RELATIONSHIP BETWEEN FOODBORNE BACTERIAL PATHOGENS AND THE REACTIVE ARTHRITIDES

Certain individuals suffer complications after diarrheic episodes caused by Campylobacter, Salmonella, Shigella, or Yersinia. One of these complications may be a sterile arthritis such as reactive arthritis, Reiter's syndrome and anklylosing spondylitis. Reactive arthritis and Reiter's syndrome have been shown to have a bacterial etiology; however, such etiology, while suspected, has not been definitely confirmed for ankylosing spondylitis. These arthritides show a strong familial assocation and here, reactive arthritis, Reiter's syndrome and ankylosing spondylitis are characterized and the relationship of the diseases to the major histocompatility complex antigen, HLA-B27, is described. Studies have indicated that there may be molecular mimicry between certain microbial antigens and HLA-B27. Molecular mimicry is discussed in terms of its possible explanation of the etiology of the reactive arthritides. The roles of antibodies, lymphocytes, bacterial antigens, and stress proteins in the symptomology of the arthritides are reviewed .     

RELATIONSHIPS BETWEEN SOYBEAN COMPONENTS AND TOFU TEXTURE1

Tofu was prepared from samples of Amsoy 71 and Vinton or Vinton 81 soybeans grown in different environments. Relationships between soybean, soymilk and tofu protein, lipid, phytic acid, calcium, copper and iron were examined. All components except lipid in soybeans were significantly correlated with the same component in soymilk, but only phytic acid, copper and iron were significantly correlated in soybeans and tofu (moist basis). When relationships were examined on a dry basis, soybean and tofu protein were significantly correlated (r = 0.93). Soybean phytic acid was significantly correlated with tofu calcium (r = 0.90). Tofu calcium and hardness (r = 0.73) and springiness (r = 0.83). were significantly related, and tofu protein was significantly related to fracturability (r = 0.75). The higher-protein varieties (Vinton/Vinton 81) generally produced tofu that had a higher protein content and a firmer, more springy texture than that of the Amsoy 71 beans. Phytic acid may preferentially bind the calcium coagulant, altering the curd structure and the yield, composition and texture of the resulting tofu.     

AFLATOXIGENIC ASPERGILLI IN FOODS AND FEEDS IN UGANDA

Studies conducted during the sixties and the seventies on food crops in Uganda showed that the populace was exposed to consumption of aflatoxin-contaminated foods. These studies also linked the highest incidence of liver cancer in the world to the presence of high levels of aflatoxins in the food and beverages. After a lapse of a decade, it was of interest to investigate the occurrence of aflatoxins and aflatoxigenic fungi in staple Ugandan food crops and poultry feeds derived from these foodstuffs. A simple, rapid and reproducible procedure was used. The procedure consisted of growing or culturing feed grains on a selective medium, Aspergillus flavus/parasiticus agar (AFPA) followed by screening for aflatoxin producing fungi on a coconut agar medium (CAM) under UV light with a subsequent confirmatory screening method for aflatoxin production by the fungi in pure culture. Fifty-four samples consisting of corn and peanuts, soybean and poultry feed were analyzed for content of aflatoxigenic. A. flavus/parasiticus and 25 of the samples were also screened for aflatoxins B₁ and G₁, zearalenone, sterigmatocystin, ochratoxin A, citrinin, vomitoxin, and diacetoxyscirpenol (DAS). Aflatoxigenic A. flavus/parasiticus was detected from the majority of corn (77%), peanuts (36% human food and 83.3% animal feed) and poultry feed (66.6%). but not from soybean samples. Two samples out of 25 contained detectable levels of aJatosin B, (20 ppb). For the jirst time other mycotoxins, zearalenone (3 samples) and vomitoxin (2 samples) were detected in corn from Uganda.     

RELATIONSHIPS BETWEEN SENSORY CRISPNESS AND OTHER SENSORY AND INSTRUMENTAL PARAMETERS1

Twenty subjects judged the crispness, loudness, and firmness of sixteen food samples by both biting and chewing and by only biting the foods. These subjects also scored the foods for thirteen textural qualities. Instrumental measures of slope, peak force, and deformation to fracture were obtained for the sixteen foods from a snap test at four deformation rates. Whether a subject judged an attribute by the bite or the bite and chew technique made little or no difference in the sensory judgments. Crispness appeared to be very closely related to loudness and less closely related to firmness. Loudness of the chewing sounds was more closely related to crispness than to firmness. Of the sensory qualities studied, loud, snap, and crackly were the three most closely related to crispness. Of the instrumental parameters Young's Modulus generally had the highest correlation with the crispness of all foods and peak force generally had the highest correlation with firmness. Deformation rate had minimal effects on measures of flexure or peak force, but its effects on Young's Modulus were frequently large and irregular. A vibrotactile-acoustical hypothesis for crispness is proposed.     

RELATIONSHIPS BETWEEN BINDING QUALITY OF MEAT AND MYOFIBRILLAR PROTEINS

The binding quality of the heat set gel increased when F-actin was present in an appropriate ratio to myosin A. It increased further when tropomyosin was added to the myosin A/F-actin model system. The water holding capacity was increased by tropomyosin only. Thus, the contribution of not only myosin A but also of native tropomyosin and actin should be controlled in sausage manufacture. The presence of 0.6 M NaCl or KCl in the sol was necessary to produce high binding quality and high water holding capacity of heated myosin B gels. NaCl is preferred because of the taste effect on the meat product. Heating temperature (65, 80, or 90°CC) affected the physical properties of heated myosin B gels. The water holding capacity and the maximum relaxation time decreased with increasing temperature. In the manufacture of meat products, the heating temperature should be selected in accordance with the desired properties in the finished product.     

SIGNIFICANCE OF RESIDUAL ORGANISMS IN FOODS AFTER SUBSTERILIZING DOSES OF GAMMA RADIATION: A REVIEW1

The nature of the flora surviving substerilizing irradiation of foods is dependent on the dose applied and the conditions of applications as well as the microenvironment of the food. At a dose level low enough to preserve acceptable sensory properties of fresh food, few if any of the common contaminants of public health significance survive irradiation. Survivors are weakened and present no unique problem of acquired resistance through recycling. Those bacteria surviving a low dose treatment of a relatively contaminated product like ground beef can grow under normal storage conditions and cause obvious sensory spoilage. Thus, low dose irradiation extends the shelf-life of fresh foods and reduces public health hazards, but foods so treated require normal care in production and distribution.     

INDICATOR AND PATHOGENIC BACTERIA IN GUACAMOLE AND THEIR BEHAVIOR IN AVOCADO PULP

The presence of some indicator microorganisms and pathogenic bacteria in guacamole sampled from restaurants and street vendors, and the behavior of Salmonella spp. , Staphylococcus aureus, and Escherichia coli O157:H7 were studied in avocado pulp. Coliform, yeast and mold populations showed a wide dispersion, in agreement with the diversity of sanitary conditions observed among places sampled. The frequency of Salmonella spp. , Listeria monocytogenes, and E. coli were 1.3, 16.0, and 60.0 %, respectively; with higher numbers among street vendors. Populations of E. coli ranged from 29 to 3800 NMP/g and S. aureus from 2.95 to 5.35 log CFU/g. Thirteen out of 16 hemolytic L. monocytogenes strains were pathogenic for mice. In avocado pulp Salmonella spp. and E. coli O157:H7 showed a lag phase close to 3 h, and a generation time of 54 min and 1.23 h, respectively. No growth of pathogens was observed in avocado pulp stored at 4-7C.     

PERCEPTION AND MEASUREMENT OF STICKINESS IN SUGAR-RICH FOODS

The subject of stickiness is reviewed briefly in this paper, together with the factors influencing perceived stickiness in different contexts. A clear understanding of the difference between adhesive and cohesive failure mechanisms, and the factors influencing them, is a key requirement in developing successful tests to measure stickiness. This has led to the development of an instrumental test for measuring the stickiness of confectionery products, and recommendations are made for minimising sticking of confectionery products to surfaces.     

食品中伏马菌素的污染及污染控制

伏马菌素（Fumonisin）是20世纪80年代末期发现的一类由串珠镰刀菌产生的真菌毒素.伏马菌素分布广泛且毒性较大,因此它在食品安全中的意义越来越受到人们的重视.本文叙述了产伏马菌素的真菌,综述了中国不同地区、不同食品中伏马菌素污染的情况,以及各种降低伏马菌素污染的方法,综述了关于伏马菌素的立法.