The effect of packaging materials and oxygen on the colour stability of sliced bologna

The aim of the study was to determine the effect of packaging materials with different oxygen permeability, residual oxygen concentration in the package and light upon discoloration of the surface of sliced bologna. The packaging material caused significant differences in the discolouration of vacuum-packed, sliced bologna. The surface colour of sliced bologna packed in films with an oxygen transmission rate lower than 10cm³/m²/24h/atm was not affected by illuminated storage. Packages of sliced bologna with 0% oxygen in the head space showed good colour stability after 28 days of illuminated storage at 4 C. The discolouration of bologna was almost directly proportional to oxygen concentration in the package. Bologna stored in a high oxygen concentration developed more off-odour; 1% and 2% oxygen in the packages caused higher worst spot colour, discolouration and off-odour scores after 3 days of storage.     

Elimination of Listeria monocytogenes in soft and red smear cheeses by irradiation with low energy electrons

Soft and red smear cheeses are frequently contaminated by Listeria monocytogenes , sometimes at relatively high concentration (< 10⁵ CFUg^-1). This bacterium is radiosensitive (D₁₀ value of approximately 0.45 kGy) but irradiation of the whole cheese by X-rays induced off-flavours when the dose exceeded 1.0 kGy. Irradiation could be effective in eliminating L. monocytogenes only from lightly contaminated cheeses (> 10²CFU g^-1).
L. monocytogenes appears only in the rind (where the pH is greater than 6.3) and never grows in the core of the cheese. Under these conditions, a specific irradiation of the rind after ripening, with a low-energy electron beam at relatively high doses (up to 3.0 kGy), allows the total elimination of L. monocytogenes in heavily contaminated samples (10⁵-10⁶ CFU g^-1) without noticeable modifications of the organoleptic properties of the cheese.     

Analysis of Volatile Compounds from Strawberry Fruit Stored under Modified Atmosphere Packaging (MAP)

Volatile compounds were extracted from strawberries stored at 1°C for 10 days under modified atmosphere packaging (MAP) conditions in high barrier pouches flushed with either carbon dioxide, mixed gas, or air, and identified by gas chromatography/mass spectrometry. Canonical variate analysis based on 25 selected volatile compounds classified the samples according to treatment and/or quality level. Unpackaged samples, MAP samples treated with air or mixed gas kept in storage for 3 days, and strawberries evaluated at day 0 were all initially different from strawberries held in carbon dioxide. After 10 days storage, all MAP strawberries were classified close together and quality attribute scores were lower.     

Alcohol deterpenation of black pepper oil

The alcohol extraction of black pepper oil using three different oil to 60%-alcohol ratios was studied. Quantitative composition of the oils was established through their physical constants and gas-liquid chromatography. The 1:2 oil to 60% ethanol ratio showed the lowest oil recovery but resulted in sesquiterpeneless oil with the lowest terpene content and closest in sensory profile to the original oil.     

Production and Food Applications of the Red Pigments of Monascus ruber

Following our investigations on food additive production through fermentation, we studied properties of red pigments secreted by Monascus ruber in submerged culture, using ethanol and glutamate as carbon and nitrogen sources. After extraction and purification, these colorants were suspended in water for evaluation. The stability of the extract was tested both in solution and when incorporated into meat products (sausage and pâté). The pigments added to sausage or pate remained stable when stored for 3 mo at 4°C; their stability was between 92 and 98%. Sensory tests revealed that Monascus pigments could replace some traditional food additives such as nitrite salts or cochineal.     

Shelf Life of Sunflower Kernels

One raw and two oil roasted samples of sunflower kernels packaged in paper bags and in two types of low oxygen atmosphere pouches were stored at 5, 21 and 38°C. Quality of the stored samples was monitored by an expert sensory panel, peroxide, hexanal, free fatty acids and moisture determinations. Liking ratings, obtained with 99 consumers after 24 wk storage, were used to select end points for expert sensory ratings. The shelf life for roasted sunflower kernels was greater than 12 month when stored in nitrogen flushed pouches and as low as 8 wks when exposed to air at 38°C. Hexanal was a better index for shelf life of roasted sunflower kernels than was peroxide. The shelf life of raw sunflower kernels was > 12 month in packages providing some moisture but no oxygen protection.     

Characteristics and performance of some commercial shortenings

Six different brands of commercial shortenings were evaluated for their physicochemical characteristics and baking performance of cakes and biscuits (cookies). Three of the samples were locally made shortenings supplied by three different refineries (coded A, B and C), and the other three samples were imported shortenings obtained from supermarkets in Kuala Lumpur (D, E and F). Analyses and evaluations included slip melting point, solid fat content, fatty acid composition, triglyceride composition, creaming power and baking performance. All of the shortenings had slip melting points above 40°C. Sample A had the highest solid fat content at all temperatures. However, in terms of baking performance in cakes, sample C gave the highest volume, followed closely by samples B and A. Results indicated that the cakes were significantly different (P < 0.05) in terms of grain size and eating quality. Sensory evaluation on biscuits indicated that samples made with shortening D were preferred by a majority of the sensory panel, followed by those made with shortening C. The third, in order of panel preference, was biscuits made with shortening E.     

Uses of change-over designs and repeated measurements in sensory and consumer studies

The paper illustrates two statistical methods, the design and analysis of sensory experiments taking into account the effects of serving order and previously assessed treatment and the analysis of experiments with time repeated measurements.

Change-over design experiments balance both presentation order and carry-over effects. The proper analysis of variance allows the testing of these effects and the estimation of product means adjusted for carry-over effect.

Repeated measurements occur when groups are being compared over time. Either a corrected split-plot or a multivariate analysis of variance (MANOVA) with measurements at different times forming the variable should be adopted to allow proper tests for the time effect and for its interaction with the group effect.

The usefulness of change-over designs with an appropriate analysis and repeated measurement analysis will be demonstrated using sensory experiments involving trained assessors and consumers.