Lea Hyvönen

Food Technological Evaluation of Xylitol

Publisher Summary This chapter discusses that Xylitol occurs widely in nature. Frerejacque showed the occurrence of xylitol in lichens, seaweed, and yeast. Kratzl and Silbernagel found xylitol in mushrooms. Xylitol is by no means a new substance, having been first prepared as a syrup 90 years ago, almost simultaneously in the laboratories of Bertrand and Fischer and Stahel. Production of xylitol by means of extraction from its natural sources is impractical and uneconomical because of the relatively small amounts in which it occurs. In mass production, plant material is treated with a dilute acidic solution under heat and pressure to hydrolyze the hemicelluloses and to precipitate the lignins. Chewing gum is a cariogenic product, since through constant release of sugar during chewing the time of contact with the teeth is quite long and intensive. Hard caramels (hard candy, high-boiled sweets) represent another class of high-caries-risk confectionery. In principle, sucrose can be replaced by xylitol on a weight basis in ice cream. In jams, jellies, and marmalades sugar acts as a preserving agent by its osmotic pressure. For the sake of complete replacement of sucrose by xylitol, the test subjects in the Turku sugar studies were regularly provided with fresh bakery products. The chapter discusses that because of its laxative effect xylitol alone is not recommended in beverages—such as—soft drinks, where consumption may easily exceed the recommended single dose intake. It is realistic to expect only a relatively small future replacement of sugar by xylitol.

Analysis of lipid classes by solid-phase extraction and high-performance size-exclusion chromatography

An improved method to analyze lipid classes of edible oils and fats by solid-phase extraction (SPE) and high-performance size-exclusion chromatography (HPSEC) is presented. A mixture of lipid standards was fractionated by the solid-phase extraction procedure (NH2 phase) into polar and nonpolar fractions; these were then submitted to analysis by HPSEC. The size-exclusion chromatographic columns were three styrene/divinylbenzene columns with pore sizes of 100 Å and 50 Å. Light-scattering was used for the detection system, and the parameters of the detector were optimized to minimize the difference between the responses of the compounds studied. With this procedure it was possible to separate the following lipid classes: triacylglycerols, diacylglycerols, monoacylglycerols and free fatty acids, sterols, sterol esters, tocopherols and carotenoids. Quantitative analysis was studied for a light-scattering detector with several lipid standards of different molecular weights and unsaturation levels.

Dietary cholesterol, fatty acids, and the risk of lung cancer among men

The relation between dietary cholesterol and fatty acids and the incidence of lung cancer was studied among 4,538 Finnish men aged 20-69 years and initially free of cancer. During 20 years of follow-up, 117 lung cancer cases were diagnosed. Cholesterol intake was not associated with lung cancer risk, the age-, smoking-, and energy-adjusted relative risk between the lowest and highest tertiles being 1.0 [95% confidence interval (CI) = 0.6-1.9]. The intake of saturated fatty acids was nonsignificantly related with lung cancer incidence, the relative risk for the lowest compared with the highest tertile being 1.6 (CI = 0.8-3.2). The association was stronger among smokers than among nonsmokers, the relative risks being 2.1 (CI = 1.0-4.3) and 1.3 (CI = 0.4-4.1), respectively. The relative risk among smokers, however, decreased to 1.5 after adjustment for the amount they smoked. In the total cohort, there was a significantly elevated risk of lung cancer among men with a high intake of butter, one of the main sources of saturated fatty acids, the relative risk being 1.9 (CI = 1.1-3.2). The present data do not confirm previous results suggesting that dietary cholesterol predicts the occurrence of lung cancer among men. The association between intake of saturated fatty acids and lung cancer observed in the present study may be partly due to heavy smoking among high consumers of saturated fat.

Application of High-Performance Size-Exclusion Chromatography to Study the Autoxidation of Unsaturated Triacylglycerols

A combination of solid-phase extraction (SPE) and high-performance size-exclusion chromatography (HPSEC) was used to study the autoxidation of triacylglycerol (TAG) mixtures separated from low-erucic acid rapeseed oil and butter oil. The samples were autoxidized in the dark at 40°C for four weeks. The polar compounds of the autoxidated samples were separated by SPE (NH2 stationary phase), and the polar fraction was further characterized by HPSEC with a series of three size-exclusion columns and an evaporative light-scattering detector. The polar fraction contained TAG polymers, polar TAG monomers (PTAG) and diacylglycerols. Peroxide values and anisidine values of the samples were also measured. By using three different types of TAG mixtures, it could be demonstrated that the PTAG content of the TAGs increases during autoxidation. A slight increase was also detected in polymer content. The correlation between PTAG content and the comparative measurements was considered significant. The results indicate that the measurement of PTAG and polymeric material content by HPSEC analysis can be used when studying the autoxidation level of edible oils and in characterizing the autoxidation products of different molecular sizes.

Dairy fat content and serving temperature as determinants of sensory and hedonic characteristics in cheese soup

Abstract The effect of fat content and serving temperature on sensory and hedonic responses were studied using cheese soup samples with 3, 6 or 12% dairy fat, served at 33, 48 or 63 °C. A trained panel ( n = 13) rated the intensity of eight sensory characteristics. The pleasantness of the samples was rated by 36 consumers, who also rated their liking for 26 foods listed in a questionnaire. Increasing fat content intensified perceived fattiness, thickness and flavour attributes. Odour intensity was perceived to be strongest in hot samples. No interaction was observed between fat and temperature in the sensory ratings, whereas, in the pleasantness ratings, the two factors mutually influenced one another. The sample with the highest fat content and temperature was rated highest in terms of pleasantness, while, at the lowest temperature, the increasing fat content was incapable of enhancing pleasantness. Reported liking for high-fat foods was related to low pleasantness of the samples, which suggests that cheese soup is regarded as a ‘light’ product.

Does fat affect the timing of flavour perception? A case study with yoghurt

Abstract Sweetness and sourness intensities of strawberry yoghurts containing 0.1 or 5.2% dairy fat, 6 or 12% sucrose, and 1.1% lactic acid, were rated by 14 assessors in two replications, using the time-intensity procedure. The timing of sweetness and sourness perception in this watercontinuous material was unaffected by the fat content of the samples.

Effect of Sampling Site on Retinol, Carotenoid, Tocopherol, and Tocotrienol Concentration of Adipose Tissue of Human Breast with Cancer

The effect of sampling site and closeness of malignant tumor on the retinoid, carotenoid, tocopherol, and tocotrienol concentration of adipose tissue of human breast was studied in 10 cases of breast cancer. The four anatomic quadrants of breast did not differ from each other statistically significantly in relation to adipose tissue concentrations of the vitamins studied. Proximity of malignant tumor did not affect the vitamin concentrations when compared to the more distant sampling sites. Representative sample of breast adipose tissue for vitamin concentration analysis can be obtained from tissue adjacent to the tumor.

Approach to fat analysis of foods

Abstract Behind the nutritional labelling of food fat hides a problem of definition of fat, as well as an analytical problem. Although triacylglycerols are the prevailing structure of the food lipids in most cases, there are exceptions, too. Analytes called ether extract, crude fat, total fat and total lipids have been interpreted to food fat in nutritional labelling and food databases. However, the techniques traditionally used for fat determination in foods may vary considerably in their ability to recover the various lipid components. Diversity in the lipid composition of various foods and the effects of processing and storage on the diversity and availability of the fat make the correct nutritional labelling of fat problematic. The traditional methods, where the total fat content is determined by extracting the fat with an appropriate fat solvent or a solvent mixture, give good technical measures. The use of this extracted fat-soluble material as the nutritional concept of fat may be misleading. We have suggested (Hyvonen et al. , 1993, J. Food Comp. Anal. , 6 , 24–40) the use of the concept of net fat in nutritional food labelling. This definition of fat includes all the unchanged fatty acids from the various food lipids converted to triacylglycerols. In energy calculations 1 g of net fat corresponds to 9 kcal or 38 kJ. This concept reduces the energy values of foods because it eliminates the lipid components, which are not real fats, from the calculation.

Effect of sampling site on fatty acid composition of human breast adipose tissue.

The effect of sampling site and proximity of malignant tumor on the relative fatty acid composition of human breast adipose tissue was studied in 10 cases of breast cancer. The four anatomic quadrants of breast did not statistically significantly differ from each other in relation to any of the 30 fatty acids studied. Proximity of the malignant tumor did not affect the relative fatty acid composition of fat when compared with more distant sampling sites. Representative samples of breast adipose tissue for fatty acid composition analysis can be obtained from tissue adjacent to the tumor.