Janice Harte

The effect of X-ray irradiation on Salmonella inactivation and sensory quality of almonds and walnuts as a function of water activity.

The overall goal of this study was to develop a set of process design principles for low-energy X-ray irradiation of tree nuts. Almonds and walnuts were inoculated with Salmonella Enteritidis PT30 and Salmonella Tennessee, and conditioned to four different water activities (0.23, 0.45, 0.64, and 0.84 a(w)). Thereafter, the inoculated/conditioned samples were irradiated to achieve up to a 5-log reduction in Salmonella using a pilot scale low-energy X-ray food irradiator. Greater efficacy (D(10)-value: the dose required to eliminate 90% of the microbial population) for inactivating SE PT30 and S. Tennessee was seen on the surface of almonds (0.226-0.431 kGy) than on walnuts (0.474-0.930 kGy) at all water activities. Also, the efficacy did not change monotonically with water activity. Overall, no significant difference (P>0.05) in sensory characteristics was seen between non-irradiated almonds and those irradiated to achieve a 5 log reduction in Salmonella. However, irradiating walnuts to the dose corresponding to a 5 log reduction caused a perceivable change in flavor. Post-irradiation storage tests revealed that surviving bacterial counts did not change over 120 days, regardless of nut type, Salmonella serovar, and a(w). Therefore, low-energy X-ray irradiation technology appears to be a promising non-thermal pasteurization strategy for certain types of nuts.

Consumer acceptance of fresh blueberries in bio-based packages

BACKGROUND Instrumental analyses have shown that non-vented bio-based containers made from poly(lactic acid) (PLA) have the capability to enhance blueberry shelf life as compared with commercial vented petroleum-based clamshell containers. However, consumer preference has not been explored so far. In this study, two sensory evaluations, triangle and paired preference tests, were performed after storing fruit in both containers at 3 and 10 degrees C for 7 and 14 days. In addition, physicochemical analyses were performed after each tasting in order to correlate instrumental findings with consumer preference. RESULTS The results of the triangle test showed the capability of the consumer to differentiate (P < or = 0.001) between blueberries from different packages at both storage temperatures. A consumer preference for flavour, texture, external appearance and overall quality (P < or = 0.001) of blueberries packaged in PLA containers was observed in the paired comparison test. The instrumental analyses showed that blueberries in the PLA packages exhibited a weight loss below the limit for marketable life, a stable soluble solid content and titratable acidity and no fungal growth during storage. CONCLUSION Consumers distinguished between blueberries from different packages and preferred those packaged in the PLA containers. The instrumental analyses showed that the usable life of the berries was extended in the PLA containers. A correlation between consumer preference and instrumental evaluations was found.

Effects of extrusion cooking on the chemical composition and functional properties of dry common bean powders

The impact of extrusion cooking on the chemical composition and functional properties of bean powders from four common bean varieties was investigated. The raw bean powders were extruded under eight different conditions, and the extrudates were then dried and ground (particle size⩽0.5mm). Compared with corresponding non-extruded (raw) bean powders (particle size⩽0.5mm), the extrusion treatments did not substantially change the protein and starch contents of the bean powders and showed inconsistent effects on the sucrose, raffinose and stachyose contents. The extrusion cooking did cause complete starch gelatinization and protein denaturation of the bean powders and thus changed their pasting properties and solvent-retention capacities. The starch digestibilities of the cooked non-extruded and cooked extruded bean powders were comparable. The extruded bean powders displayed functional properties similar to those of two commercial bean powders.

Interactions between sanitizers and packaging gas compositions and their effects on the safety and quality of fresh-cut onions (Allium cepa L.).

Onions are one of the most widely utilized vegetables worldwide, with demand for fresh-cut onions steadily increasing. Due to heightened safety concerns and consumer demand, the implications of sanitizing and packaging on fresh-cut onion safety and quality need to be better understood. The objective of this study was to investigate the effect of produce sanitizers, in-package atmospheres, and their interactions on the growth of Salmonella Typhimurium, mesophilic aerobic bacteria, yeast and mold, and the physico-chemical quality of diced onions to determine the best sanitizer and in-package atmosphere combination for both safety and quality. Diced onions were inoculated or not with S. Typhimurium, sanitized in sodium hypochlorite, peroxyacetic acid, or liquid chlorine dioxide, and then packaged in either polylactic acid bags containing superatmospheric O2, elevated CO2/reduced O2, or air, or in polyethylene terephthalate snap-fit containers. Throughout 14 days of storage at 7 °C, packaged diced onions were assessed for their safety (S. Typhimurium), and quality (mesophilic aerobic bacteria, yeasts and molds, physico-chemical analyses, and descriptive and consumer acceptance sensory panels). While sanitizer affected (P<0.05) fewer parameters (S. Typhimurium, mesophiles, yeasts and molds, headspace CO2, weight loss, and pH), in-package atmosphere had a significant (P<0.05) effect on all parameters evaluated. Two-way interactions between sanitizer and atmosphere that affected S. Typhimurium and pH were identified whereas 3-way interactions (sanitizer, atmosphere and time) were only observed for headspace CO2. Sodium hypochlorite and elevated CO2/reduced O2 was the best sanitizer and in-package atmosphere combination for enhancing the safety and quality of packaged diced onions. In addition, this combination led to diced onions acceptable for purchase after 2 weeks of storage by trained and consumer panels.

Freshness maintenance of cherries ready for consumption using convenient, microperforated, bio‐based packaging

BACKGROUND Current consumer demand for high-quality ready-to-eat fresh fruit in convenient bio-based packaging was met utilizing sanitized stem-free sweet cherries and a polylactic acid (PLA) cup with a PLA peelable microperforated lid. The newly developed packaging system was compared with the petroleum-based macroperforated bag currently used for retail. RESULTS After 27 days of storage at 1 °C, the PLA package maintained the cherry firmness, compared with a 50% reduction of the controls. No fungal decay was detected in the cherries stored in PLA, while the controls were non-marketable after 21 days. The PLA package allowed minimal weight loss (0.8%), compared with a weight loss of approximately 16% in the controls. Differences in the cherry aroma, color, acidity, soluble solids content, pH and quality index were also caused by the packaging type. A consumer sensory evaluation showed that cherries stored in PLA packages were more acceptable than those of the controls for appearance, texture, flavor and overall acceptability. CONCLUSION The new package matched both the consumer demand for high-quality fresh fruit ready for consumption in convenient bio-based packaging and the extended fruit marketability and consumer satisfaction desired by industry.

Preliminary quantification of the permeability, solubility and diffusion coefficients of major aroma compounds present in herbs through various plastic packaging materials

BACKGROUND Aroma permeation through packaging material is an important factor when designing a package for food products. The masses of aroma compounds permeating through films over time were measured at 25 °C using a quasi-isostatic system. A model was proposed for estimating the permeability coefficients (P) of key aroma compounds present in fresh herbs (i.e. eucalyptol, estragole, linalool and citral) through major plastic films used by the food industry [i.e. low-density polyethylene (LDPE), polypropylene (PP), nylon (Nylon), polyethylene terephthalate (PET), metalised-polyethylene terephthalate (MPET) and poly(lactic acid) (PLA)]. Solubility coefficients (S) were estimated from the amount of aroma compound sorbed in the films. Diffusion coefficients (D) were estimated following from the relation P = D*S. RESULTS P and D for all four aroma compounds were highest in LDPE, except for eucalyptol, which P was slightly higher in PLA. The solubility coefficients and contact angles were highest in PLA suggesting the highest affinity of PLA to these aroma compounds. The theoretical solubility parameters were correlated with the solubility coefficients for estragole and citral, but not for eucalyptol and linalool. CONCLUSION The preliminary P, D and S of eucalyptol, estragole, linalool and citral through LDPE, PP, Nylon, PET, MPET and PLA can be useful in selecting the proper packaging material for preserving these specific aroma compounds in food products and can potentially be used for estimating the shelf life of food products based on aroma loss.

Physicochemical properties of whole fruit and sensory quality of fresh-cut apples pre-treated with 1-Methylcyclopropene (1-MCP)

Apple fruit quality is an important factor in minimally processed or fresh-cut slices. Ethylene action inhibitor, 1-methylcyclopropene (1-MCP) is used commercially to extend the shelf life of selected fruits, including apples. The present study was designed to assess the selected physiochemical properties of whole fruit and sensory attributes of fresh-cut slices from three 1-MCP treated apple cultivars (Jonagold, Empire, and Mutsu) that were stored for 3 months in air or 6, 9, and 12 months in controlled atmosphere. Apples and fresh-cut slices were evaluated for selected quality characteristics at 3-month intervals. Generally, the 1-MCP treatment resulted in firmer fruit and lower pH, whereas it had no or minimal effect on fruit skin color and total soluble solids. Titratable acidity values decreased in both control and 1-MCP treated apples, the only exception being 12-month controlled atmosphere stored apples that showed an increase. At each 3-month interval, fresh-cut slices (after 10-day storage at 4°C) were evaluated by a 9-member trained panel for “difference from control” on a 0–8 scoring scale; the results of these evaluations showed relatively small “difference from control” scores for the degree of browning, texture, and flavor. At the 9-month storage, a 114-member consumer panel evaluated the appearance, texture, flavor, and overall acceptability of fresh-cut slices on a 1–9 hedonic scale. Except for Jonagold slice flavor, slices from 1-MCP treated fruit exhibited similar or higher sensory scores. The overall acceptability scores were 6.78, 7.12, and 7.18 for slices from Jonagold, Empire, and Mutsu apples, respectively.

Inhibition of Listeria monocytogenes in full- and low-sodium frankfurters at 4, 7, or 10°C using spray-dried mixtures of organic acid salts.

In meat processing, powdered ingredients are preferred to liquids because of ease of handling, mixing, and storing. This study was conducted to assess Listeria monocytogenes inhibition and the physicochemical and organoleptic characteristics of frankfurters that were prepared with organic acid salts as spray-dried powders (sodium lactate-sodium acetate, sodium lactate-sodium acetate-sodium diacetate, and potassium acetate-potassium diacetate) or liquids (sodium lactate, sodium lactate-sodium diacetate, potassium lactate, and potassium lactate-sodium diacetate). Full-sodium (1.8% salt) and low-sodium (1.0% salt) frankfurters were prepared according to 10 and 5 different formulations (n = 3), respectively, and were dip inoculated with a six-strain cocktail of L. monocytogenes (∼4 log CFU/g). Populations of Listeria and mesophilic aerobic bacteria were quantified during storage at 4, 7, and 10°C for up to 90 days. Four powder and two liquid full-sodium formulations and one powder low-sodium formulation, all of which contained diacetate except for 1% sodium lactate-sodium acetate powder, completely inhibited Listeria growth at 4°C. However, Listeria grew in full-sodium formulations at 10°C and in low-sodium formulations at 7 and 10°C except for the formulation containing 0.8% potassium acetate-0.2% potassium diacetate powder. All formulations were similar in terms of water activity, cooking yield, moisture, and protein content. Sodium content and pH were affected by the concentrations of sodium and diacetate, respectively. Frankfurter appearance, texture, flavor, and overall acceptability were similar (P > 0.05) regardless of the formulation, except for flavor and overall acceptability of the low-sodium formulation containing potassium acetate-potassium diacetate. Based on these findings, cosprayed powders appear to be a viable alternative to current liquid inhibitors for control of Listeria in processed meats.