle and Araromi Market in Oyo, Owode and Sango Markets in Igboho and Saki respectively in Oke-Ogun. Information on type of pesticide use, reason for choosing the pesticide, method of applying the pesticide and duration of post application storage, were collected. Food produce sampled were yam chips, cowpea, maize and smoked fish for residual analysis. The residual analysis includes extraction of samples, cleaning of extraction and screening of the pesticide using GC-MS to detect any chemical metabolites. The survey reveals that majority (87.5%) of respondents were involved in selling of maize, yam chips and cowpea and the most used pesticide in the market was Aluminium phosphide marketed as phostoxin. Many of respondents applied pesticide by fumigation and the choice of these pesticides was base on customary practices. These food produce are stored for less than a month before being disposed of to consumers. Result from residual analysis shows sample from all the markets contains high percentage of alkane compounds especially the heptadecanes, eicosane, hexadecane and octadecane. Organochlorines were also found in the samples at high percentage. Banned pesticides are still in use in the visited markets and the use of banned pesticide should be prohibited and extension scheme on the use of pesticide on stored produce should be sponsored by government. This will help educate pesticide users on the use of pesticides and its health implications. Consumers are also implored to wash their food very well before consumption so as to remove pesticides that may be present on the seed coat or surface of food produce.

Assessment of Selected Food Products for Pesticide Residue in Major Markets of Oyo State, Nigeria

A study was carried out on the assessment of selected food produce for pesticide residue in Oyo State. With the aid of multi stage sampling technique, 8 selected markets were surveyed in the major constituencies of Oyo State which included Oje and Bodija Market in Ibadan, Arada and Sabo Markets in Ogbomoso, Ajegunle and Araromi Market in Oyo, Owode and Sango Markets in Igboho and Saki respectively in Oke-Ogun. Information on type of pesticide use, reason for choosing the pesticide, method of applying the pesticide and duration of post application storage, were collected. Food produce sampled were yam chips, cowpea, maize and smoked fish for residual analysis. The residual analysis includes extraction of samples, cleaning of extraction and screening of the pesticide using GC-MS to detect any chemical metabolites. The survey reveals that majority (87.5%) of respondents were involved in selling of maize, yam chips and cowpea and the most used pesticide in the market was Aluminium phosphide marketed as phostoxin. Many of respondents applied pesticide by fumigation and the choice of these pesticides was base on customary practices. These food produce are stored for less than a month before being disposed of to consumers. Result from residual analysis shows sample from all the markets contains high percentage of alkane compounds especially the heptadecanes, eicosane, hexadecane and octadecane. Organochlorines were also found in the samples at high percentage. Banned pesticides are still in use in the visited markets and the use of banned pesticide should be prohibited and extension scheme on the use of pesticide on stored produce should be sponsored by government. This will help educate pesticide users on the use of pesticides and its health implications. Consumers are also implored to wash their food very well before consumption so as to remove pesticides that may be present on the seed coat or surface of food produce.

Dichloro-diphenyl-trichloro-ethane (DDT) and hexachlorohexane (HCH) pesticide residues in foodstuffs from markets in Ile-Ife, Nigeria

Levels of dichlorodiphenyltrichloroethanes (DDTs) and Hexachlorocyclohexanes (HCHs) pesticide were evaluated in samples of cowpea grains and dried yam chips obtained from Ile-Ife markets, southwestern Nigeria. The objectives of the study were to establish the presence of the organochlorine pesticide residues in the foodstuffs and also to ascertain whether the residue levels are above their respective permissible levels. Randomly selected samples from highly patronized markets were subjected to standard extraction protocols. The DDT and HCH levels were determined using Gas Chromatography coupled with Electron Capture Detector (GC-ECD). The mean concentration of ϒ-HCH (Lindane) in cowpea grains was 0.085 mg/kg and 0.042 mg/kg in dried yam chips. The ρ,ρ’-DDD concentrations were 0.086 mg/kg and 0.159 mg/kg in cowpea and dried yam chips, respectively. ϒ-HCH detected in all the cowpea samples and 90% in dried yam chips samples were above the recommended EU maximum residue level (MRL) of 0.01 mg/kg. The results of this study indicated that substances that could pose serious health risks were associated, at outrageous levels, with important foodstuffs in Nigerian markets even to the point of sales and consumption. Keywords : Dichlorodiphenyltrichloroethane, hexachlorocyclohexane, pesticide, residue, cowpea grain, yam chip.

English

Yam is one of the most staple foods in West African countries and provides an important part of the energetic for people. This study examines chemical composition of Dioscorea cayenensis and Dioscorea rotundata Poir species dried yam chips obtained using two methods of production in Togo. Three local varieties of yams (Koukou, Keki and Laboco) were processed in chips and were sun dried (at 28-30°C) or oven-dried (at 50°C). Nutritive components (carbohydrates, protein fats, mineral salt, vitamin C and anti-nutritional factors) of yam chips were assessed and compared with those of fresh yam. Sugar is a major component of yam chips followed by proteins, vitamin, fats, mineral salt and anti-nutritionals factors. For the same variety of yam, the nutritional quality depends on the method of production followed and the drying methods. Key words: Yam chips, Dioscorea cayenensis, Dioscorea rotundata, nutritional potential.

Study of Iron Yam-Chip (&lt;i&gt;D&lt;/i&gt;&lt;i&gt;ioscorea&lt;/i&gt;&lt;i&gt; opposita &lt;/i&gt;Thunb. cv. Tiegun) Dehydration Using Far-Infrared Radiation Assisted Heat Pump Drying

Iron Yam chips were dried using a heat pump (HP) dryer alone or in combination with far infrared radiation (FIR) at 500, 1500 and 3000 W (500 FIR, 1500 FIR, and 3000 FIR, respectively). The experimental results were presented in terms of the drying characteristics, and dried product qualities (shrinkage, color, texture, percentage of rehydration, and moisture content). Samples with initial moisture content of approximately 76% (w.b.) were dried to a final moisture content of < 17% (w.b.) at the drying temperature of 50°C and at an air flow rate of 1.0 m s-1 for all of the experiments. The data showed that FIR+HP drying increased the drying rate by reducing the drying time, and the resulted dried Iron Yam chips generally had higher values of lightness and comparable values of redness and yellowness than the HP-treated samples. In the case of HP+1500FIR, the dried Iron Yam chips had lower shrinkage, improved rehydration ability, lower hardness and higher brittleness than those dried by HP, HP+500FIR and HP+3000FIR. It is worth noting that the total energy used for FIR-assisted drying processes decreased with the increase of FIR intensity. The present data suggest that HP+FIR drying is an effective and economical method for Iron Yam chip drying, and HP+1500FIR can obtain the best dried product.

English

Laboratory studies were conducted at the University of Port Harcourt to evaluate the response of dried yam chips as a host for Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae). The test was conducted using four improved yam varieties namely; Adaka, Ame, Nwokpoko and Obiaturugo. Ten grams of each substrate of the dried yam chips were placed in plastic containers of 300 ml and each container was infested with three pairs of one to three days old P. truncatus. Data on insect developmental periods in the various dried chips, as well as the susceptibility of the substrates, weight gain on the chips and the weight of frass produced were recorded. The beetles exhibited differential levels of preference for the yam chips from different varieties. They developed better on Obiaturugo and Nwokpoko than on Adaka and Ame. The mean developmental period of P. truncatus on yam dried chips were 96.33 and 65.33 days for Obiaturugo and Nwokpoko, respectively but failed to develop on Adaka and Ame. There was significant difference (P<0.05) in weight between the amount of frass produced on Obiaturugo and that produced on the other substrates. Also, there was significant difference (P<0.05) in weight gained between Nwokpoko and the other substrates. The study has shown that of the dried chips from the four varieties of yam, only Nwokpoko and Obiaturugo were found to be possible hosts of P. truncatus and thus need protection against the pest during storage. Key words: Prostephanus truncatus, infestation, yam, chips.

Effect of Hydrocolloids and Egg Content on Sensory Quality of Coated Fried Yam Chips

This study investigated the effect of hydrocolloid (xanthan gum, gum tragacanth, and carboxymethyl cellulose) at 0.5–1.5% concentration and egg content (egg white or whole egg) as coating ingredients on the sensory quality of fried yam chips (FYC). The coated chips were evaluated for appearance, texture, taste, flavor, and overall acceptability using a nine-point hedonic scale. Descriptive sensory evaluation of the samples using generic method was also conducted. The studied independent variables had significant (p < 0.05) effects mainly on the appearance and texture of the FYC. Generally, the acceptability scores decreased significantly with increased hydrocolloid concentration (p < 0.05). Appearance had highest significant correlation (p < 0.01, r = 0.764) with overall acceptability. Eight of over fifty descriptors generated by the trained panelists were agreed upon as non-redundant, discriminatory attributes of the coated FYC. Similarity map of the descriptors were defined by two principal components accounting for 53.06% and 40.18% of total variance of rotation sums of squared loadings.

Quality Characteristics of Pre-treated Yam Chips Produced from Irradiated Yams

Quality Characteristics of Pre-treated Yam Chips Produced from Irradiated Yams

Effect of Blanching and Frying on Textural Profile and Appearance of Yam (D ioscorea rotundata ) French Fries

Response surface methodology was employed to characterize the effects of blanching temperature, blanching time and final frying time on texture and appearance of fried yam chips produced from two cultivars of white yam (Dioscorea rotundata). Fifteen treatment combinations were derived from Box–Behnken design (k = 3) and run. Analysis of variance and multiple linear regression analyses were conducted to determine the effects of factors on the texture and color indices and to fit models for predicting the response variables. There were differences in the effects of the same set of factor combinations on textural attributes (hardness, fracturability, cohesiveness, gumminess and chewiness) and color (L, a, b) indices of the two cultivars used. Blanching temperature and frying time had a greater impact on texture and appearance of fried chips than blanching time. Adequately fitted models were derived for predicting the effects of blanching and frying on the textural profile and color of yam chips. Practical Applications Millions of tonnes of yam (Dioscorea rotundata) are cultivated annually; however, very few commercial products have been produced from yam. French fries are hugely popular all over the world, and frozen potato chips have evolved into a multibillion dollar business. Yam shares many characteristics with potatoes (Solanum tuberosum) and can equally be conveniently processed and packed for distribution as frozen chips for French fries production. This study provides information on the effects of processing factors on the quality characteristics of fried yam chips similar to potato French fries to facilitate the process of transforming yam into a convenient food product to meet urban demand.

Effect of the Prevalent Insect Species of Yam Chips on Consumers’ Acceptability of Yam Paste

Abstract A survey was carried out between March and August 2010 to identify insect pests of stored yam chips in Ogbomoso Metropolis, Nigeria. Dried yam chips were randomly obtained from old stocks in 6 local markets within the metropolis on monthly basis. There was a significant (P &lt; 0.05) difference in insect abundance based on month of sampling and insect species. Dinoderus porcellus (Coleoptera: Bostrychidae) was the most abundant species. Other species encountered were Araecerus fasciculatus (Degeer) (Coleoptera: Anthribidae), Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae) and Tribolium castaneum Herbst (Coleoptera: Tenebrionidae). When chips were infested with Dinoderus porcellus and stored for 3 months, reconstituted thick paste (amala) was made from the flour and was evaluated for consumers’ acceptability. Sensory characteristics such as odour, colour, texture, appearance, taste and overall acceptability were significantly (P &lt; 0.05) affected when compared with the paste prepared from the uninfested chips.

Storage Insects on Yam Chips and Their Traditional Management in Northern Benin

Twenty-five villages of Northern Benin were surveyed to identify the constraints of yam chips production, assess the diversity of storage insects on yam chips, and document farmers' perception of their impacts on the stocks and their traditional management practices. Damages due to storage insects (63.9% of responses) and insufficiency of insect-resistant varieties (16.7% of responses) were the major constraints of yam chips production. Twelve insect pest species were identified among which Dinoderus porcellus Lesne (Coleoptera, Bostrichidae) was by far the most important and the most distributed (97.44% of the samples). Three predators (Teretrius nigrescens Lewis, Xylocoris flavipes Reuter, and Alloeocranum biannulipes Montrouzier & Signoret) and one parasitoid (Dinarmus basalis Rondani) all Coleoptera, Bostrichidae were also identified. The most important traditional practices used to control or prevent insect attack in yam chips were documented and the producers' preference criteria for yam cultivars used to produce chips were identified and prioritized. To further promote the production of yam chips, diversification of insect-resistant yam varieties, conception, and use of health-protective natural insecticides and popularization of modern storage structures were proposed.

Effect of Pre-Drying and Hydrocolloid Type on Colour and Textural Properties of Coated Fried Yam Chips

ABSTRACT The effect of pre-drying and coating on colour and texture of yam chips were investigated. The colour parameters studied were lightness index (L*), hue angle (h) and browning index (BI). Peak force (PF) of penetration was observed for texture. Coating pick-up (amount of coating adhering to the samples) prior to frying was determined and moisture content of fried samples was also determined. The type of hydrocolloids used in the coating formulation had significant (p

Spatial distribution of total phenolic content, enzymatic activities and browning in white yam (Dioscorea rotundata) tubers.

Browning in raw and processed yams resulting from enzymes, polyphenol oxidase (PPO) and peroxidase (POD), activities is a major limitation to the industrial utilization of Dioscorea varieties of yams. Two elite cultivars of D. rotundata species were selected to study the spatial distribution of total phenols and enzymes (PPO and POD) activities. The intensities of tissue darkening in fresh yam chips prepared from the tuber sections of cultivars during frozen storage were also studied. Total phenolic content was observed to be highest in the head and mid sections of the cultivars than at the tail end. PPO activity did not have any specific distribution pattern whereas POD activity was found to be more concentrated in the head than in the middle and tail regions. Browning was found to be most intense in the head regions of the two cultivars studied; and was observed to correlate with total phenol and dry matter contents of tubers. Between the two enzymes, POD activity appeared to be more related to browning than PPO.