Starch-rich Foods Research Articles

Changes in the Characteristics of Starch Rich Foods during Quick Freezing (Part 1)

Changes in the Characteristics of Starch Rich Foods during Quick Freezing (Part 1)

Green synthesis of gold nanoparticles with starch–glucose and application in bioelectrochemistry

A method for gold nanoparticle (AuNP) synthesis from buffered glucose and starch solution has been developed and the particles investigated by UV-Vis spectroscopy, transmission electron microscopy (TEM), atomic force microscopy (AFM) and electrochemistry. The synthesis proceeds smoothly in neutral and basic solution. The starch concentration, temperature and chemical nature of the buffers are key factors in the AuNP formation. Glucose and starch are reducing and protecting agents, respectively. Among several inorganic and biological Good's buffers, phosphate and MES buffers give the best results with quite uniform AuNPs. Other buffers do not result in well-defined nanoparticle structures. Typical AuNP diameters from MES and phosphate buffers (PB) are 4 ± 1 nm and 13 ± 2 nm with plasmon band peaks at 521 nm and 523 nm, respectively. The role of the phosphate buffer is mainly to control the pH, while MES is also a synergist with more composite function. AuNPs prepared by this method are stable in solution even after 17 months at room temperature. TEM confirms the crystalline structure of the AuNPs, meaning that the AuNP surfaces are low-index single-crystal facets such as (100), (110) and (111). Electrochemistry of the buffers at such single-crystal gold electrode surfaces has offered a more detailed understanding of the buffer effect. The AuNPs have been successfully used in bioelectrochemistry, and found to efficiently enhance interfacial electrochemical electron transfer of the metalloprotein yeast cytochrome c in homogeneous solution. The synthesis has been extended successfully to direct use of starch-rich foods such as potato, carrot and onion to synthesize AuNPs. The present work thus offers a gentle and non-toxic procedure for the synthesis of monodisperse AuNPs in neutral medium with promising potential for pH sensitive biological or medically related applications.

Hortaliças como alimentos funcionais

Embora remonte às origens da civilização, a relação entre alimentação e saúde nunca foi tão estreita quanto nos dias de hoje. Dietas ricas em gordura, sal e açúcar e pobres em carboidratos complexos, vitaminas e minerais, aliadas a um estilo de vida mais sedentário, são responsáveis pelo aumento de doenças ligadas à dieta, tais como obesidade, diabetes, problemas cardiovasculares, hipertensão, osteoporose e câncer. Há muito tempo acredita-se que o consumo de frutas e hortaliças auxilia na prevenção destas doenças. As hortaliças são um importante componente da dieta, sendo tradicionalmente servidas junto com um alimento protéico e um carboidrato. Elas fornecem não apenas variedade de cor e textura às refeições, mas também nutrientes importantes. As hortaliças têm pouca gordura e calorias, relativamente pouca proteína, mas são ricas em carboidratos e fibras e fornecem níveis significativos de micronutrientes à dieta. Além disso, elas possuem compostos funcionais, que beneficiam uma ou mais funções orgânicas, além da nutrição básica, contribuindo para melhorar o estado de saúde e bem-estar e/ou reduzir o risco de doenças. O desenvolvimento de cultivares mais ricas nestes compostos tem se consolidado como um dos principais focos dos modernos programas de melhoramento genético de hortaliças. Vários destes programas, trabalhando com diferentes hortaliças, estão em andamento no Brasil e no mundo visando aumentar os teores e diversificar os tipos de carotenóides presentes na dieta. Neste trabalho são discutidos os principais aspectos relacionados às hortaliças como alimentos funcionais, bem como são detalhados os principais avanços obtidos nesta área no melhoramento de cenoura e tomate no Brasil.

Identifying biomolecular origins of solid organic residues preserved in Iron Age Pottery using DTMS and MVA

The chemical characterisation of solid organic residues found in ceramic vessels, can provide archaeologists with valuable information about ancient diets. Although several selective analytical techniques have been applied to the analysis of specific classes of compounds, such as extractable lipids, waxes, terpenoids and protein fragments, a non-selective analytical technique is required to characterise and categorise complete solid organic residues. In this study, Direct Temperature-resolved Mass Spectrometry (DTMS) is used for the characterisation of 34 solid residues situated on vessels recovered from an indigenous settlement from the Roman period at Uitgeest – Groot Dorregeest (The Netherlands). Sample preparation is limited to grinding very small samples (5–10 μg) and suspending them in water. DTMS analysis of aliquots (1–2 μL) of this suspension gave information about a broad range of organic compounds, such as lipids, polynuclear aromatic hydrocarbons, markers for residual proteins and polysaccharides, and for newly formed complex condensed polymers. Multivariate analysis of the DTMS spectra identified five different chemotypes: groups of residues with comparable chemical characteristics. The biomolecular origin of each of these chemotypes is identified by comparison with experimentally charred reference materials. The chemotypes A 1 and A 2 consist of charred residues identified as starch-rich foods (mixed with animal or plant products), chemotype C consists of protein-rich charred animal products without starch, chemotype B contains smoke condensates from wood fires, and chemotype D consists of special protein-rich and lipid-free foods or non-food products.

Effect of Raw Potato Composition on Acrylamide Formation in Potato Chips

ABSTRACT: Recent studies have shown that subjecting foods to high temperatures during cooking processes such as frying gives rise to the formation of acrylamide. Several factors including product composition and processing conditions affect the rate of formation of this chemical in starch-rich foods. Low reducing sugar and the amino acid asparagine content is desired when cooking because the formation of acrylamide is attributed to the Maillard reaction that occurs between these food components. The cultivar ‘Atlantic’ was used to determine the effect of potato components (reducing sugars and asparagine) on acrylamide content during frying in a traditional fryer. A model system was developed by infusing leached potato slices with predetermined amounts of glucose and asparagine. Increasing glucose and asparagine content in the slices increased the acrylamide content in the potato chips. Color could not be used as an indication of acrylamide content because potato chips with similar color had very different acrylamide concentrations.

Changes of acrylamide levels in food products during technological processing

Acrylamide represents toxic compound presence of which in heat processed foodstuffs has been proven only recently. This chemical is of a great health concern since it is classified as a human carcinogen by the International Agency for Research on Cancer (IARC). Relatively high amounts of acrylamide have been found mainly in starch rich foods such as potato chips, French fries, roast potatoes, breakfast cereals and crisp bread. Concentrations of this hazardous substance in certain food products may reach up to several mg/kg, depending on the type of raw commodity and the way of its processing. Changes of acrylamide levels in potato chips during frying process were monitored in our study. New analytical procedure employing gas chromatography coupled with high resolution time of flight mass spectrometry (GC/HRTOF-MS) was developed for this purpose. The major factors that affect acrylamide levels in chips such as asparagine and reducing sugars (the main precursors of acrylamide) content in raw potatoes as well as the processing conditions setting (time and temperature) were monitored. Under experimental conditions we used, rapid formation of acrylamide occurred after 150 s, temperature of oil bath was approx. 140°C at that time. In overfried chips the levels of acrylamide exceeded 10 mg/kg.

The effect of guar galactomannan and water availability during hydrothermal processing on the hydrolysis of starch catalysed by pancreatic α-amylase

The effects of water-soluble nonstarch polysaccharides (sNSP) on human metabolism are considered to be beneficial because they decrease postprandial glycaemia and insulinaemia following ingestion of starch-rich foods. The mechanisms by which sNSP attenuate the postprandial rise in blood glucose are not well understood but their presence increases the viscosity of gastrointestinal contents, which affects physiological functions, e.g. gastric emptying and peristalsis. Increased viscosity and decreased water activity during hydrothermal treatment of starch could influence α-amylase action. Using guar galactomannan as a representative of sNSP, we found that galactomannan has a direct noncompetitive inhibitory effect on α-amylase with a K i value of approximately 0.5% (3.3 μM). The inhibition is not time dependent and studies suggest direct binding of the enzyme to galactomannan; the resulting galactomannan–amylase complex being inactive. Processing of starch at low water levels greatly affects the catalytic efficiency of α-amylase. The K m value for starch heat treated in limited water is raised and k cat is lowered relative to starch gelatinised in excess water. Since galactomannan has no effect on the K m of α-amylase, we conclude that the inhibitory action of the polymer is not secondary to a decrease in available water. Neither does it seem to be a consequence of impaired diffusion of enzyme, substrate and products because of an increase in viscosity of the medium. Thus, the effects of sNSP in lowering postprandial glycaemia not only involve modifications of gut physiology, but also include direct inhibition of the first stage in the biochemical degradation of starch.

Determination of non-volatile compounds of different botanical origin Brazilian honeys

The levels of water, HMF, free proline, total acidity, diastase activity, fructose and glucose in 74 different floral type honeys from four Brazilian regions are reported. The majority of the samples showed adequate water and HMF contents indicating the use of good practices by beekeepers in Brazil. Large variation in the contents of proline (389–520 mg/kg) was found in the honeys from the four regions studied. These findings are presumably due to the more intensive labor of the bees on the collected nectar by adding gland secretions. The high amount of diastase (40–120°G) found in some honeys from the northeast region could be due to the visit of the bees to Manhiot sp. (cassava) flour factories to collect starch-rich food, consequently increasing the diastase activity in the honey. Xerotolerant yeasts may be responsible for higher total acidity and ratios below 1 for fructose/glucose found in some samples. The majority of the analysed honeys (82%) were within the limits of the European Codex Honey Standards and Brazilian legal regulations.

Efficacy of a preschool breakfast program in reducing refined sugar intake

The objective of this study was to measure nutritional differences between breakfasts eaten at home and those eaten in a preschool setting, which were prepared and served following the guidelines of the School Breakfast Program (SBP). During the fall semester, baseline data on children's breakfasts were obtained from families of 3- and 4-year-old children attending our laboratory school. Two weeks later, we began providing breakfasts for the children at preschool, before they began their school day. Breakfast menus varied but were always in compliance with SBP guidelines. Six weeks after initiating the SBP, we recorded breakfasts eaten at school, and the entire procedure was repeated during the spring semester. Children's intake of macronutrients from the breakfast meal was altered through participation in the SBP. During each intervention period, the consumption of starch-rich foods and fibre increased while the intake of simple sugars decreased. Protein, fat, and micronutrient intake were not affected. The implementation of the SBP appeared to be an effective way to increase the intake of starch-rich foods and fibre in a low-risk sample of preschool-aged children who regularly ate breakfast prior to their participation in this investigation.

Eating style in seasonal affective disorder: Who will gain weight in winter?

Patients with seasonal affective disorder (SAD) selectively eat more carbohydrates (CHO), particularly sweets but also starch-rich foods, during their depression in winter. The Dutch Eating Behaviour Questionnaire (DEBQ) was administered to female SAD patients, healthy female controls, and female medical students to determine their eating style, together with the modified Seasonal Pattern Assessment Questionnaire (SPAQ+). SAD patients showed higher values for “emotional” (EMOT) eating than the students, and these in turn had higher values than the controls. In comparison to controls, SAD patients and students had high values for the factor “external” (EXT) eating, but there was no difference between the groups with respect to “restraint” (REST) eating. This is in strong contrast to patients with bulimia and anorexia nervosa, who are high REST eaters, indicating that SAD patients do not have a similar eating disorder. Additional items showed that SAD patients selectively eat sweets under emotionally difficult conditions (when depressed, anxious, or lonely). Configural frequency analysis showed that seasonal body weight change (SBWC) is high in subjects with high EMOT and REST eating together with a high body mass index (BMI). This result is in accordance with the concept of disinhibition of dietary restraint in extreme emotional situations, e.g., the depressive state.

Dietary carbohydrates in diabetes

Recent recommendations for dietary treatment of diabetes mellitus aim at a diet low in fat and rich in carbohydrates and dietary fiber. The main rationale for an increase of carbohydrates is the desire to reduce the content of fat, especially saturated fatty acids, without a concomitant increase of dietary protein. There are also indications that an increase of carbohydrate-rich foodstuffs can contribute to an improved metabolic profile. Not only the type of food but also its structure is of importance for the blood glucose and hormone responses after a meal. A diet containing approximately 55% of energy from carbohydrates (corresponding to < or = 30% of energy from fat) with a modest increase of dietary fiber to > or = 3 g/MJ, concentrating on soluble fiber and starch-rich foods with a low glycemic index, will probably be adequate for most patients with diabetes. However, diets with somewhat higher or lower contents of carbohydrates may be more suitable for some patients because dietary advice should always be individualized on the basis of energy requirements, age, metabolic profile, and food habits of the patient.

Starch and sugar tastes in rodents: An update

Rats are strongly attracted to the sweet taste of sugar. Recent behavioral studies demonstrate that rats also have a well-developed taste for starch-derived polysaccharides (e.g., Polycose). In fact, rats prefer Polycose to sucrose and other sugars at low concentrations. Polycose appetite develops at a very young age (9 days) and, thus, appears to be innate. The results of conditioned taste aversion tests suggest that rats taste Polycose as qualitatively different from sucrose. Recent electrophysiological findings support the idea that rodents have separate taste channels for polysaccharides and sugars. In particular, copper chloride suppresses the chorda tympani nerve response to sucrose and other sugars but has minimal effect on the neural response to Polycose. Also, Polycose evokes a profile of neural activity in the nucleus tractus solitarius that differs substantially from that produced by sucrose. Preliminary results indicate that polysaccharide and sugar tastes also differ in their metabolic consequences i.e., unlike sugars, Polycose does not elicit a cephalic phase insulin response. The presumed function of polysaccharide taste is to facilitate the identification of starch-rich foods. Recent findings demonstrate that rats can readily detect starch even at low concentrations, but whether polysaccharide taste receptors or other orosensory receptors mediate this response remains to be clarified.

Chemoreception for an insoluble nonvolatile substance: starch taste?

Substances that are insoluble in both water and lipids, such as starch, are commonly assumed to be tasteless. Starch was suspended in water with a viscous gum. Rats given a choice of fluid containing starch and the same fluid without starch consistently preferred fluids containing starch. Rats were able to detect as little as 0.5% starch from several species of plants (corn, rice, wheat, and potato). In contrast, rats ignored comparable concentrations of cellulose suspended in water. Rats were also capable of choosing the fluid containing higher levels of starch when given a choice of 1 vs. 2% starch or 0.5 vs. 1% starch. This ability to detect starch did not appear to be mediated by salivary alpha-amylase because 1) raw starch is highly resistant to hydrolysis by salivary amylase, 2) starch preference was not correlated with the susceptibility of the starch to hydrolysis by salivary amylase, and 3) starch preference was not blocked by partial or extensive desalivation. Attempts to extract impurities with either organic solvents or water did not provide any evidence that such impurities contribute to starch preference. These experiments point to a seemingly novel form of chemoreception that could be useful to animals that need to identify starch-rich foods.

Plant cell walls and monogastric diets

A brief summary is given of the recent and progressing research at the Swedish University of Agricultural Sciences in development of analytical methodology for plant cell wall components (dietary fiber) and mixed-linkage β-glucans. Applications of the methods for the chemical characterization of various types of human and monogastric animal foods will be presented, including heat-processed, starch-rich foods. In the latter group Maillard reaction products, “resistant starch” and chemically transformed starch increase the dietary fiber values. Nutritional studies on the role and properties of plant cell wall materials in connection with bile acid and cholesterol metabolism in hamster and with digestion of pig and poultry diets will be discussed.

Nutritional beliefs among rural Nigerian mothers.

At Shao, a rural community in Nigeria, 730 women were asked to state their awareness of pregnancy symptoms and nutritional beliefs during pregnancy. Among the participants, 92.3% mentioned the stoppage of menstruation while 81.9% recognized breast enlargement, 16.2% considered nausea and vomiting, and 5.3% mentioned the darkening of the nipples. Specific foods of the protein rich meat group, particularly rabbit Oryctolagus capensis was avoided during pregnancy because of sociocultural beliefs. Energy-giving starch-rich food items were most frequently regarded as good for the body. Over 50% of the respondents considered the roots, the starchy food group, and the fruits and vegetables group as most nutritious during pregnancy. Only 38.8% of the respondents met the recommended weekly weight gain standard and 61.2% did not. It was recommended that a statewide classification of food taboos in Kwara State should be undertaken to assist the services provided by primary healthcare workers. The need to intensify health counseling in antenatal care clinics was highlighted.

Insulinemic and glycemic indexes of six starch-rich foods taken alone and in a mixed meal by type 2 diabetics

The glycemic index concept neglects the insulin secretion factor and has not been systematically studied during mixed meals. Six starch-rich foods were tested alone and in an isoglucido-lipido-protidic meal in 18 NIDDs and compared with a glucose challenge. These test meals were randomly assigned using a three factor experiment design. All three tests contained 50 g carbohydrate; mixed meals were adjusted to bring the same amount of fat (20 g), protein (24 g), water (300 mL), and calories (475 kcal) but not the same amount of fiber. Whatever the tested meals, foods elicited a growing glycemic index hierarchy from beans to lentils, rice, spaghetti, potato, and bread (mean range: 0.21 +/- 0.12-92 +/- 0.12, p less than 0.001). Mixing the meals significantly increased the insulinemic indexes (p less than 0.05) and introduced a positive correlation between glycemic and insulinemic indexes (n = 6, r = 0.903; p less than 0.05).The glycemic index concept remains discriminating, even in the context of an iso-glucido-lipido-protidic meal. Insulinemic indexes do not improve discrimination between foods taken alone in type 2 diabetics: they only discriminate between foods during mixed meals, similarly to glycemic indexes.

Dominance at Adh locus in response of adult Drosophila melanogaster to environmental alcohol.

IT has been argued1 that natural selection acting on enzyme polymorphisms may be most clearly demonstrated by challenging polymorphic populations with an environmental additive acting as a specific substrate for the enzyme under study. Wills and Nichols2, for example, showed that, in their experimental conditions, heterozygote advantage at the octanol dehydrogenase locus in D. pseudoobscura depended on the presence of octanol in the food medium. Similarly, de Jong et al.3 found that the amylase4,6 variant increased strikingly in frequency in populations of D. melanogaster moved from a sucrose to a starch-rich food medium. Amy4,6 is known to possess the highest in vitro activity on starch substrates of all common amylase variants4. We have examined the relationship between mortality and genotype at the alcohol dehydrogenase (Adh) locus when adult Drosophila are exposed to environmental ethanol.

Assimilation of ammonia nitrogen by rumen bacteria.

AMMONIA is always present in the rumen liquor of sheep1 and the concentration varies with the kind of protein in the ration, but the addition of starch-rich foods such as maize meal or flaked maize to high-protein rations depresses the concentration2–4.