Resistant starch content and glucose release of different resistant starch commercial ingredients: effect of cooking conditions

The suitability of different commercial ingredients rich in resistant starch (RS), two granular RS (RS type 2) and two retrogradated RS (RS type 3), as sources of RS in different enriched foods (muffins, and battered food prepared by two methods differing in their thermal treatment) was studied. The appropriateness of the official method of fibre analysis to detect RS and the application of RS in muffins to reduce the glucose released during in vitro food digestion were also investigated. In RS-enriched muffins, the RS content resulted not affected by oven baking. In fried battered food, a reduction of RS content took place after frying, this reduction being dependent on the type of RS-ingredient. In general, RS type 3 ingredients showed higher cooking stability than RS type 2. The thermally milder method for fried food showed higher final RS content in comparison with the thermally more severe one. In vitro simulation of human digestion showed lower glucose release in RS-enriched muffins, especially in RS type 3, in comparison with the control (no RS). Although RS is considered dietary fibre, the official method of fibre analysis (AACC International 32-07.01-AOAC 991.43) underestimated its content value in comparison with the official method for RS analysis (AACC 32-40.01-AOAC 2002.02).     

Evaluation of methods of analysis for dietary fibre using real foods and model foods

Rationale and objectives

There are several rational and empirical methods for the measurement of dietary fibre and its components. A selection of these methods were evaluated by investigation of a range of real foods and model foods with added resistant starch (RS), non-starch polysaccharides (NSP) and resistant oligosaccharide (RO) ingredients.

Methods

A range of rational methods were applied in determining specific carbohydrate constituents: RS, NSP and RO, including fructans. For comparison, empirical methods AOAC 991.43 (2001.03) and AOAC 2009.01 were applied, based on determination of gravimetric residues for high molecular weight and size-exclusion HPLC analysis of the ethanol filtrate for low molecular weight components.

Results

In general there was agreement between different rational methods for the analysis of RS and fructans, though there were notable exceptions for some product types. Comparison of methods for total RS and those that only measure the RS3 fraction, from retrograded starch, indicated that RS3 was the only type present for most processed products. This also explains the similar results obtained by AOAC 991.43 (2001.03) and AOAC 2009.01, though the latter is intended to recover other RS types as well. For many products there was agreement between results obtained by rational and empirical methods, though there were exceptions and the reasons for these are discussed.

Conclusion

Rational and empirical methods can both be used to determine dietary fibre in most situations. The information provided by rational methods is useful in identifying the specific carbohydrate constituents present in foods and can assist in determining whether added extracted and synthesised ingredients are ones that conform to the Codex and EU dietary fibre definition.     

Dietary fibre fractions in cereal foods measured by a new integrated AOAC method

The reliable determination of soluble, insoluble and total dietary fibre in baked goods and cereal flours is an important issue for research, nutritional labelling and marketing. We compared total dietary fibre (TDF) contents of selected cereal based foods determined by AOAC Method 991.43 and the new AOAC Method 2009.01. Fifteen bread and bakery products were included in the study. Our results showed that TDF values of cereal products determined by AOAC Method 2009.01 were always significantly higher than those determined by AOAC Method 991.43. This was explained by the inclusion of low molecular weight soluble fibre fractions and resistant starch fractions in the TDF measurement by AOAC 2009.01. This documents that nutritional labelling of cereal products poses the challenge how to update TDF data in nutrient databases in a reasonable time with an acceptable expenditure.     

Initial interlaboratory validation of an analytical method for the determination of lead in canned tuna to be used for monitoring and regulatory purposes

The Association of Official Analytical Chemists (AOAC) Standard Method 972.23 (dry ashing and flame atomic absorption spectrophotometry (FAAS)), applied to the analysis of lead in tuna, was validated in three selected local laboratories to determine the acceptability of the method to both the Codex Alimentarius Commission (Codex) and the European Union (EU) Commission for monitoring lead in canned tuna. Initial validation showed that the standard AOAC method as performed in the three participating laboratories cannot satisfy the Codex/EU proposed criteria for the method detection limit for monitoring lead in fish at the present regulation level of 0.5 mg kg^-1. Modification of the standard method by chelation/concentration of the digest solution before FAAS analysis showed that the modified method has the potential to meet Codex/EU criteria on sensitivity, accuracy and precision at the specified regulation level.     

Improvement of the AOAC 2009.01 total dietary fibre method for bread and other high starch containing matrices

The dietary fibre (DF) content in wheat grain based food products have been established with both the classical AOAC 985.29 dietary fibre and the new AOAC 2009.01 total dietary fibre protocol. There is a good agreement between the high molecular weight dietary fibre (HMWDF) contents measured with the AOAC 2009.01 method and (DF) content measured with the classical AOAC 985.29 method in wheat grain based food products. With the AOAC 2009.01 method also a significant amount of low molar weight dietary fibre (LMWDF), ranging from 1% to 3% w/w, was measured which is not quantified with the AOAC 985.29 method.     

Dietary fibre content of dry and processed beans

Common beans (Phaseolus vulgaris L.) are a good source of protein, vitamins, minerals and especially dietary fibre. As beans are never eaten raw, the effects of soaking, cooking, soaking–cooking and canning on soluble, insoluble and total dietary fibre contents of beans are studied. Total dietary fibre content was determined by enzyme-gravimetric method. The fraction of insoluble dietary fibre was corrected for the content of resistant starch, determined as part of the total starch in insoluble fibre. The results indicate that thermal processing decreased the insoluble fibre content, and consequently the total dietary fibre content of beans. Soaking and cooking of beans significantly (P⩽0.05) increased the resistant starch content. The data on dietary fibre content of processed food are much more relevant than those of raw food. Thus food composition tables should contain as much data on processed food as possible.     

Fermentation of resistant food starches by human and rat intestinal bacteria

Resistant starches prepared from maize and peas were fermented in vitro with rat or human intestinal bacteria. With both inoculum types, degradation of pea starch after 24 h incubation (0 and 47% utilised by rat and human organisms, respectively) was markedly slower than that of maize starch (73 and 85%) and was incomplete even after 7 days' incubation; degradation of both starches was slower than with soluble starch or sucrose. The slow degradation of pea starch was not due to the presence of intact cell walls. Qualitatively, the production of C2-C4 volatile fatty acids was similar for all substrates and both inoculum types but there were some quantitative differences. If resistant food starches are to be regarded as dietary fibre, then, like ‘true’ fibre, any physiological effect in vivo may depend on the type of starch involved.     

An approach to the influence of nutrients and other food constituents on resistant starch formation

The influence of nutrients and other food constituents, such as dietary fibre components, catechin and phytic acid, on resistant starch (RS) formation was systematically investigated. This investigation was carried out under standardized gelatinization conditions by using a high pressure autoclave (HPA). Except for insoluble dietary fibre constituents (cellulose and lignin), all the tested food ingredients reduced the formation of RS. Calcium ions, potassium ions and catechin showed the highest reduction of RS formation, while the nutrients studied (albumin, olive oil and sucrose) as well as phytic acid affected it to a lesser extent. These results were not significantly changed by varying amounts of the studied dietary components.     

An introduction: Evolution and finalisation of the regulatory definition of dietary fibre

It is more than 56 years since Hipsley (1953) first used the term dietary fibre for the non-digestible constituents of plant cell walls and more than 30 years since 14 and 13 adopted the term and suggested a definition for “dietary fibre”. Since this time there has been no accepted international regulatory definition until Codex adopted a final definition in its 2009 meeting. The sequence of these protracted discussions and consequential evolving views about dietary fibre regulatory definitions are here reviewed.     

EVALUATION OF DIETARY FIBER IN POTATO CRISPS: INFLUENCE OF THE ANALYTICAL METHOD USED

Dietary fiber in ready salted potato crisps was determined by two methods, i.e., the official AOAC method, and the modified method of Englyst, recommended in the U. K. The ultimate aim was to compare the results and to evaluate the advantages and limitations of each method for the analysis of this food in order to obtain a figure to be included on the package. The AOAC method is an enzymatic-gravimetric procedure to determine the total dietary fiber (TDF). The Englyst method consists of an enzymatic-chemical extraction and fractionation of the nonstarch polysaccharides (NSP) and their subsequent determination as neutral sugars by GLC. We modified the original chromatographic method. The AOAC method gave a value of 5.39 g/100g (dry matter) for TDF, and the Englyst method of a value of 1.70 g/100g (dry matter) for NSP. It is assumed that the gravimetric method gives a higher fiber value than the Englyst method due to a contribution from retrograded starch. For this particular food, the AOAC method is faster and much easier to carry out and does not overestimate dietary fiber, if the resistant starch is regarded as part of it.     

Profiles of phenolic compounds of Apis mellifera and Melipona spp. honeys from Venezuela

 The size of the indigestible fraction of, and the availability of starch in, commercial frozen and canned peas was studied in vitro. The total dietary fibre content, as determined by chemical analysis, was similar in both samples (27%); nevertheless, appreciable amounts of resistant starch (4.4–6.9%) and resistant protein (4.7–5.4%) were found in the insoluble dietary fibre gravimetric residue. Other indigestible components of the pea were an additional fraction of resistant starch, not associated with insoluble dietary fibre, and the oligosaccharides inulin and stachyose. The total amount of starch (25.8–36.1%) was very different between frozen and canned samples, and was inversely correlated with their sucrose contents (14.2–6.7%). Our results indicate that 35–40% of the dry weight of peas is not digested in vitro and that the relative rate of glucose release by α-amylase hydrolysis seems to be decreased in the presence of resistant starch. Received: 8 October 1996     

International legislation on trace elements as contaminants in food: a review

Environmental contaminants such as trace elements may be present in all foods. Foods, raw materials and ingredients for food production are to an increasing extent traded across borders. Hence, there is a need for international legislation on trace elements as contaminants in food. In 1961, the FAO and WHO established the Codex Alimentarius to elaborate international food legislation. Contaminants in food are handled by the Codex Committee for Food Additives and Contaminants (CCFAC). The Codex Alimentarius system for developing legislation concerning trace elements as contaminants in food is based upon the Codex General Standard for Contaminants and Toxins in Food (GSCTF). By October 2001, the principles for setting maximum limits (MLs) for contaminants in food are agreed, and work is in progress on MLs for trace elements such as lead and cadmium in the various food categories. The status for the proposals is presented and discussed. The EU Regulation 466/2001 of 8 March 2001 sets MLs for lead and cadmium in various foods. This regulation will apply from 5 April 2002. The EU regulation is more detailed but similar to the Codex draft standards for lead and cadmium in food. In future, legislators and administrators in the Codex and EU and analytical chemists will discuss how to use more and better analytical data as risk-management tools to protect public health. Trace elements' speciation is an important aspect of this discussion.     

日本进口食品检验检疫制度综合分析

日本进口食品检验检疫制度是在1951年建立的,1994年该制度得到了完善。该制度制定的法律依据是《食品卫生法》。其抽检比例的制定参考了国际食品法典委员会抽样分会提示的食品抽检方法,是一种国际上通行的方法,正式形成了日本进口食品检验检疫制度。日本对进口食品的检验检疫形式主要有2种,一为监控检查,二为命令检查。命令检查措施之后尚有全面禁止进口措施。这一制度具有一定法律依据,监控检查措施和命令检查措施严密,处罚措施和解除措施严格,可根据市场需求趋严趋紧,显现了很强的可操作性,长期以来我国出口企业深受该制度的约束,这一制度为日本调控进口食品贸易平衡起到了重要作用。对这一制度的了解,无论对管理部门或企业都显得十分重要。     

中国与国际食品法典委员会动物食品兽药残留标准的比对分析

目的 对中国现行的新兽药残留标准与国际食品法典委员会的兽药残留限量指标进行比对,并对结果进行分析。方法 对我国标准与国际食品法典委员会标准中规定的兽药种类、涉及的物种及部位、残留限量进行逐级比对。我国兽药限量相关标准为GB 31650-2019《食品安全国家标准食品中兽药最大残留限量》,以及农业农村部公告第250号;国际食品法典委员会标准为CX/MRL 2–2018《食品中兽药残留的最大残留限量和风险管理建议》。结果 在可比指标中,我国与国际食品法典委员会限量相同的指标有316个,占全部可比指标的94.3%;我国比国际食品法典委员会更为严格的兽药残留限量指标有12个,占全部可比指标的3.6%;我国比国际食品法典委员会标准宽松的指标有7个,占可比指标总数的2.1%。结论 我国动物食品中兽药残留标准中,97.9%的可比指标达到或超过国际食品法典委员会标准规定。     

抗性淀粉对馒头的感官评价及物性的影响

抗性淀粉的特性与膳食纤维基本相似,但它又不同于膳食纤维。抗性淀粉添加到食品中后,它不会像膳食纤维那样影响食品的感官和质构。但当较高含量的抗性淀粉添加于小麦粉中,在一定程度上恶化了小麦粉的加工性能。实验证明：将中筋粉中添加5%左右的抗性淀粉制作馒头,既可保证馒头的保健品质又不失其食用品质及感官品质。     

New starch preparations resistant to enzymatic digestion

BACKGROUND: New starch preparations were produced by thermolysis of potato starch in the presence of inorganic (hydrochloric) and organic (citric and tartaric) acids under controlled conditions. The starch preparations were physicochemically and structurally characterised and analysed for their resistance to enzymatic digestion in vitro. RESULTS: The content of resistant fraction in dextrin D1, obtained by heating starch acidified with hydrochloric and citric acids, determined by the AOAC 2001.03 and pancreatin‐gravimetric methods was similar (～200 g kg^?1). In the case of dextrin D3, obtained by heating starch acidified with hydrochloric and tartaric acids, the result of determination by the pancreatin‐gravimetric method was almost four times higher than that obtained with the AOAC 2001.03 method. The enzymatic tests revealed that dextrin D3 obtained with excess tartaric acid can be classified as RS4, which can only be partially determined by enzymatic‐gravimetric methods. Tartaric acid at high concentration had a significantly stronger influence on starch hydrolysis than citric acid. This was confirmed by chromatographic analysis of dextrins and chemical investigation of the reducing power. CONCLUSION: The results confirmed the possibility of applying dextrins, prepared under specific conditions, as soluble dietary fibre. Copyright © 2011 Society of Chemical Industry     

Dietary carbohydrates: classification by chemistry and physiology

Food carbohydrates consist of mono-, di-, oligo- and polysaccharides, the latter composed of starch and non-starch polysaccharides (NSP). The glycaemic response to both sugars and starches is dependent on the types of sugars present and the form of the starches, and ‘complex carbohydrates’ do not necessarily produce slower or lower glycaemic responses than the sugars. Carbohydrates not absorbed in the small intestine are fermented more or less extensively by the large intestinal microflora. There is a fundamental difference nutritionally between digestible and undigestible (‘unavailable’) carbohydrates. NSP, resistant starch (RS) and oligosaccharides are the main forms of undigestible carbohydrates. Dietary fibre is generally conceived as more or less synonymous with ‘unavailable’ carbohydrates. The nutritional effects of dietary fibre are related to its undigestibility in the small intestine, and to the physical and chemical properties of its constituent polysaccharides. Food structures built of dietary fibre as plant cell-walls, and also of other food components, are increasingly recognized as nutritionally important. Food databases should include as much specific and detailed information as possible on food carbohydrates. For food labelling, carbohydrates have to be divided into a number of nutritionally meaningful classes. A first classification should then aim at differentiating the digestible and undigestible carbohydrates, i.e. dietary fibre.     

抗性淀粉制备研究

抗性淀粉是一种新型的膳食纤维资源。研究不同抗性淀粉的制备方法对促进该产品的工业化生产具有重要意义。介绍了4类抗性淀粉的制备方法,简述了脂类、糖等食品成分对抗性淀粉形成的影响。     

Towards an updated methodology for measurement of dietary fiber,including associated polyphenols,in food and beverages

The analytical dietary fiber (DF) methods most widely used today were developed to determine non-starch polysaccharides and lignin. Updated dietary fiber definition includes all indigestible plant food constituents. Recent methods have proposed the measurement of resistant starch and oligosaccharides, but other major indigestible constituents such as polyphenolic compounds and resistant protein are still omitted in dietary fiber analysis. There is scientific evidence that an appreciable amount of dietary polyphenols are associated with the dietary fiber matrix, being a fermentable substrate for bacterial microflora. The objective of this work was to show polyphenols compounds are major constituents of dietary fiber and to propose a procedure for their measurement. Results showed that polyphenols are major constituents of DF, accounting from 1.4% to 50.7% (dry weight) of insoluble dietary fiber in plant foods and from 2.9% to 62.8% of soluble dietary fiber in common beverages.     

国外“无麸质”食品的管理

为了规范"无麸质"(gluten free)食品标识,国际食品法典委员会、欧盟、美国、加拿大以及阿根廷等国相继发布了无麸质食品的相关法规或标准,定义了无麸质食品,提出了无麸质食品的质量控制、标注以及检测等方面的要求,并提出了管理及发展我国"无麸质"食品产业的对策。