Industrial Applications of Selected JFS Articles

Food products are very complicated. Components react differently to various treatments, so the more complex the mixture, the more testing is required to predict how a process will affect the shelf-life, texture, and flavor of the food. As consumer preferences change, many of the rules of food safety vary. Some of these articles may provide starting information when working with complex ingredients.

Fresh Pineapple Safer with Radiation

In India, pineapple is frequently sold as peeled, cored fruit. Because refrigeration is scarce, the fruit is generally sold at room temperature. In the few studies of microbiological quality of minimally processed fruits and vegetables marketed in India, the quality was found to be poor, with the aerobic bacterial count and coliform counts (CCs) generally high and a large percentage of samples were contaminated with pathogens such as Listeria monocytogenes and Salmonella. Researchers from the Bhabha Atomic Research Centre, performed a study designed to (1) analyze the microbiological quality of minimally processed pineapple samples; (2) to determine the D10-value for S. Typhimurium inoculated in minimally processed (MP) pineapple; (3) to determine the radiation dose for 5-log elimination of S. Typhimurium from pineapple; (4) to study the survival and recovery of this pathogen in inoculated and radiation-treated pineapple samples, during storage at 4 and 8 °C; and (5) to study the microbial profile of both radiation-treated and untreated market pineapple samples during storage.

Despite the poor quality of the pineapple, from a bacteriological standpoint, the inoculation study showed that radiation processing of MP pineapple at 2 kGy dose was effective in eliminating viable spoilage microbial flora. This dose could eliminate 5 log CFU/g of S. Typhimurium from inoculated pineapple samples. Therefore, radiation processing at 2 kGy can ensure microbiological safety of MP pineapple. This dose does not affect the nutritional and organoleptic properties of MP pineapple when stored at 10 °C, according to the study. This suggests that heavily contaminated pineapple could be made safe by radiation processing. Use of contaminated pineapple would violate FDA rules; however, radiation could guard against contamination that occurred after the product was prepared for sale. p M98-101.

Improving Yogurt's Lactobacillus Content with Inulin

Lactobacillus acidophilus is a probiotic bacterium with several health benefits including improved immune system, reduction in occurrence of diarrhea in children and adults, lowered cholesterol contents and improved lactose intolerance. Some researchers have reported antitumor effects of consumption of foods containing L. acidophilus, and dietary supplements containing viable cells of L. acidophilus decreased β-glucuronidase, azoreductase, and nitroreductase, a group of enzymes which catalyze conversion of procarcinogens to carcinogens. While yogurt is considered a good carrier for lactobacillus, a way of increasing the number of organisms in yogurt was studied by researchers from Louisiana State and Melborne Univ.

The researchers chose to fortify the yogurt with inulin, an ingredient found in varying sizes. Inulin is a prebiotic food carbohydrate that increases the activity of Lactobacillus acidophilus, increases calcium absorption, and is a good source of dietary fiber. The objective was to determine the effect of short, medium, and long chain inulins on the characteristics of fat-free plain yogurt containing L. acidophilus. Inulins of short (P95), medium (GR), and long (HP) chain lengths were incorporated at 1.5% w/w of the yogurt mix. Viscosity, pH, syneresis, sensory properties (flavor, body and texture, and appearance and color), L. acidophilus counts, and color (L*, a*, and b*) of yogurts were determined at 1, 11, and 22 d after yogurt manufacture. The P95 containing yogurt had a significantly lower pH than the remaining yogurt, higher flavor scores than the yogurt-containing HP, and comparable flavor scores with the control. The yogurts containing HP had less syneresis than the control and a better body and texture than the remaining yogurts. Yogurts containing prebiotics of different chain lengths had comparable L. acidophilus counts with each other but higher counts than the control. However, inulins of various chain lengths did not affect viscosity, color, and product appearance. Chain length of prebiotics affected some quality attributes of probiotic yogurts. Prebiotic inulin with the smallest chain length (P95) resulted in lower pH of the product and increased syneresis compared to inulins of medium (GR) and long (HP) chain length. L. acidophilus counts were higher with the use of prebiotics compared to control. Chain length of prebiotics did not affect color or viscosity of fat-free yogurts containing L. acidophilus.p M79-84.

Combination Heat Systems Can Produce Preferable, Safe Products

Low acid food products require careful processing to insure safety. Aseptic processing combined with continuous flow microwave heating can provide the good effects of an aseptic process with the speed of microwave heating. Researchers from North Carolina State Univ. measured the dielectric properties of 2 different brands of salsa con queso to determine the advantages of processing these foods in such a way at a temperature range of 20 to 130 °C and charge of 915 MHz. Dielectric constant ranged from 58.7 at 20 °C to 41.3 at 130 °C with dielectric loss factor ranging from 41.0 at °C to 145.5 at 130 °C. The loss tangent at 915MHz ranged from 0.61 at 20 °C to 3.52 at 130 °C. The temperature profiles at the outlet during processing of salsa con queso in a 5-kW microwave unit showed a narrow temperature distribution between the center and the wall of the tube. The study showed that salsa con queso could be properly processed using a continuous flow microwave system. Further research is required to biologically validate such a process as the final step in establishing an aseptic process for salsa con queso using a continuous flow microwave system. p E121-124.

Protein Study Aids Approval of Chitosan?

Surimi, that popular food made from stabilized myofibrillar protein obtained from mechanically deboned fish flesh and washed with water, then blended with cryoprotectants, produces a quantity of wash water with protein content high enough to be an environmental pollutant. According to researchers from Oregon State Univ., surimi wash water (SWW) contains 0.5 to 2.3% protein, requiring a new technology to recover it economically. Recovery of SWW proteins (SWWP) would reduce environmental pollution, generate a high-protein ingredient that could be used for food or feed, and facilitate the reuse of process water in the plant.

The research team decided to try chitosan, known to be an effective coagulating agent to remove suspended solids from food processing effluents such as cheese whey, poultry wastes, and various other useful solids that ride wash water to a destination that isn't optimum. Chitosan can complex with polyanions including alginate, pectin, carrageenan, and other ingredients. To determine whether chitosan-protein complexes can be used as recovered proteins, rat feeding tests were completed, using 0.126 percent chitosan plus surimi protein. The preliminary study indicates that SWP as shown to be superior to most of the commonly used proteins, especially regarding protein concentration and essential amino acid composition. Total substitution by WWP in diets allowed the animals to gain weight normally and experience food feed conversion in a normal manner. The protein had good modified PER, and the animals had healthy liver and kidney tissues, and normal blood chemistry. Further studies based on microbial safety and chemical score will be needed to support efforts to obtain the approval for the use of chitosan-containing proteins in formulated foods. p S179-184.

Hibiscus seed oil evaluated

The hibiscus flower, also called roselle, produces four kidney shaped, brown seed capsules that are particularly rich in various tocopherol compounds. The plant is used in Chinese herbal medicine, is fairly easily grown, and currently being used in tea infusions. The paper “Roselle (Hibiscus sabdariffa) Seed Oil is a Rich Source of γ-Tocopherol” reports the results of work by a group of Spanish researchers in characterizing the compounds, and lists the methods that were used. Roselle (Hibiscus sabdariffa) could be used as a source of strong water-, lipid soluble antioxidants, including vitamin E. The seeds of roselle, that currently have no economic application, are a source of a vegetable oil that is low-cholesterol and rich in other phytosterols and tocopherols, particularly β-sistosterol, and γ-tocopherol. The global characteristics of roselle seed oil allow important industrial applications for this oil. These characteristics represent an added value for the culture of this plant, presently grown as a decorative shrub, and a windbreak. p S207-211.