IN VITRO STUDIES TO CONTROL THE GROWTH OF MICROORGANISMS OF SPOILAGE AND SAFETY CONCERN IN HIGH-MOISTURE, HIGH-pH BAKERY PRODUCTS

Initial agar plate studies were done to determine the effects of various levels (0 to 2,000 ppm) of potassium sorbate (KS) and sorbic hydroxamic acid (SHA) over a wide pH range (5 to 9) on the growth of microorganisms of spoilage and safety concern in high-moisture, high-pH bakery products. While growth of most microorganisms was inhibited for > 28 days on agar plates containing ∼1,000 ppm of KS at pH 5 and incubated at 30C, growth of all microorganisms occurred in plates at pH 7 and 9, regardless of the concentration of KS. SHA was equally effective at pH 5, however, it proved to be a more effective inhibitor against most microorganisms at higher pH (9).
Subsequent agar plate studies were done with water-ethanol (WE) and mastic oil-ethanol (ME) emitters. While WE emitters failed to control the growth of all microorganisms under investigation, ME emitters controlled the growth of most microorganisms, with the exception of Listeria monocytogenes, for ∼12 to 28 days on agar plates packaged in high-gas-barrier Cryovac or metallized bags, respectively. Inhibition was not simply due to the levels of ethanol, which ranged from ∼1.2 to 2.8% v/v, but rather, the mastic volatiles in the package headspace.
This study has demonstrated the potential of SHA and ME emitters to control the growth of several microorganisms of spoilage and safety concern in high-moisture, high-pH bakery products. However, the type of packaging material influenced the antimicrobial efficacy of this vapor-phase inhibitor.     

IN DAIRY PRODUCTS

The paper deals with the latest equipment available for the detection of both ferrous and non-ferrous metals in dairy products. The basic principle of the equipment is described and deals with both the metal detector, the conveyor and its associated automatic rejection system. A detection equipment which can sense the presence of ferrous metal in foil-wrapped goods is also described. A summary of the activity on the development of a foreign body detection using 'soft' X-rays is also dealt with, and the performance of the system on foreign bodies such as metal, glass and stone is quantified.     

MECHANICAL PROPERTIES OF AERATED CONFECTIONERY

Mechanical properties, including an extensional modulus, penetration modulus and cut force, of an aerated confectionery nougat were measured instrumentally as a function of nougat density in the range 0.66–1.12 g/mL. Despite the fact that the material was not a true cellular solid, the properties were adequately modeled by the expression C₁(ρ-ρ_c)ⁿ with n = 3 as befits a closed-cell foam. The critical density, ρ_c, appeared to correspond to the density at random close packing for spherical air cells, i.e., an air cell fraction of ≈ 0.6.     

OUTGROWTH OF CLOSTRIDIUM PERFRINGENS SPORES IN COOK-IN-BAG BEEF PRODUCTS1

Clostridium perfringens growth from a spore inoculum was investigated in vacuum-packaged, cook-in-bag ground beef that included 0.3% (w/w) sodium pyrophosphate, pH 5.5 or 7.0, and salt (sodium chloride) at 0 or 3% (w/w). The packages were processed to an internal temperature of 71.1C, ice chilled and stored at various temperatures. The total C. perfringens population was determined by plating diluted samples on tryptose-sulfite-cycloserine agar followed by anaerobic incubation for 48 h at 37C. At 28C, a combination of 3% salt and pH 5.5 was effective in delaying growth for 24 h. At 15C, growth occurred within 6 days in samples with pH 7.0, but was delayed until day 8 in the presence of 3% salt at pH 7.0. Vegetative cells were not observed even after 21 days 21 of storage at 15C in the presence 3% salt at pH 5.5. C. perfringens growth was not observed at 4C regardless of pH or salt levels. The D-values ranged from 23.33 min (3% salt, pH 7.0) to 13.99 min (3% salt, pH 5.5). Cyclic and static temperature abuse of refrigerated products for 12–15 h did not permit C. perfringens growth. However, temperature abuse of cook-in-bag beef products for periods longer than 15 h in the absence of salt led to growth of C. perfringens from a spore inoculum.     

GLASS TRANSITION AND TEXTURE IN A TYPICAL SPANISH CONFECTIONERY PRODUCT: XIXONA TURRON

The water sorption isotherm at 25C and glass transition temperature were determined in a typical Spanish confectionery product (Xixona turrón), as well as in the fat-free product. The samples were equilibrated at water activity levels from 0.113 to 0.755. The GAB and BET models were fitted to sorption data and the monolayer moisture contents were 2.8 and 6.0 (g of water/100 g of dried sample) for turrón and fat-free turrón, respectively. The sorption data indicate a lipid interaction with hydrophilic constituents. The analysis of the glass transition temperature (Tg) of the product as a function of its moisture content is used to determine the critical water content (CWC) at which the product becomes rubbery, at a determined temperature. From sorption isotherm at the same temperature (25C) we can also determine the critical water activity (CWA). The plasticizing effect of water in Xixona turrón can be modeled by the Gordon and Taylor equation. The fat also has a plasticizing effect, which is more obvious at low water content. A Texture Profile Analysis (TPA) was performed on samples with different moisture contents. Only samples with a moisture content lower than CWC showed fracturability, due to its glassy state. In the rubbery state hardness, gumminess and chewiness decrease when water content increases. Elasticity and cohesiveness increase in line with water content, more strongly for those moisture levels which are higher than BET monolayer value.     

INFLUENCE OF CHEWING AND SWALLOWING BEHAVIOR ON VOLATILE RELEASE IN TWO CONFECTIONERY SYSTEMS

Electromyography, electroglottography and turbine airflow technology were used to characterize the chewing, swallowing and breath flow profiles of 35 subjects during the consumption of two different (a gum Arabic‐ and carrageenan‐based) confectionery chews. Simultaneous volatile release measurements were obtained using atmospheric pressure chemical ionization mass spectrometry. Subgroups of subjects displaying different eating characteristics were identified for both products. Parameters accounting for the maximum variance (product 1, 42% and product 2, 52%) between the subgroups were chewing force, chewing rate, proportion of work and total number of chews. Volatile release measurements were significantly different between the subgroups from product 1. The impact of the different eating characteristics on volatile release from product 2 was less defined, and postulated to be a result of the contrasting textural properties. Manipulating in vivo breakdown of chewy confectionery products, by texture modification, may influence consumer's volatile release and subsequent flavor perception.     

DETERMINATION OF SYNTHETIC COLORANTS IN CONFECTIONERY AND INSTANT DRINK POWDERS CONSUMED IN TURKEY USING UV/VIS SPECTROPHOTOMETRY

One hundred and forty samples of Turkish confectionery and 96 instant drink powders marketed in Turkey, colored with a single colorant, were analyzed for colorants using both quantitative and qualitative UV/VIS spectrophotometer determinations. Six and five synthetic food colorants were determined in confectionery and instant drink powders, respectively. All the synthetic colorants determined in confectionery, except for Erythrosine, are permitted for use by the Turkish Food Codex and European Community (EC). The permitted colorant levels in 63 (43.7%) of 135 confectionery and in 35 (36.45%) of 96 instant drink powder samples were determined to be higher than the maximum tolerable limit in the Turkish Regulations. Continuous surveillance programs may be warranted to monitor regularly the level of colorant in confectionery and instant drink powder consumed, especially by children.     

REMOVING MICROORGANISMS IN FRESH APPLE JUICE BY BACTERIAL CENTRIFUGATION

SUMMARY— Bactofugation, a continuous centrifugal process of removing microorganisms from liquid foods, was applied at 9.000 g force to chilled and heated apple juice at a rate of 1,600gph. A reduction 99.8% in total bacterial count and 99.9% yeast-mold count of fresh apple juice processed at 7° was obtained. Bactofugating chilled apple juice was more effective than bactofugating apple juice heated to 54°C and presented certain operational advantages. Bactofugated, chilled apple juice retained the same flavor as untreated, fresh apple juice and remained fresh 22 days at 5°C, compared to about 5 days for the untreated apple juice. The simplicity of bactofugation, its relatively high put-through capacity and its effective reduction of microbial populations in fresh apple juice suggest that the process has potential application toward improving the keeping quality of this food.     

鞣制材料及成品革中甲醛的研究

甲醛通常是用于合成鞣剂制备的一种基本原材料。即使目前的工业生产过程采用电脑进行控制,但也可能在最终产品中含有甲醛。甲醛是一种对于人体或其他生物极具危害性的物质。因此,在一些强制性条文中明确规定了这种物质在成品革中的最大含量以及测定其存在所应参照的分析方法。然而皮革中甲醛含量的测定方法不能完全适用于鞣剂产品中甲醛含量的测定,实际上会有很多因其他物质的存在而产生的干扰因素。所以不可能把鞣剂材料中甲醛含量和成品革的甲醛含量之间进行比较。论文对以上这些因素的数据进行了研究,旨在降低鞣剂产品及其所生产皮革中的甲醛含量。     

PHYSICAL AND RHEOLOGICAL CHARACTERISATION OF A CONFECTIONERY PRODUCT

The mechanical and rheological properties of caramel have been measured in the context of a continuous extrusion forming operation, including a repetition of the processing route. The sensitivity of mechanical testing of samples to processing is borne out by the changes in microstructure, as observed using the scanning electron microscope, which also affect the velocity of transmitted ultrasound. The effect of repeated processing is also greater at a lower processing temperature.     

DETERMINATION OF CARBOXYMETHYLCELLULOSE IN FOOD PRODUCTS

SUMMARY –A method was developed to determine sodium carboxymethylcellulose (CMC) in food products containing three or more hydrocolloids after prior removal of interfering substances. Papain was used to digest the proteins; calcium chloride was added to precipitate algin and pectic acid and sulfated hydrocolloids were then precipitated by cetylpyridinium chloride (CPC) in the presence of 0.5M NaCl. Celite 535 or Hyflo Super Cel was added, the mixture filtered over Reeve angel No. 202 paper and the residue washed with 0.01% CPC-0.01M NaCl. The filtrate and washings were collected and diluted with distilled water to attain a final concentration of 0.2M NaCl at which concentration the CMC was precipitated selectively by CPC. The mixture was filtered over a Celite 535 or Hyflo Super Cel column and the residue washed with 0.5M Na₂SO₄ and then with 0.01% CPC-0.01M NaCl until the washings were negative to the phenol-H₂SO₄ reagent. Finally, the residue on the column was washed with hot 30% H₂SO₄ and the hydrolyzed CMC in the eluate determined by the 2,7-naphthalenediol test. Based on the amount added to mixtures, recoveries of 75–86% were obtained from milk and other highly complex and proteinaceous products, with a standard deviation of ± 0.58 mg, when 10 mg of CMC were added. The determination is critically dependent upon the degree of substitution (DS) of the CMC. As a consequence, the method cannot be applied with absolute certainty to unknown samples.