Effect of temperature, pressure and calcium soaking pre-treatments and pressure shift freezing on the texture and texture evolution of frozen green bell peppers (Capsicum annuum)

The firmness of green bell pepper (Capsicum annuum) was studied under different processing conditions. Thermal texture degradation kinetics of pepper tissue between 75 and 95 °C could be accurately described by a fractional conversion model. The firmness of pre-processed pepper increased when the samples were submitted to several heat, pressure, and combinations of heat/pressure and calcium soaking pre-treatments. Pre-heating at 55 °C during 60 min and mild heat/high-pressure treatments (200 MPa at 25 °C, 15 min) yielded the best results, which were further improved when combined with calcium soaking. These pre-treatments significantly slowed down thermal texture degradation of pepper at 90 °C, a typical temperature used for pepper blanching prior to freezing. The above-mentioned pre-treated samples showed a significant reduction in firmness when frozen by regular freezing at 0.1 MPa. The same samples showed no changes in firmness when frozen by high-pressure shift freezing at 200 MPa. When freezing was carried out by high-pressure shift and after frozen storage (−18 °C) for 2.5 months, pressure pre-treated pepper showed a better retention of texture than thermal pre-treated pepper.     

Effect of heat treatment and individual shrink packaging on quality and nutritional value of bell pepper stored at suboptimal temperature

The goal of this study was to develop a technology for prolonged storage of pepper fruit at low temperature, based on physical treatments and packaging materials. Physical and compositional changes of red bell pepper fruit (Capsicum annuum L. cv.’Selika’) were monitored during 21 days of cold storage (at 2 °C) plus 3 days at 20 °C (market simulation). Fruits were treated with tap and hot water and stored without packaging or sealing each fruit in individual shrink packaging (Cryovac®). This research revealed that individual shrink packaging following prestorage with hot water rinse (55 °C for 15 s) over brushes, significantly reduced weight loss, softening, decay incidence and chilling injury, while maintaining a quality. The wrapped fruit ripened normally (carotenoid content increased) during shelf‐life period, when shifted to 20 °C after unwrapping. This study showed that antioxidant levels of pepper fruit may be preserved during storage.     

The dehydration of paprika with ambient and heated air and the kinetics of colour degradation during storage

The hygroscopic behaviour of dried red pepper is characterized by means of water vapour adsorption isotherms at 5, 20 and 35°C; from the GAB equation, a monolayer water content of 0·0816 kg H₂O per kg dry matter has been deduced. The effect of temperature on the drying rate of pepper is considered and yields are compared when the drying is carried out with ambient air and with different loading densities (10–40 kg m⁻²). The kinetics of paprika colour degradation during storage at different temperatures and with a moisture content corresponding to the monolayer have been studied. A sharp change in the rate of colour loss is observed at 15°C: the value Q₁₀ (°C) changes from 1·62 to 2·82 when the temperature rises above 15°C.     

辣椒籽油的制备及其挥发性香味物质的研究

利用亚临界低温萃取技术对经过炒制前处理的辣椒籽进行萃取制备得到辣椒籽油,并采用同时蒸馏结合GC-MS法,分析了不同的炒制温度(120~200℃)和炒制时间(5~25 min)对辣椒籽油中的挥发性成分和脂肪酸成分的影响。在炒制时间为5 min,炒制温度低于140℃时,芳樟醇、月桂烯、双戊烯是辣椒籽油的主要香气物质,当温度高于140℃时,吡嗪类化合物和2-戊基呋喃是辣椒籽油的主要香气物质。在炒制温度为140℃,炒制时间为5 min时,辣椒籽油中的芳樟醇、月桂烯、双戊烯的含量分别达到最大值,随着炒制时间的增加,辣椒籽油中的2,3,5,6-甲基四吡嗪和2-戊基呋喃的含量在20 min时达到了最大值。辣椒籽油中主要的脂肪酸成分是棕榈酸(11.57%)、油酸(76.16%)和亚油酸(7.14%)。     

Structural and physical properties of dried Anaheim chilli peppers modified by low‐temperature blanching

The effect of low‐temperature blanching and drying processes on the ultrastructural and physical properties of Anaheim chilli pepper was studied and optimum conditions to provide a final product with maximum firmness were determined. Lots of Anaheim pepper were blanched in water for 4 min at 48, 55, 65, 75 and 82 °C and maintained for hold times of 35, 45, 60, 75 and 85 min, blanched again for 4 min at 96 °C and dehydrated at 53, 60, 70, 80 and 87 °C. After treatment the samples were rehydrated in water at 30 °C. Rehydration ratio, texture and structural changes were evaluated. Optimisation used a second‐order rotatable central composite design. Texture and rehydration ratio were affected by blanching temperature and the interaction of blanching temperature with hold time (p ≤ 0.05); drying temperature did not show a significant effect. The best results, ie those which gave greatest firmness, were obtained by blanching at 64 °C for 4 min, holding for 55 min after blanching, followed by a second blanching at 96 °C for 4 min and then drying at 70 °C. Evaluation of the rehydrated dried pepper by microscopy showed that low‐temperature blanching close to the optimum conditions provided a protective effect in maintaining cell wall integrity. The results of processing increased firmness in the rehydrated product by a factor of 1.97. Copyright © 2003 Society of Chemical Industry     

Effect of Heat Treatment for Trypsin Inhibitor Inactivation on Physical and Functional Properties of Peanut Protein

Trypsin inhibitor (TI) inactivation in whole peanut kernels exposed to moist heat had a decimal reduction time (D) of 91 min at 100°C and 9.3 min at 120°C. When all processing times were converted to process time at 120°C using Z of 20°C, the composite D at 120°C was 10 min. Solubility decreased with heating to reach a minimum with 98% TI inactivation. Capacities to spontaneously absorb water and to gel were retained better on heating at 120°C than at 100°C for equal TI inactivation. The most functional protein was in kernels heated at 120°C for 10 min. When 20 or 30% meat protein in a meat loaf formulation was replaced with the latter peanut protein, the resulting loaf retained more fat and water and exhibited higher shearing strengths than all meat formulations.     

Desorption Isotherms of Some Vegetables

The desorption isotherms of potato, carrot, tomato and green pepper were determined at 30, 40, 50 and 60°C and within the range of 10–90% water activity. Iglesias and Chirife, Halsey and GAB equations were tested to fit the experimental data. The net isosteric heat of desorption of water was determined from the equilibrium desorption data.     

Ripening characterisation and decay development of stored apples after a short pre-storage hot water rinsing and brushing

Two different heat treatments were compared as to their efficacy in preventing decay and maintaining post-harvest quality of Golden Delicious (Malus domestica Borkh). The apples were treated with a hot water rinsing and brushing machine (HWRB) for different temperatures, and compared to apples given a dry heat treatment (96 h at 38°C) and untreated apples. HWRB at 55°C for 15 s significantly reduced (at P=0.05) decay development in Penicillium expansum-inoculated fruit after 4 weeks at 20°C, or in naturally infected fruit after prolonged storage of 4 months at 1°C plus 10 days at 20°C. This treatment inhibited ripening processes as measured by relatively low respiration rate and ethylene evolution and a slow colour development, compared with non-heated control, and fruit quality was maintained. Heat damage was observed on fruit rinsed and brushed at 60 or 65°C for 15 s. Although similar results were obtained in decay control and fruit quality of HWRB-55°C treated fruit and dry heated fruit, the commercial application of this short pre-storage heat treatment is more feasible than the dry heat treatment.     

Inactivation of peroxidase and lipoxygenase in carrots, green beans, and green peas by combination of high hydrostatic pressure and mild heat treatment

The efficiency of high hydrostatic pressure (HHP) with the combination of mild heat treatment on peroxidase (POD) and lipoxygenase (LOX) inactivation in carrots, green beans, and green peas was investigated. In the first part of the study, the samples were pressurized under 250–450 MPa at 20–50 °C for 15–60 min. In the second part, two steps treatments were performed as water blanching at 40–70 °C for 15 and 30 min after pressurization at 250 MPa and 20 °C for 15–60 min. Carrot POD was decreased to 16% residual activity within the first 30 min at a treatment condition of 350 MPa and 20 °C and then it decreased to 9% at 60 min. When the carrots were water blanched at 50 °C for 30 min after HHP treatment of 250 MPa at 20 °C for 15 min, 13% residual POD activity was obtained. For green beans, the most effective results were obtained by two steps treatment and approximately 25% residual POD activity was obtained by water blanching at 50 °C for 15 min after pressurization at 250 MPa and 20 °C for 60 min. An effective inactivation of POD in green peas was not obtained. For carrots, LOX activity could not be measured due to very low LOX activity or the presence of strong antioxidants such as carotenoids. After pressurization at 250 MPa and 20 °C for 15 or 30 min, water blanching at 60 °C for 30 min provided 2–3% residual LOX activity in green beans. The treatment of 250 MPa for 30 min and then water blanching at 50 °C for 30 min provided 70% LOX inactivation in green peas.     

Use of UV-C treatments to maintain quality and extend the shelf life of green fresh-cut bell pepper (Capsicum annuum L.)

Abstract: The objective of this work was to select a Ultraviolet‐C (UV‐C) treatment for fresh‐cut mature green bell pepper, and to evaluate the effect of its combination with refrigeration on quality maintenance. Bell pepper sticks were treated with 0, 3, 10, or 20 kJ/m² UV‐C in the outer (O), inner (I), or both sides of the pericarp (I/O) and stored for 8 d at 10 °C. During the first 5 d of storage, all UV‐C treatments reduced deterioration as compared to the control. The treatment with 20 kJ/m² I/O was the most effective to reduce deterioration, and was used for further evaluations. In a second group of experiments, mature green bell pepper sticks were treated with 20 kJ/m² I/O, stored at 5 °C for 7 or 12 d and assessed for physical and chemical analysis, and microbiological quality. UV‐C‐treated fruit showed lower exudates and shriveling than the control. UV exposure also reduced decay, tissue damage, and electrolyte leakage. After 12 d at 5 °C, UV‐C irradiated peppers remained firmer and had higher resistance to deformation than the control. The UV‐C treatments also reduced weight loss and pectin solubilization. UV‐C exposure decreased the counts of mesophile bacteria and molds, and did not affect acidity or sugars. UV‐C‐treated fruit stored for 0 or 7 d at 5 °C did not show major differences in antioxidants from the control as measured against DPPH^? or ABTS^?+ radicals. Results suggest that UV‐C exposure is useful to maintain quality of refrigerated fresh‐cut green pepper. Practical Application: Exposure to UV‐C radiation before packing and refrigeration could be a useful nonchemical alternative to maintain quality and reduce postharvest losses in the fresh‐cut industry.     

Gelatinization and Liquefaction of Starch with a Heat Stable α-Amylase

Sweet potato and corn starches were gelatinized and liquefied to dextrose equivalent (DE) 10 in a steam-jacketed kettle or in a twin-screw extrusion cooker in a single step process with a heat stable ex-amylase. The time required to gelatinize and liquefy 20% starch slurries in a kettle at 95°C was 45 to 50 sec. Starch powder (10 kg/hr) and water (2-6 kg/hr) were fed to an extrusion cooker to adjust the moisture contents of the starch from 20 to 55% (wet basis) and gelatinized and liquefied to DE 10 at a barrel temperature of 120°C or above with 2 to 3% (w/w) a-amylase added. The optimum conditions for the operation were to feed starch with water to maintain 50% moisture and 2% heat stable a-amylase at a barrel temperature of 120°C.     

Moisture Sorption Characteristics of Kudzu Starch and Sweet Potato Starch

Moisture sorption characteristics of kudzu starch and sweet potato starch were investigated based on the results of moisture sorption isotherms at 11°C, 20°C and 30°C, thermal analysis, isosteric heat of sorption and entropy of sorption. The water of crystallization in sweet potato starch was strongly retained compared with that in kudzu starch. Differences in amount of moisture sorbed between kudzu starch and sweet potato starch seemed to be attributable to the stability of the microscopic structure. The interaction of moisture-sweet potato starch was stronger than that of moisture-kudzu starch. Amount of moisture sorbed and strength of moisture-starch binding of the starches, preheated to 110°C, decreased compared with those of the starches vacuum-dried at 20°C because of release of water from the amorphous part of the starch granule.     

Effect of heat treatment and evaporation on patulin and some other properties of apple juice

Patulin, hydroxymethylfurfural (HMF), colour and clarity values of 20 apple juice samples with different Brix contents were determined after heat treatment (90 and 100 °C for 5, 10, 15 and 20 min under atmospheric pressure) and evaporation (70 and 80 °C for 5, 10, 15 and 20 min) processes. As the heating and evaporation times increased, the concentration of patulin in the apple juice samples decreased. The 90 and 100 °C heat treatments resulted in reductions in patulin concentration of 18.81 and 25.99% respectively after 20 min; the corresponding values were 9.40 and 14.06% for 70 and 80 °C evaporation respectively. The increase in HMF was higher with heat treatment than with evaporation. Evaporation decreased the colour values of the samples, whereas heat treatment increased them. © 2003 Society of Chemical Industry     

Changes in appearance and natural microflora on iceberg lettuce treated in warm,chlorinated water and then stored at refrigeration temperature

The objective of this study was to determine the effect of warm, chlorinated water on the survival and subsequent growth of naturally occurring microorganisms and visual quality of fresh-cut iceberg lettuce. After dipping cut lettuce leaves in water containing 20 mg l⁻¹free chlorine for 90 s at 50°C, samples were stored at 5 or 15°C for up to 18 or 7 days, respectively. Populations of aerobic mesophiles, psychrotrophs, Enterobacteriaceae, lactic acid bacteria, and yeasts and molds were determined. The visual appearance and development of brown discoloration were monitored. Treatment of lettuce in warm (50°C) chlorinated water delayed browning of lettuce. Shelf life of lettuce stored at 5°C, as determined by subjective evaluation of color and general appearance, was about 5 days longer than that of lettuce stored at 15°C. Treatment in warm (50°) water, with or without 20 mg l⁻¹chlorine, and in chlorinated water at 20°C significantly (α= 0·05) reduced the initial population of mesophilic aerobic microflora by 1·73–1·96 log₁₀cfu g⁻¹. Populations increased, regardless of treatment, as storage time at 5°C and 15°C increased. The same trends were observed in populations of psychrotrophs and Enterobacteriaceae. Yeast populations increased slightly in lettuce stored at 5°C but were consistently about 3 logs lower than mesophilic aerobes. Populations of molds and lactic acid bacteria were less than 2 log₁₀cfu g⁻¹throughout storage at 5 or 15°C. Results suggest that heat (50°C) treatment may have delayed browning and reduced initial populations of some groups of micro-organisms naturally occurring on iceberg lettuce, but enhanced microbial growth during subsequent storage.     

Effects of Processing Treatments on Recovery of Capsaicin in Jalapeno Peppers

Capsaicin content in frozen, cooked and canned jalapeno peppers was quantified using GLC analysis and compared to the capsaicin content in raw peper. The frozen peppers were blanched for 3 min and stored at -18°C; canned peppers were blanched for 3 min and processed at 100°C for 50 min; cooked peppers boiled at 100°C for 10 min. Results demonstrated a significant difference (a = 0.05) between each treatment and the raw pepper. Frozen and canned peppers retained approximately one-half of the capsaicinoid compounds that were present in raw pepper.     

The effect of a natural antioxidant on the stability of heat-treated paprika

The colour loss occurring in a paprika made from the dehydrated fruits of pepper, Capsicum annuum L. var. Ocal (control), was compared with the colour lost by a similar paprika submitted to an industrial sanitation process involving water vapour. The heat treatment resulted in a considerable greater loss of colour when the paprika was stored at 25 °C in different relative humidities (0, 23, 57 and 75%) compared with the control paprika. The study also analysed the effect of adding a natural antioxidant (rosemary extract at 1%) to the heat‐treated product. In this case, colour stability increased significantly in all the conditions assayed; the lower the humidity, the greater the increase in stability.     

Effect of dry heat stabilisation on the functional properties of rice bran proteins

Rice bran was stabilised by dry heat method at 120 °C for 10–60 min, and then, protein was extracted from stabilised rice bran using weak alkali method. The storage characteristics of stabilised rice bran and the influences of dry heat pretreatment on the physicochemical properties of rice bran protein isolate were also evaluated. The results indicated that dry heat pretreatment could not only prevent rancidity of rice bran effectively, but also improve some functional properties of rice bran proteins, such as emulsifying properties, oil holding capacity, and water holding capacity. However, foaming properties and protein solubility were slightly destroyed because of heating. Rice bran was pretreated at 120 °C for 10 or 20 min and then extracted at pH 9.5, and the protein yields were 50.09% and 46.98%, respectively. Therefore, the dry heat treatment at 120 °C for 10 or 20 min was a suitable alternative process in stabilisation of rice bran.     

Alteration of Talaromyces flavus Heat Resistance by Growth Conditions and Heating Medium Composition

A strain of Talaromyces flavus var. macrosporus (NRRL 13641) was isolated from spoiled fruit drink and identified. It had a heat resistance (l/k) (death rate constant or decimal reduction time) of 191 min at 80°C and 6 min at 90°C with a calculated z of 6.7°C. Several strains of T. flavus were tested to determine the effects on heat resistance of environmental conditions such as pH, organic acids, brix, and type of medium. Heat resistance increased with increased brix in the heating medium. Growth on solid medium compared with liquid medium resulted in greater heat resistance. Growth at 20°C and 35°C produced ascospores with higher heat resistance than growth at 25°C while those produced at 30°C had intermediate heat resistance. Five cultures differed significantly in heat resistance.     

Ascorbic Acid and Folic Acid Content and Sensory Characteristics of Dehydrated Green Peppers

Moisture content, water activity, ascorbic and folic acid content, and color of blanched and unblanched green peppers, dried for 8 or 9 hr at 60°C or 12 hr at 49°C, were determined before and after 8 wk storage at room temperature. Sensory characteristics of the peppers were evaluated after storage. Blanching influenced ascorbic acid content, color, firmness, and intensity of green pepper, sweet and bitter flavor. Time and temperature of drying influenced water activity and some texture attributes.     

Identification of microbial hazards,methods for their control and critical control points for black pudding (‘boudin noir’)

Hazard analyses of black pudding (`boudin noir') preparation practices were conducted in four operations at an abattoir in Trinidad. The analyses consisted of watching all steps of preparation of the product on three occasions by each of the four processors, taking samples of ingredients and mixtures used during the steps to culture for common food pathogens, taking swab samples of chopping boards used for celery, pepper, onions and garlic, recording the sequential temperatures of water used for heating the stuffed intestine and the internal temperature of the stuffed intestine. A general build up of aerobic mesophilic bacteria was observed on addition of various ingredients like spices, celery, pepper, onions, garlic, fat, bread and blood before stuffing the intestine with a semi-solid mixture. The mean total aerobic plate count was 8.8×10⁸±2.7×10⁹and 8.5×10⁵±1.3×10⁶g⁻¹for pre-heated and post-heated stuffed intestine, respectively. Preheated samples yieldedEscherichia coli(89.0%),Staphylococcus aureus(99.0%) andSalmonella(14.6%). The mean temperatures of water used in heat processing ranged from 81.0±3.5 to 87.0±8.0°C, the mean internal temperature of stuffed intestine during processing ranged from 63.2±2.8 to 72.6±2.5°C and the mean processing time ranged from 17.3±10.2 to 26.7±4.2min between processors. The temperature treatments employed by the processors were lower than the 85°C for 10–15min recommended for the product. Consequently, the temperature exposure achieved between a 1–4log decrease in the counts aerobic mesophilic bacteria per gram. Of the 22 ready-to-consume black pudding samples tested, 15 (68.2%), 19 (86.4%) and 3 (13.6%) were positive forE. coli,S. aureusandSalmonella, respectively. Hazards were primarily associated with the keeping of blood at ambient temperature for several hours before use, insanitary practices and keeping processed black pudding at ambient temperature. Critical control points were cooking or heat processing, handling of the product after cooking and holding processed black pudding.