Effects of fat on the properties of halloumi cheese

Halloumi cheese was produced from 11 bovine milks with fat contents of 1.61–4.04%, giving a range of 32–53% fat in dry matter (FDM) in the cheeses. Starter culture and/or microparticulated whey protein (Simplesse ^® 100(E)) was also added to selected batches of milk. Hardness decreased with increasing FDM, with increase in moisture and with lower pH. On sensory evaluation, there was an increase in preference score with FDM ( R ²   = 0.8). Inclusion of microparticulated whey protein may have had a fat mimetic effect, as preference scores otherwise decreased with increasing protein levels ( R ² = 0.75).     

Optimization of ingredients and process conditions for the preparation of tandoori roti using response surface methodology

A model capable of predicting the product quality of tandoori roti has been developed using response surface methodology (RSM) and used to determine the optimum processing conditions. The overall sensory score, which is an indicator of blister size, colour, appearance, handfeel, texture, mouthfeel, taste and aroma, was used to assess the product quality in the preparation of tandoori roti. The optimum conditions which were attained for maximum sensory score (31.6) were: water level – 720mL kg⁻¹ flour (the corresponding farinograph consistency – 800 BU at lever position 1:1), salt level – 11g kg⁻¹ flour, mixing time – 3.7 min in a Hobart mixer at 58 r.p.m., baking time – 37 s, and baking temperature – 425°C.     

Optimization Process of Black Soybean Natto Using Response Surface Methodology

ABSTRACT:  Response surface methodology (RSM) was used to determine the optimum combinations of 3 factors, cooking time (40 to 120 min), inoculated bacteria populations (10¹ to 10⁹ cells/100 g), and fermentation time (12 to 36 h) for producing black soybean natto. All of the responses (hardness, viscosity, and trichloacetic acid-soluble nitrogen) were significantly affected by the 3 factors. Fermentation time was the most important factor affecting quality of black soybean natto. Optimum combinations were cooking time 110 min, inoculated bacteria populations 10² to 10⁴ cells/100 g, and fermentation time 30 to 33 h.     

Ionizing Radiation Effects on Starch as Shown by Staudinger Index and Differential Thermal Analysis

SUMMARY— Corn starch in the form of raw granules at commercial moisture was irradiated at two levels: 3 × 10⁵ and 6 × 10⁶ rad from a Co⁶⁰ source. The irradiated samples were completely dissolved in alkali, indicating there was no cross linking induced in the starch molecules by irradiation. Viscosity determinations of starch solution diluted with distilled water exhibited the ion charge effect generally observed in other macromolecules.
The Staudinger indices of unirradiated, irradiated at 3 × 10⁶ rad and 6 × 10⁶ rad were 42, 22 and 16 respectively, which were an indication of depolymerization of starch macromolecules with increasing irradiation. The differential thermal analysis of the three samples also showed the depolymerization of the polymer with irradiation.
It is suggested that these two simple techniques–the Staudinger index and D.T.A.–could be usefully employed to characterize small differences in starches.     

Rapid dye reduction tests for the determination of microbiological quality of meat

Rapid dye reduction tests have been developed to determine the quality of meat. Three chemical indicators, resazurin and two tetrazolium compounds, were used to correlate the microbial numbers and reduction times in meat samples. Twenty-five surface samples from sheep carcasses were subjected to each reduction test. Total viable counts given were obtained at 37°C. Resazurin reduction time was 90–120 min when the bacterial counts ranged from 1.5×10⁶ to 7.7×10⁶/cm². Samples showing bacterial counts between 1.5×10⁶ and 6.0×10⁶/cm² reduced tetrazolium (NBT) in 360–390 min whereas samples containing bacterial counts of 2.1×10⁶/cm² took 420–450 min to reduce iodophenyl nitrophenyl tetrazolium (INT) dye. Regression equations relating the number of organisms per cm² and reduction time were applied to predict the microbiological quality of meat samples from reduction time data. Among the three dyes, resazurin gave the lowest reduction time.     

OPTIMIZATION OF MANUFACTURE OF ALMOND PASTE COOKIES USING RESPONSE SURFACE METHODOLOGY

The response surface methodology (RSM) was used in the optimization of a modified recipe of almond paste cookies to pinpoint the best combination of the most important factors, in order to obtain an enhanced product with quality characteristics similar to the typical one. In this modified recipe, bamboo fiber and fructose were added as humectant and anticrystallizing agents to extend the shelf life of the cookies. Five quantitative controllable factors were selected for the experimental design: weight of bamboo fiber, fructose/saccharose ratio (F/S) and weight of egg white as ingredients, and baking time and temperature as process parameters. To assess the product quality, texture, moisture content and color were considered as dependent variables. The three second-order polynomial models obtained by RSM and the subsequent optimization step indicated that a formulation with 28.95 g of fiber, 252.5 g of egg white, an F/S equal to 0.1, baking time and temperature of 21.5 min and 185.5C, respectively, represents the best recipe to manufacture a new product with quality attributes very similar to the typical one and, in addition, with an extended shelf life.

PRACTICAL APPLICATIONS

The importance of this work arises from the possibility to obtain new formulations by the enhancement of original recipes of products with a very limited shelf life using a statistical and designed approach. The achieved results led to a higher quality of these products over time, without changing the most important characteristics related to consumer acceptance.     

RHEOLOGICAL AND CHEMICAL PROPERTIES OF MOZZARELLA CHEESE

Dynamic viscoelastic parameters and chemical properties of Mozzarella cheese produced using a "no-brine" cheese making method with 3 different cooking temperatures (38, 41, and 44C) were determined. Samples were stored for 3 weeks at 4C before dynamic mechanical analysis at 22C. G', G" and tan δ were 5.8 – 6.4 × 10⁵ dyne/cm², 1.9 – 2.1 × 10⁵ dyne/cm², and 0.33 – 0.35, respectively, at 1% strain and 10 rad/s. The percentage of intact α_s-casein and β-casein were 38–40% and 33–35% of total protein in the cheese, respectively. The range of cooking temperatures used in this experiment had little effect on dynamic viscoelastic properties or the amount of intact protein for the cheese.     

CHARACTERIZATION OF MODEL NITROSYLHEME PIGMENTS WITH VISIBLE, INFRARED AND 15N FOURIER TRANSFORM NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY

Synthetic pigments that model the organic-soluble pigment in heat-processed cured ham were characterized with infrared (IR) and ¹⁵N nuclear magnetic resonance (NMR) spectroscopy. The two pigments synthesized were ¹⁵N nitrosyl (protoporphyrinato- IX) iron (II), or Fe^II PP¹⁵ NO, and ¹⁵N dinitrosyl (protoporphyrinato-IX), or Fe^II PP(¹⁵NO)₂. An NMR spectrum was obtained only for the Fe^II PP¹⁵ NO. The NMR spectrum consisted of a single peak + 1.78 ppm from the Na¹⁵ NO³ and –6.8 from the CH₃NO₂ reference. The IR spectrum included a single NO symmetric stretch at 1801 cm⁻¹. The visible spectrum of Fe^II PPNO did not match the visible spectrum of ham extracts, while it did with FE^II PP(¹⁵NO)₂. An unequivocal structural assignment of Fe^II PP¹⁵ NO was made, but longer NMR runs may be necessary to obtain a spectrum and unequivocal structural assignment of Fe^II PP(¹⁵ NO)₂.     

Rheological and physical evaluation of jet‐cooked oat bran in low calorie cookies†

Different levels of shortening in cookies (10%, 20% and 30% by weight) were replaced with 20% jet‐cooked oat bran, also called Nutrim oat bran (OB), to prepare cookies with fewer calories. The cookies containing Nutrim OB were investigated in terms of rheological and physical properties and compared with a control. As more shortening was replaced with Nutrim OB, a decrease in the diameter and an increase in the height of cookies were observed. The increased moisture content from Nutrim OB caused a decrease in the dynamic viscoelastic properties of cookie dough. Squeezing flow method showed shear thinning behaviours in all cookie doughs. Also, the elongational viscosity of cookie dough decreased significantly with more replacement of shortening with Nutrim OB. The rheological properties of cookie dough during baking indicated that all of the samples had similar types of viscoelastic characteristics during baking. However, the cookies containing more Nutrim OB exhibited more elastic properties which resulted in a decreased cookie diameter. There was no significant difference in cookie hardness among samples with up to 20% shortening replacement but the cookies became lighter in colour as the Nutrim OB content was increased.     

RADIATION STERILIZATION OF SPICES FOR HOSPITAL FOOD SERVICES AND PATIENT CARE

A survey of the commercial spices used by food services in a typical hospital environment revealed high contamination with microorganisms, i.e., 10⁴ to 10⁷ counts per gram. The predominant microorganisms were as followed (in colony counts/gram): (1) heat-resistant bacterial spores in black pepper, 1 × 10⁷; thyme, 2 × 10⁶; anise, 7 × 10⁴; curry powder, 4 × 10⁵; poultry seasoning, 8 × 10⁴; pickling spice, cardamom, and cumin, 1.5–3 × 10⁴; (2) mixed populations of vegetative cells and bacterial spores in cumin, 1 × 10⁶; (3) molds in cream of tartar, 2 × 10⁴. Sterility of food may be important in a hospital setting, especially in the care of immunocompromised patients. To eliminate the organisms, we recommend radiation treatment, accompanied by appropriate microbiological quality control. On the basis of radiation survival data, the composite natural flora would be reduced to the level of "commercial sterility" (defined as less than 10 organisms per gram((Kiss 1982) by the following minimum radiation doses (in kGy): black pepper, 13; thyme, 13; cumin, 12; anise, 10; curry, 7.3; pickling spice, 7; poultry seasoning, 6; cardamom, 9.4; cream of tartar, 4. For practical purposes, two dose levels can be recommended for treatment of spices in the hospital environment, low = 6–10 kGy and high = 10–15 kGy.     

Reduction of Streptococcus thermophilus in a whey protein isolate by low moisture extrusion cooking without loss of functional properties

A whey protein isolate powder (WPI) (4–5% water) inoculated with 5x10⁵ viable Streptococcus thermophilus per g, was continuously processed in a twin screw extruder under the following conditions (barrel length = 500 or 1000 mm; screw profile = forward transport and compression elements; moisture content during extrusion = 4–5%; feed rate = 10 kg h^-1; barrel temperature ( T_b ) = 80–204°C; speed of screw rotation = 50 r.p.m.). The minimum residence time determined by pulse injection of erythrosin was 20–25 s (500 mm barrel) or 35–40 s (1000 mm barrel).
Reduction values of viable Streptococcus thermophilus of 10^4.2-fold (500 mm barrel, T_b = 143°C) or 10^4.9-fold (1000 mm barrel, T_b = 133°C) were obtained without any modification of protein solubility or gelling properties. WPI extruded at the highest barrel temperatures (182–204°C) underwent limited browning and reduction of protein solubility. Gel permeation and hydrophobic interaction chromatography of the soluble constituents did not show any aggregates of β-lactoglobulin or α-lactalbumin.
Gels prepared from control or extruded WPI ( T_b 143°C with a barrel length = 500 mm or T_b 133°C with a barrel length = 1000 mm) were identical, as judged by scanning electron microscopy and rheological evaluations.     

Halogen lamp–microwave combination baking of cookies

The effects of halogen lamp–microwave combination baking on the quality of cookies in terms of texture, color and spread ratio were studied. In addition, gelatinization and pasting properties of cookies baked in different ovens were assessed by using a Rapid Visco Analyzer. The hardness values of the cookies increased with increasing baking time and/or halogen power. The microwave power also contributed to cookie hardness. The lightness values of the cookies decreased, while the a* and E values increased linearly during baking at different halogen lamp and microwave powers. The spread ratio of conventionally baked cookies was significantly lower than that of the other cookies. Halogen lamp power, microwave power and baking time were found to have a significant effect on the spread ratio of the cookies. The moisture contents of the cookies decreased during baking as the halogen lamp and/or the microwave power level increased. The best baking condition in a halogen lamp–microwave combination oven to produce cookies having similar quality parameters as conventionally baked ones was baking at 70% halogen lamp and 20% microwave power levels for 5.5 min. The baking time of these cookies is half of that required in conventional baking.     

HYGIENIZATION OF INDIAN CHICKEN MEAT BY IONIZING RADIATION

Both fresh and frozen chicken meat were evaluated for microbiological status by screening for total bacterial counts and for the presence of pathogens like Enterobacteria , Bacillus cereus, coagulase positive Staphylococci and Salmonella spp. Most of the samples exhibited heavy bacterial contamination (1.2 × 10⁵ - 2.6 × 10⁶/g), mainly with Staphylococcus spp. (1.5 × 10⁴ - 2.8 × 10⁵/g). All the chicken samples also showed the presence of Salmonellae (3 × 10¹ - 2.1 × 10²/g). Among the different serotypes observed in chickens . S. typhimurium was common in fresh as well as frozen chicken. Radicidation at 2 kGy at cryogenic conditions (−40°C) was efficient in eliminating the natural pathogenic contamination of the poultry . Salmonella spp. viz. S. seftenberg and S. typhimurium differed in radiation sensitivity, the D₁₀ values in phosphate buffer (pH 7.2) being 0.25 kGy and 0.12 kGy, respectively. Chicken homogenate (10%) offered approximately 2-fold protection to these cells. Chicken samples artificially inoculated with a heavy inoculum (10⁸ cells/g) of these 2 serotypes required higher gamma radiation doses of 4–5 kGy. The findings suggested that a dose of 2 kGy is adequate for normally contaminated chicken samples, but for the heavily contaminated chicken a dose of 4–5 kGy, depending upon the predominating Salmonella serotype present, is required .     

The yeast flora of stored ready-to-use carrots and their role in spoilage

Spoilage of ready-to-use grated raw carrots packaged in polymeric films and stored at 10°C was investigated for involvement of yeasts. Cryptococcus albidus was only isolated during the first 3 days of storage, increasing to levels of 10⁵–10⁶g^-1. Candida lambica was more commonly isolated after 3–7 days of storage, and reached 10⁷–10⁸g^-1 after 12 days. Candida sake was present throughout storage, increasing from 10⁵–10⁶ after 3 days to 10⁷–10⁸ after 12 days. In some samples, Candida parapsilosis and Candida tropicalis were also isolated at levels similars to C. sake . All the yeasts isolated at the end of storage were fermentative species and their metabolism was characterized with a Warburg apparatus. Neither the number of yeasts nor the composition of the yeast flora were related to the deterioration of the product. Although Candida lambica inoculated on grated carrots caused spoilage after 12 days at 10°C, the high O₂ permeable film was most effective in reducing exudate.     

Composition, sensory quality and respiration during ripening and storage of edible wild mango (Irvingia gabonensis)

The effects of tree and room ripening and of storage at chill temperatures and at 26–29°C on the sensory quality, composition and respiration of edible wild mango fruits were investigated.
Fruits harvested at the mature green stage and ripened at 26–29°C were slightly preferred to tree-ripened fruits in colour and texture. Apart from a lower moisture content, room-ripened fruits were comparable in composition with tree-ripened fruits. During storage at 26–29°C, CO₂ production increased sharply from 22 ml kg^-1 h^-1 at the end of the first day, reaching a maximum of 91 ml kg^-1 on day 5 and declining thereafter; O₂ consumption followed a similar trend. The respiratory climacteric coincided with the onset of ripening. Fruits held at 12–15°C developed symptoms of chilling injury including pitting and black spots in mature green fruits, and brownish discoloration, pitting, surface scald, excessive softening and decay in ripe fruits.     

Effect of irradiation and modified atmosphere packaging on the microbiological safety of minced pork stored under temperature abuse conditions

The safety of irradiated pork packed in 25% CO₂:75% N₂ and stored at abuse temperature (10 or 15°C) was assessed by inoculation studies involving Salmonella typhimurium, Listeria monocytogenes, Escherichia coli, Yersinia enterocolitica and Clostridium perfringens . Irradiation to a dose of 1.75 kGy reduced pathogen numbers to below the detection limit of 10² cells g^-1. When higher inoculum levels were used (10⁶ cells g^-1) irradiation at 1.75 kGy reduced pathogen numbers by 1 –>5 log₁₀ cycles depending on strain. Clostridium perfringens was the most resistant, and Y. enterocolitica the most sensitive of the pathogens studied.
In all cases when high numbers (10⁶ to 10⁷g^-1) of spoilage and/or pathogenic bacteria were present initially on the pork the meat appeared spoiled, and although irradiation reduced the number of microorganisms, the meat was still unacceptable from a sensory viewpoint after treatment.
It was concluded that the microbiological safety of irradiated, modified atmosphere packaged (MAP) pork is better than that of unirradiated MAP pork.     

CHANGES IN SIZE OF GAS CELLS IN DOUGH AND BREAD DURING BREADMAKING AND CALCULATION OF CRITICAL SIZE OF GAS CELLS THAT EXPAND

Microscopic observation showed that a group of small air cells entrained during the early stage of mixing is the original cause of cell structure of bread. At the beginning of fermentation, about 3 × 10⁸/m² gas cells with diameters between 3 × 10⁻⁶ and 8 × 10⁻⁴ m were entrained in the dough. The distribution curve of cell size was approximately normal on a logarithmic scale. During fermentation and proofing, a great portion of carbon dioxide was released into cells larger than about 10⁻⁴ m in diameter that was equivalent to a few percentages of total number of gas cells. After baking, gas cells smaller than 10⁻⁴ m in diameter were not observed and the total number of cells in baked bread reduced to about 10⁶/m² with diameters between 10⁻⁴ and about 5 × 10⁻³ m. The critical cell size to expand generally agreed with the calculated value using an equation, rc'= 3s/E (re': critical radius to expand, s: surface tension, E: elasticity), and cited value of s and E.     

Water recycling in processing orange peel to a high dietary fibre powder

Water recyling in fruit and vegetable processing may contribute to decreasing industrial waste and load. Water was recycled for washing orange peel to prepare a high dietary fibre powder using tap water washing as the standard. Total sugar (12.1–13.1%), total dietary fibre (70–71.5%), soluble dietary fibre (21–22%), yield (59–60%), water holding capacity (7.8–8.1  g water g⁻¹ dry matter), colour and microbiological quality of a dry product were not significantly affected when the liquors from pulping and pressing were recycled for washing peel. Recycling liquors from pulping and pressing gave the highest energy (43%) and water (33.4%) savings, respectively.     

Colour loss during extrusion cooking of β-carotene-wheat flour mixes as an indicator of the intensity of thermal and oxidative processing

The thermal and/or oxidative colour loss from a wheat flour/all-trans β-carotene (20–80 mg kg⁻¹) mix during extrusion cooking follows first order kinetics. The intensity of processing in extrusion is reflected in the overall rate constant ( K ) of colour loss. K -values were in the range 3–20x10⁻³ s⁻¹. They increased markedly with decreasing water content of the mix (24–14%), and with increasing barrel temperature (100–220°C). Results were independent of the type of twin-screw extruder (Werner-Pfleiderer Continua 37 or Clextral BC-45). Modelling of the overall rate constant K and of the 'equivalent plug flow' residence time was used to define 'iso-destructive' extrusion conditions giving approximately the same residence time and the same mean product temperature. Extrusion under N₂ or O₂, or in the presence of 1 mg BHT per g of β-carotene, slightly affected colour loss. Adsorption chromatography on alumina indicated that within a barrel temperature range of 125–200°C, 38–73% of the initial all-trans β-carotene was destroyed, and that 2/3 to 1/2 of this loss corresponded to the formation of 9-cis plus 13-cis β-carotene isomers. The formation of smaller amounts of unknown β-carotene derivatives may be responsible for the colour loss.     

EFFECT OF HIGH HYDROSTATIC PRESSURE, GAMMA-IRRADIATION AND COMBINATION TREATMENTS ON THE MICROBIOLOGICAL QUALITY OF LAMB MEAT DURING CHILLED STORAGE

The effect of gamma irradiation (1.0 kGy) and high hydrostatic pressure (200 MPa for 30 min), either alone or in combination on the shelf-life of lamb mince meat at 0–3C was studied. Untreated control samples initially had total microbial counts of 10⁵ CFU/g, 10² CFU/g of coliforms and 10⁴ CFU/g of Staphylococcus spp. Coliforms were eliminated by all the treatments . Staphylococcus spp. however, were reduced only by 1 log cycle when treated with irradiation alone and high pressure alone. These species were a mixture of mannitol-fermenting and mannitol-nonfermenting strains. In samples subjected to the combination treatment , Staphylococcus spp. appeared only after 3 weeks of storage and all were mannitol-nonfermenting. On the basis of microbiological and sensory quality, the shelf-life of the control sample was less than 1 week. All treated meat samples had a shelf-life of 3 weeks, but only combination treated samples were free from potentially pathogenic Staphylococcus spp .