Single courier single restaurant meal delivery (without routing)

We investigate optimization models for meal delivery that do not involve routing. We focus on the simplest case, with a single restaurant and a single courier, and reduce it to the throughput maximization single machine scheduling problem, with release times and bounded slacks. In the meal delivery setting, slacks are small for QoS purposes and we indeed show that the scheduling problem can be solved in polynomial time when slacks are bounded. We discuss extensions to more couriers and restaurants.     

Food safety issues of high pressure processed fruit/vegetable juices

The food safety issues of the high pressure pasteurized fruit/vegetable juices are the focus of this paper. The development of Hazard analysis and critical control points system for production of carrot, red beet and apple/broccoli/orange juice is given together with results of analysis of samples, challenge testing and storage tests. The anti-mutagenic activity in vitro tests are also presented. Procedures have been established for the start-up of experimental production of mentioned juices for the Czech food market. The development of other types of juices based on cruciferous vegetables is mentioned. The aim of this work is to provide the Czech population with information on functional foods that act against chemical mutagens, limiting carcinogenesis.     

Permanence for non-autonomous food chain systems with delay

In this paper we first establish a new general criterion for the permanence of Kolmogorov-type systems of nonautonomous functional differential equations. Then, as applications of this criterion we study the permanence of a class of n-species general nonautonomous food chain systems with delay and new sufficient condition are established.     

New Aspects of the Maillard Reaction in Foods and in the Human Body

The reactions that occur during the cooking, baking, and preservation of foods of all kinds are of great importance for the production of aroma, taste, and color. However, more recently it has been shown that these reactions may be accompanied by a reduction in nutritive value and the formation of toxic compounds. For these reasons, the very complex reactions between reducing sugars and the free amino groups of amino acids or proteins, known as non-enzymatic browning or the Maillard reaction, have again caught the interest of chemists. The Maillard reaction came to be seen in a new light as it was realized that it actually occurred in the human body. As a general rule, the longer the half-life of a protein, the larger the amount of its Maillard products found, i.e., important factors are the ‘age’ or persistence of the protein in the body and the glucose concentration, particularly in diabetics. Many of the symptoms developed by diabetics resemble those of premature aging, which leads to the possibility that glucose, because of its reactivity towards proteins, is fundamentally involved in the normally slow progress of aging.     

Simultaneous determination of preservatives,sweeteners and antioxidants in foods by paired-ion liquid chromatography

Summary A paired-ion, reversed-phase high-performance liquid chromatographic method was developed for the simultaneous determination of sweeteners (dulcin, saccharin-Na and acesulfame-K), preservatives (sodium dehydroacetate, sorbic acid, salicyclic acid, benzoic acid, succinic acid, methyl-para-hydroxybenzoic acid, ethyl-para-hydroxybenzoic acid, n-propyl-para-hydroxybenzoic acid, isopropyl-para-hydroxybenzoic acid, n-butyl-para-hydroxybenzoic acid, and isobutyl-para-hydroxybenzoic acid), and antioxidants (3-tertiary-butyl-4-hydroxyanisole and tertiary-butyl-hydroquinone). A mobile phase of acetonitrile-50 mM aqueous α-hydroxyisobutyric acid solution (pH 4.5) (2.2 : 3.4 or 2.4 : 3.6, v/v) containing 2.5 mM hexadecyltrimethylammonium bromide and a C₁₈ column with a flow rate at 1.0 mL/min and detection at 233 nm were used. This method was found to be very reproducible with detection limits ranged from 0.15 to 3.00 μg. The retention factor (k) of each additive could be affected by concentrations of hexadecyltrimethylammonium bromide and α-hydroxyisobutyric acid, and pH and ratio of mobile phase. The presence of additives in some food samples was determined.     

冷原子荧光法测定食品中的汞

研究了断续流动进样冷原子荧光法测定食品中痕量汞，获得方法的检出限为0.02μg/L。     

6种化学计量学法同时分光光度测定5组分的比较研究及食品分析

优化了在表面活性剂存在下以肉桂基荧光酮同时测定铝、铜、锰、锌、钴的显色折衷条件；比较研究了偏最小二乘、岭回归、多元线性回归、多元逐步回归、目标因子分析和卡尔曼滤波法用于这一体系同时测定此５组分的优缺点，结果表明对于此类所含各组分吸收光谱重叠严重且吸光度加和性欠佳体系，上述６法中以偏最小二乘和岭回归法为最适宜；经用于九种人工合成液和四种食品分析，均获满意结果，分析两种茶叶结果也与ＩＣＰ－ＡＥＳ法一致     

Volatile flavoring substances in foodstuffs

The odor of most foods is produced by mixtures of many volatile flavoring substances. Over the past century, numerous food flavors have been analyzed in sufficient detail to allow a survey of the classes of substances responsible, the formation of individual flavoring substances, and their fixation in the foods. In addition to special biosynthetic pathways, the breakdown of fats and the Maillard reaction have been found to be particularly important to the formation of flavoring substances.     

Multi-residue pesticide analysis in fruits and vegetables by liquid chromatography-time-of-flight mass spectrometry

In this work, a new multi-residue methodology using liquid chromatography-time-of-flight mass spectrometry (LC-TOF-MS) for the quantitative (routine) analysis of 15 pesticide residues has been developed. The analytical performance of the method was evaluated for different types of fruit and vegetables: pepper, broccoli, tomato, orange, lemon, apple and melon. The accurate mass measurements were compared in different matrices at significantly different concentration levels (from 0.01 to 0.5 mg/kg) obtaining accuracy errors lower than 2 ppm, which is well within the accepted limits for elemental confirmation. Linearity of response over two orders of magnitude was demonstrated (r > 0.99). Matrix effects resulting in suppression or enhancement of the response were frequently observed, most notably in broccoli and citrus. Instrumental limits of detection (LOD) were between 0.0005 and 0.03 mg/kg depending on the commodity and pesticide studied, all being within European Union regulations for food monitoring program. Finally, the methodology was applied to the analysis of two samples from an inter-laboratory exercise. The high degree of confirmation for target pesticides by accurate mass measurements demonstrated the applicability of the method in routine analysis. This study is a valuable indicator of the potential of LC-TOF-MS for quantitative multi-residue analysis of pesticides in vegetables and fruits.     

Sample preparation including sol-gel immunoaffinity chromatography for determination of bisphenol A in canned beverages, fruits and vegetables

The paper describes the development of a very simple method to prepare samples of canned food (beverages, fruits and vegetables) for the determination of bisphenol A by isocratic HPLC with fluorescence detection. The new sample preparation method makes use of the selectivity of bisphenol A antibodies immobilized in a silica matrix by an inexpensive and simple sol-gel technique. In spite of applying highly complex food matrices, immunoaffinity columns could be used for clean-up of at least 15 real samples. Limits of detection (S/N=3) ranged from 0.1 ng/ml for beverages to 4.3 ng/g for vegetables.