Food Processing and Preservation

Common spectrometric methods to determine
hydrogen peroxide scavenging activity require time-consuming
extraction protocols and become poorly reliable
because of the sample turbidity or the presence of UV-absorbing
compounds. The present work suggests the use of
reaction calorimetry to determine the antioxidant capacity of
fruit juices, fruit puree, tea, coffee and alcoholic beverages,
like wines. This experimental approach that does not imply
the above drawbacks and does not require any extraction
protocol allows the direct monitoring of the reaction between
food beverages and H2O2. The overall exothermic effect
reflects the extent of the scavenging activity of the samples
versus hydrogen peroxide. The reliability of the approach is
assessed through the study of the reaction between hydrogen
peroxide and ascorbic acid at different concentration and pH
at room temperature.

Various aromatic rice varieties such as Kalizira, Begun Bichi, BRRI dhan-34, BRRI dhan-37, BRRI dhan-50, Philipine Katari were analyzed for physiochemical, total phenol, flavonoid contents and functional properties. All aromatic rice varieties had moisture contents (11.25 to 15.13%), protein (3.23 to 6.21%), fat (0.68 to 1.45%) and ash (0.88 to 1.46%). The maximum amount of amylose and starch content were obtained in BRRI dhan-37 and BRRI dhan-50 (23.01 and 72.606%, respectively). Total phenolic content was higher in BRRI-37 (474 mg/100 g); whereas, lower value was observed in BRRI dhan-34 (268.67 mg/100 g) variety. Both Philipine Katari and kalizira variety possessed highest level of flavonoid content among all rice varieties. Highest water absorption index value was found in BRRI dhan-37 and lowest in Begun Bichi variety. On the other hand, water soluble index value was varied by 1.32 to 2.12% in all aromatic rice varieties. Therefore, the study indicates that aromatic rice could be used as functional food ingredients as well as sources of natural phytochemicals.

An attempt was undertaken to investigate the effect of various common processing treatments, such as (a) without pedicle and cut longitudinally plus treated with 0.01% potassium metabisulphite (KMS), (b) without pedicle and sliced, (c) without pedicle as a whole, and (d) as a normal whole green chilli with pedicle, on the shelf life during storage in high density polyethylene (HDPE) and low density polyethylene (LDPE) packages at room temperature. The nutritional quality in terms of proximate compositions, Vitamin-C, beta-carotene and mineral contents of green chilli powder were also assessed. The chilli powder from the treatment (a) showed the highest stability up to 195 days in the HDPE pouches. In relation to proximate compositions and mineral contents, the processing treatments had a significant effect on them, except for Vitamin-C content at P<.0001. The results showed that the nutritional quality in all the samples of green chilli powder was better than that of the red chilli powder. Vitamin C content was reduced around 50% in all the samples due to the processing, while beta-carotene content was significantly increased as compared to the fresh green chilli. A simple calculation revealed the potential of green chilli powder as a value added and alternative spice.

Bio-Fresh tm edible coatings in four concentrations (0.5, 0.8, 1.0 and 1.2%) were investigated on quality characteristics of conference pears (Pyrus communis L. cv. Conference) with regards to its permeability. The Bio-Fresh TM was applied on pears by dipping. It was found that the effect of Bio-Fresh TM on pears was significantly effective in maintaining the skin color of green and only coating 1.2% Bio-Fresh TM delayed the changes of firmness, soluble solid content and retardation of shriveling and weight loss. Coating of 1.2% Bio-Fresh TM showed low permeability to respiratory gases (O 2 and CO 2) and created modified atmosphere, reduced decay and improved the quality of pears. Increasing concentration of coating on the surface skin of pears blocked the pores and lenticels, providing a drop-down in O 2 partial pressure. As a consequence, coating of 1.2% showed low permeability with good quality of pears. The results of this study suggest that coating of 1.2% Bio-Fresh TM increased shelf life of pears after 30 days without significant losses in quality.

The study attempts to determine the period of acceptability of cooked rice (parboiled) of Pajam variety. Cooling studies on cooked rice showed the highest cooling rate in soaked water, and successively followed by refrigeration, under fan air and at room temperature (30±2 0 C). The moisture, protein, fat, ash and total carbohydrate contents (wb) were 9.68, 4.93, 0.36, 0.32 and 84.71 % respectively in raw rice; 12.37, 8.36, 0.40, 0.57 and 78.29 % respectively in parboiled rice and 65.99, 3.24, 0.15, 0.14 and 30.47 % respectively in cooked rice (parboiled). After 24 hours of storage moisture, protein, fat, ash and carbohydrate contents were 66.47%, 5.69%, 0.13%, 0.14% and 15.73% respectively in rice at room temperature; 69.12 %, 3.64 %, 0.13 %, 0.13 % and 26.98 % respectively in refrigerated rice and 64.38 %, 3.53 %, 0.15 %, 0.15% and 31.78 % respectively in frozen rice. The cooked rice stored at room temperature for 24 hours showed 4.2x10 4 cfu/g, and the refrigerated and frozen rice showed no viable load while after another 24 hours of storage the refrigerated rice showed 6.9x10 5 cfu/g and frozen rice showed no load. The sensory evaluation revealed the 'cooked rice' and 'refrigerated and reheated rice' were equally acceptable and ranked as 'like very much' in terms of colour, taste, texture and overall acceptability. To ensure the maximum hygienic quality and desirable taste the cooked rice (parboiled) might be kept for a maximum period of 20 hours at room temperature and 48 hours in a refrigerator and reheated by microwave oven for 1 minute before serving to the consumer.

An attempt was taken to select the effective peeling methods of potatoes based on mineral content and to formulate biscuits using potato flour as a partial substitute of wheat flour. The potatoes were collected and washed with water thoroughly to remove adhered dirt and soil. Fresh potatoes (P 1), potatoes peeled before boiling (P 2) and potatoes peeled after boiling (P 3) were analyzed for mineral content. Significant (p<0.05) effect of peeling treatment on mineral content was observed in this study. However, potato with peel was scored with highest mineral content namely Calcium (9.40mg/100g), Magnesium (21.6mg/100g), Potassium (413.91mg/100g), Phosphorus (60.57mg/100g), Iron (0.78µg/100g) and Zinc (0.29µg/100g) among samples. On the basis of mineral content, potato with peel was selected to produce potato flour to replace wheat flour partially in preparing nutritionally enriched biscuit. Potato flour was blended with wheat flour in ratio of 3:17, 1:3 and 7:13 in preparation of biscuits with maintaining all other ingredients constant. The prepared biscuits were evaluated for sensory quality by Hedonic Rating Test. The sensory evaluation revealed that the biscuits prepared using 25 percent potato flour were almost equally acceptable as control biscuits and secured the score for overall acceptability (7.20) and ranked as 'like very much'. Biscuits prepared using 35 percent potato flour secured the lowest score (5.20) in term of overall acceptability and was unacceptable to the panelist. To ensure adequate minerals, the use of potato flour to substitute wheat flour up to 25% level is advocated.

During the manufacturing of fresh-cut apples, a number of biochemical events, overall exothermic, contribute to increasing the reaction rate of the fruit and the browning of its wounded surface. This work applied isothermal microcalorimetry to compare the overall effect of such complex events before and after treatments with ascorbic acid solutions, pulsed lights or UV-C lights. Briefly, apple samples were cut into cylinders and dipped in solutions containing ascorbic acid (0–2.5%) or exposed to high energy doses of light (from 6 to 175 kJ/m2). In general, the heat-flow signal recorded by microcalorimetry was inversely proportional to the intensity of the applied treatment. In case of treatments with ascorbic acid, the heat-flow signal was empirically deconvoluted in three distinctive signals, respectively, (I) an exponential decay, (II) a gaussian central curve and (III) a final logistical function. The first and the third functions were constant regardless of the concentration of ascorbic acid used. Only the second Gaussian function was correlated with the concentration of ascorbic acid and the area was used to evaluate the efficacy of the process. Overall, this work contributes to the understanding of the heat produced by fruit after wounding and, from a practical standpoint, can help compare the effects of different treatments on fresh cut fruits.

A major cause of food oxidation is free-radical generation via the Fenton reaction. Calorimetric measurement of heat rate during the reaction between food antioxidants and H 2 O 2 with added Fe(II), the catalyst in the Fenton reaction, is used to ascertain the reactions occurring and evaluate stoichiometric, thermodynamic and kinetic parameters for the reactions at 25°C. The reaction of ascorbic acid with H 2 O 2 at varying pH and concentrations of ascorbic acid, Fe(II), and H 2 O 2 was used as a model system. Measurements were also made on antioxidants, fruit juices, fruit purees, tea, and coffee. Enthalpies of formation of ascorbate monoanion (-1124 ± 3 kJ/mol) and dehydroascorbate anion (-1069 ± 2 kJ/mol) are estimated from literature data and Thornton's Rule to give Δ r H = −325 kJ/mol for H 2 O 2 (aq) + C 6 H 7 O 6 − (aq) = C 6 H 5 O 6 − (aq) + 2H 2 O(l). The experimental results show an initial very rapid reaction of ascorbate monoanion to dehydroascorbate anion followed by an undefined series of reactions with variable stoichiometry (4 ± 2 H 2 O 2 /ascorbate) that are overall described by first order ki-netics. An empirical linear relation between the maximum heat rate observed and ascorbate concentration was found, but no definitive relation was found between total heat and amount of ascorbate. However, the model directly and rapidly provides stoichiometric, thermodynamic and kinetic properties of the radical scavenging activity of food antioxidants and commercial food products. The total heat measured under specified conditions is related to the radical scavenging capacity of the sample; higher values correspond to higher capacity for radical scavenging and vice versa.

This work determines the radical scavenging activity of antioxidants and berry extracts based on the heat generated during their reaction with hydrogen peroxide, under isothermal condition (25 °C). After addition of H2O2 to a water solution containing antioxidants, an exothermic heat flow appeared. After an initial damping time, the signal decayed exponentially, following a first-order kinetic. Through an iterative fitting routine, both thermodynamic (ΔH) and kinetic (k) information were achieved. Such approach was applied toward relevant food antioxidants, revealing that the fastest reactivity (k) was for tannic acid > gallic acid > caffeic acid > ascorbic acid. Interestingly, k was inversely correlated with ΔH (r = −0.96) and with the DPPH test (r = −0.98). Apparently, strong radical scavengers show faster kinetics and lower ΔH-values, as expected, respectively, from a high reactivity toward peroxyl radical and efficient delocalization capacity. Such approach was finally applied to berry extracts (mixed grape seed and skin; chokeberries; grape seed; goji berries). The resulting ΔH-values were correlated with three indices, namely, total phenol, amperometry, and DPPH test. However, k-values largely deviated from these indices. Such discrepancy was explained considering that none of these indices is a “true” measure of the kinetic of the reaction, but only express an apparent concentration. Conversely, reaction calorimetry provides directly and simultaneously both thermodynamic and kinetic properties of the radical scavenging reactivity of antioxidants or natural extracts.

The influence of drying methods on selected mechanical properties and qualities of MR219 rice variety has been investigated. The results showed significant effects of drying methods on bending strength and head rice yields while the average bending strength of paddy were 28.6-31.8 MPa. The effect of drying methods on apparent modulus of elasticity of rice was not significant (204.5-222.4 MPa). The fracture energy of rice varied significantly under control drying but not with industrial drying methods. Higher temperature in drying by IBD contributed in making the grains tougher, where the effect of FBD temperature was positive toward the development of fracture energy inside rice kernel. IBD at temperature above 40°C resulted in lower bending strength in rice kernels which affected head rice yield. Two stage paddy drying practices with FBD using temperature of 115-125°C as first stage is still acceptable, and inclined bed dryer either as single stage or as second stage after FBD should be operated at temperature of \40°C to maintain head rice yield. The whiteness and milling recovery of rice achieved from different drying methods were comparable.

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An attempt was undertaken to investigate the effect of various common processing treatments, such as (a) without pedicle and cut longitudinally plus treated with 0.01% potassium metabisulphite (KMS),(b) without pedicle and sliced,(c) without pedicle as a whole, and (d) as a normal whole green chilli with pedicle, on the shelf life during storage in high density polyethylene (HDPE) and low density polyethylene (LDPE) packages at room temperature. The nutritional quality in terms of proximate compositions, Vitamin-C, beta- ...

The study attempts to determine the period of acceptability of cooked rice (parboiled) of Pajam variety. Cooling studies on cooked rice showed the highest cooling rate in soaked water, and successively followed by refrigeration, under fan air and at room temperature (30±2°C). The moisture, protein, fat, ash and total carbohydrate contents (wb) were 9.68, 4.93, 0.36, 0.32 and 84.71 % respectively in raw rice; 12.37, 8.36, 0.40, 0.57 and 78.29 % respectively in parboiled rice and 65.99, 3.24, 0.15, 0.14 and 30.47 % respectively in cooked rice (parboiled). After 24 hours of storage moisture, protein, fat, ash and carbohydrate contents were 66.47%, 5.69%, 0.13%, 0.14% and 15.73% respectively in rice at room temperature; 69.12 %, 3.64 %, 0.13 %, 0.13 % and 26.98 % respectively in refrigerated rice and 64.38 %, 3.53 %, 0.15 %, 0.15% and 31.78 % respectively in frozen rice. The cooked rice stored at room temperature for 24 hours showed 4.2x104cfu/g, and the refrigerated and frozen rice sho...

The influence of drying methods on selected mechanical properties and qualities of MR219 rice variety has been investigated. The results showed significant effects of drying methods on bending strength and head rice yields while the average bending strength of paddy were 28.6-31.8 MPa. The effect of drying methods on apparent modulus of elasticity of rice was not significant (204.5-222.4 MPa). The fracture energy of rice varied significantly under control drying but not with industrial drying methods. Higher temperature in drying by IBD contributed in making the grains tougher, where the effect of FBD temperature was positive toward the development of fracture energy inside rice kernel. IBD at temperature above 40°C resulted in lower bending strength in rice kernels which affected head rice yield. Two stage paddy drying practices with FBD using temperature of 115-125°C as first stage is still acceptable, and inclined bed dryer either as single stage or as second stage after FBD should be operated at temperature of \40°C to maintain head rice yield. The whiteness and milling recovery of rice achieved from different drying methods were comparable. Keywords Industrial paddy drying Á Inclined bed drying (IBD) Á Fluidized bed drying (FBD) Á Mechanical properties Á Rice quality

During the manufacturing of fresh-cut apples, a number of biochemical events, overall exothermic, contribute to increasing the reaction rate of the fruit and the browning of its wounded surface. This work applied isothermal microcalorimetry to compare the overall effect of such complex events before and after treatments with ascorbic acid solutions, pulsed lights or UV-C lights. Briefly, apple samples were cut into cylinders and dipped in solutions containing ascorbic acid (0-2.5 %) or exposed to high energy doses of light (from 6 to 175 kJ/m 2). In general, the heat-flow signal recorded by microcalorimetry was inversely proportional to the intensity of the applied treatment. In case of treatments with ascorbic acid, the heat-flow signal was empirically deconvoluted in three distinctive signals, respectively, (I) and exponential decay, (II) a Gaussian central curve and (III) a final logistical function. The first and the third functions were constant regardless of the concentration of ascorbic acid used. Only the second Gaussian function was correlated with the concentration of ascorbic acid and the area was used to evaluate the efficacy of the process. Overall, this work contributes to the understanding of the heat produced by fruit after wounding and, from a practical standpoint, can help compare the effects of different treatments on fresh cut fruits.

Common spectrometric methods to determine hydrogen peroxide scavenging activity require time consuming extraction protocols and become poorly reliable because of the sample turbidity or the presence of UV absorbing compounds. The present work suggests the use of reaction calorimetry (RC) to determine the antioxidant capacity of fruit juices, fruit puree, tea, coffee and alcoholic beverages, like wines. This experimental approach, that does not imply the above drawbacks and does not require any extraction protocol, allows the direct monitoring of the reaction between food beverages and H2O2. The overall exothermic effect reflects the extent of the scavenging activity of the samples versus hydrogen peroxide. The reliability of the approach is assessed through the study of the reaction between hydrogen peroxide and ascorbic acid at different concentration and pH at room temperature.

Cereal industry and its derived products have a large economic and social importance worldwide. Baking industries are extensively using wheat flour to produce various baked products. Therefore, in this investigation it is intended to study and determine proximate, physicochemical, functional properties of six brand of wheat flour in Bangladesh. The entire brand had moisture contents: 9.90-12.48%, protein: 8.67-12.47%, fat: 0.893-1.387% and ash content: 0.387-0.707%. The ACI brand had the highest amount of protein of 12.47% whereas Romoni brand had highest fat of 1.387%, fiber: 0.26%, gluten content: 15.34% and water absorption index of 1.9 g/g as compared to other brands. In addition, sodium and calcium content were higher in ACI brand whereas potassium content was higher in Romoni brand. Results showed that wheat flour from all brand could be used to make various type of baked products.

This study was aimed to investigate the effect of processing techniques on the characteristics of green and red chilli powder. Four samples, such as pretreated green chilli paste (PTGP), pretreated green chilli longitudinal slit (PTGL), pretreated whole red chilli (PTWR) and untreated green chilli paste (UTGP), were prepared and dried at 60°C in a cabinet dryer. The pretreatment was blanching in acetic acid solution and soaking immediately in a combined solution of Na 2 S 2 O 5 and CaCl 2. Pretreated samples took a shorter drying time than the untreated sample in reducing moisture content from 86.31 to 8%. Pretreatment before drying resulted in retaining total chlorophyll (* 86%), phenolic compounds (* 32%), green color, and pungency of chilli. Analysis result indicated that more than 60% retention of b-carotene was found while retention of ascorbic acid was comparable. Conclusively, this research reveals a good nutritional profile in cabinet dried green chilli powder, which may open the scope for commercial production.