COMPARISON OF PHYSICAL METHODS FOR ESTIMATING THE MATURITY OF RAW, FROZEN AND COOKED PEAS

The back extrusion cell, Maturometer, Kramer shear press, FMC Tenderometer, and Ottawa Texture Measuring System wire extrusion cell gave useful estimates of the maturity of raw peas but, two viscosity methods gave unsatisfactory estimates. None of the instruments gave useful estimates of maturity of frozen peas that had been thawed or cooked because blanching conditions and the rate of freezing of the peas affected the readings. The most reliable estimate of raw pea maturity from thawed frozen peas was the alcohol insoluble solids content.     

Suitability of the Ottawa Pea Tenderometer to assess the quality of raw peas

This paper gives an account of the relationship obtained between the force readings for samples of peas using the Martin Pea Tenderometer, the Ottawa Pea Tenderometer and the Instron 1140 used with an Ottawa Pea Tenderometer food cell, together with sensory quality of canned and frozen peas and alcohol insoluble solids. The effect of temperature on the readings obtained for the different instruments, and the effect of interchangeability of Ottawa Pea Tenderometer cells and components are also reported together with information concerning the influence of bruising and damage to a sample of peas.     

Quality and Maturity Indices for Postharvest Handling of Southern peas

Purple hull pinkeye southern peas were harvested at three levels of maturity, shelled and stored at three temperatures (1, 5, and 20°C). Samples were evaluated at three storage intervals (1, 4 and 7 days) using 11 different indicators of quality. Alcohol insoluble solids and total solids measurements were most closely related to maturity differences. Derived instrumental color functions (AH and AE), pH, total acidity, and % green peas were the quality indices providing the best separation of the effects of maturity and storage. Instrumental color values were more ciosely correlated to changes in % green peas than total chlorophyll concentration. The proposed indices provide the means for a unified study of quality changes in sourthern peas during all stages of postharvest handling.     

Prediction of sensory quality by near infrared reflectance analysis of frozen and freeze dried green peas (Pisum sativum)

Frozen, green peas (Pisum sativum L ) of different varieties and different levels of maturity were evaluated by sensory analysis using a panel of ten trained judges. Two texture variables (hardness and mealiness) and four flavour variables (pea flavour, sweetness, fruity flavour, off flavour) were considered. Near infiared reflectance ( N I R ) analysis was performed with the same material, on both the fiozen and fieeze dried peas. The N I R instrument was calibrated to predict the sensory variables using the multivariate analytical method of principal component regression. Tenderometer readings of the same peas were also calibrated to predict the sensory variables. N I R analysis on the fieeze dried peas showed relative ability of prediction (RAP) values for the sensory variables which were higher than those for the tenderometer readings. The sensory attributes pea flavour and hardness were predicted with higher RAP values by tenderometer readings than by N I R analysis on fiozen peas. For the rest of the attributes, N I R analysis on fiozen peas gave higher RAP values than tenderometer readings. N I R generally gave high RAP values, and this tentative study suggests that N I R analysis could be a useful tool in instrumentally assessing the quality of frozen peas.     

The relationship between maturity and quality of canned broad beans (Vicia faba L.)

Summary. This paper describes a co-operative investigation carried out by the Fruit and Vegetable Preservation Research Association and eight of its member firms to determine optimum maturity of broad beans for canning.
The results indicate that (a) there was no difference in flavour in canned broad beans harvested at tenderometer readings from 90 to 200, (b) there was a significant linear deterioration in texture as beans matured, (c) alcohol insoluble solids of raw and canned beans increased linearly as beans matured, (d) a linear relationship was found between tenderometer readings and sample size, (e) consumers equally preferred canned broad beans harvested at tenderometer readings of 120 and 160 and (f) optimum maturity of broad beans for canning from the data obtained was at a tenderometer reading of 136 using a 5 oz sample of raw beans.     

Constitution of leguminous seeds: VII.—Ease of cooking field peas (Pisum sativum L.) in relation to phytic acid content and calcium diffusion

Cooking tests (single pea puncture), phytic acid analyses, water absorption and ⁴⁵Ca diffusion experiments have been performed on individual peas selected from two samples of field peas (Pisum sativum L.). One sample (Avion brand) was judged by the supplier to have good cooking qualities and the other sample (3CW brand to have poor cooking qualities. The rapid rate of cooking of the interior of the pea, compared with that of the periphaeral region was not associated with a higher phytic acid content. There was no consistent difference between the distribution of ⁴⁵Ca in Avion and 3CW peas that had been soaked in water containing ⁴⁵Ca. There was a significant (1 % level) difference between the average loss of solids of Avion and 3CW peas that had been soaked at 25°. Pea plants were injected with ⁴⁵Ca ind the peas were harvested. Autoradiograms of the radioactive peas demonstrated the movement of calcium in the seed coats and in the cotyledons during cooking.     

Constitution of leguminous seeds VI.—The cookability of field peas (pisum sativum l)

Cookability tests (single pea puncture) and phytic acid and calcium analyses have been performed on individual peas selected from two samples of field peas (Pisum sotivum). One sample (Avion brand) was judged by the supplier to have good cooking and the other sample (3CW brand) to have poor cooking qualities. There was a significant correlation between the cookability of individual peas (seed coats removed) and their phytic acid content when the peas were cooked in distilled water. There was no such correlation between cookability and calcium content, but there was a correlation between cookability and the ratio of the calcium contents to the phytic acid contents of the peas. The difference between the average cookability of Avion peas and 3CW peas in water containing calcium does not appear to be related to differences in the average phytic acid or calcium contents of the two samples.     

ALCOHOL-INSOLUBLE CONSTITUENTS OF JUICE VESICLES OF CITRUS FRUIT

SUMMARY– The texture of the edible portion of citrus fruit is determined by the characteristics of the juice vesicles and their insoluble constituents. Alcohol-insoluble solids (AIS) of the juice vesicles of several varieties of oranges, grapefruit and tangerines were studied at different stages of maturity. The protein content of the AIS as determined by the Kjeldahl method was found to decrease with fruit maturity, although total amount per fruit tended to increase. Polysaccharides were separated by extracting the AIS with alkali of various concentrations. Each fraction after hydrolysis was analyzed for the monomers both by paper chromatography and gas chromatography of the silylated derivatives. Galactose, arabinose and traces of glucose were found in fractions associated with galacturonic acid, and xylose, arabinose and glucose in different proportions were found in the hemicellulose and cellulose fractions. Traces of rhamnose and other uronic acids also were detected.     

Instrumental measurement of pomegranate texture during four maturity stages

Texture of pomegranate fruit and arils are the main quality attributes in the food process industries. In this study, the texture properties of pomegranate fruit and arils (cv. “Ashraf”) at four different stage of maturity (88, 109, 124, and 143 days after full bloom) were evaluated using the puncture test (rupture force and rupture energy) and compression test (bioyield force, rupture energy, and young modulus). The tests showed that all studied textural parameters were sensitive textural parameters for distinguishing the maturity stages. Rupture force and rupture energy of pomegranate fruit were determined at top, middle, and bottom positions of the fruit. The results showed that compression load values of aril increased with advances in maturity stage of fruit, while puncture load values of fruit decreased. The textural properties of pomegranate fruit and arils exhibited a strong dependence (p < .05) on the degree of maturity at harvesting time. Also results showed that rupture force of three different studied positions of fruit was severely different. The highest and lowest values were observed at top and middle position, respectively.     

MEASUREMENT OF PEA TENDERNESS IV. Development and Evaluation of the Test Cell*

A wire extrusion cell was developed to measure pea tenderness. The area of the cell and the wire grid dimensions affected the readings. The maximum force was linearly related to the total length of the shearing wires and the open area of the grid. Cells could be made interchangeable in testing unsieved peas within 1% or better using economic manufacturing tolerances. Sample temperature, time after harvest and damage to the wires of the test cell had negligible effects on the readings. The effect of variation in compression speed was small and erratic. Sample weight, however, had a marked effect on the results.     

EVALUATION OF TOMATO QUALITY DURING STORAGE BY ACOUSTIC IMPULSE RESPONSE

The aim of this research was to evaluate the ability of acoustic impulse response to monitor "Heatwave" tomato quality during storage. The tomato was excited and the response signal is captured using the film sensors. The results showed that acoustic impulse response parameters (dominant frequency, firmness index and elasticity coefficient) of "Heatwave" tomato decreased with storage time. The dominant frequency, firmness index and elasticity coefficient had no correlation with soluble solids contents or pH, but had a good correlation with compression force and puncture force. There was a better correlation between elasticity coefficient and compression force (or puncture force); hence, elasticity coefficient could be a better index of "Heatwave" tomato firmness. The acoustic impulse response is a potential factor in order to determine the firmness of "Heatwave" tomato.

PRACTICAL APPLICATIONS

Tomato firmness is an important characteristic because firmness of tomato flesh influences the mouth sensory feel. This results showed that acoustic impulse response parameters (dominant frequency, firmness index and elasticity coefficient) of "Heatwave" tomato decreased with storage time. The dominant frequency, firmness index and elasticity coefficient had not correlation with soluble solids contents or pH, but had a good correlation with compression force and puncture force. There were better correlation between elasticity coefficient and compression force (or puncture force), and hence elasticity coefficient could be a better index of "Heatwave" tomato firmness. The acoustic impulse response is potential to determine the firmness of "Heatwave" tomato.     

Pectin Methyl Esterase Activity in Southern Peas (Vigna sinensis)

SUMMARY: Pectin methyl esterase (PME) activity was investigated in vitro in Southern peas (Vigna sinensis). Experiments were conducted to determine the effect of NaCl concentration, pH, temperature, maturity, frozen storage and rinsing the peas on PME activity.
The optimum salt level for maximum PME activity in the Purple Hull Pink Eye (PHPE) and Princess Ann (PA) varieties was ascertained to be 0.25 M. The pH optima were: PHPE, 8.5; and PA, 7.5 to 8. The remaining studies were made using peas of the PHPE variety which were harvested at 3 stages of maturity. Maximum enzymatic activity occurred at 50°–60°C. Partial inactivation occurred at 65°C. The mean Q₁₀ was 1.35 over the range of 30°–50°C.
PME activity was dependent upon the maturity of the peas. The most immature peas had an activity level about 2.5 times that found in the most mature peas. Peas subjected to frozen storage had a higher activity than the fresh peas; the increased activity was more pronounced in the more mature peas.
Rinsing the peas removed significant amounts of the enzyme. A greater proportion of PME was removed from the more immature peas than from the more mature ones. With the immature, frozen peas PME activity was reduced 22.7% by rinsing; whereas, in the fresh counterpart the reduction was 11.1%. The rinse water from frozen peas contained more PME activity than did rinse water from fresh peas. Also, the activity in rinse water from the most immature peas was about 2.7 times that from the most mature ones. Upon standing, PME activity in the slurries prepared from frozen peas continued to increase up to 3–4 hr.     

A NONDESTRUCTIVE TEST FOR DETERMINATION OF OPTIMUM MATURITY OF FRENCH (GREEN) BEANS (Phaseolus vulgaris)1

Optimal maturity stage of Burpee Stringless Variety of French (green) beans was determined by a trained sensory panel using beans harvested at definite intervals of growth till over-maturity. Of the changes in ten physico-chemical characteristics studied during growth, weight to length (W/L) ratio is closely related to the sensory characteristics and can be used as a simple non-destructive test for determining the optimal maturity. The beans are very tender up to a W/L ratio of 0.4 g/cm, tender from 0.41 to 0.5 g/cm which is optimal mature stage, mature from 0.51 to 0.6 g/cm, and over-mature thereafter. The maximum force required to cut the bean by placing on its edge or flat in the triangular slot of the Warner-Bratzler shear press was 9.0 kg in tender beans and could be made use of as an instrumental method for determining the maturity. The force required to cut the beans edgewise was more than in the flat position at or before the optimal maturity and the values reversed thereafter. Changes in total solids, alcohol insoluble solids and fibrous matter contents between tender and mature ones are too sudden and large during the short transition period for being used as objective method(s) but yielded meaningful data when considered along with W/L ratio or shear force.     

Evaluation of tomato textural mechanical properties

The texture of fresh tomatoes (Lycopersicum esculentum Mill., ‘Momotaro’) at three different stage of ripeness (mature green, pink, and red) was intensively evaluated. The double-cycle load plate compression test showed that initial firmness, average firmness, energy absorption, deformation ratio, and relaxation ratio were sensitive textural parameters for identifying the maturity stages. From a puncture test, initial firmness, average firmness, apparent modulus of elasticity, rupture force, toughness, and deformation at the rupture point were sensitive to the maturity stages. The mature unripe tomato deformed linearly as a function of force; hence, the firmness was constant. However, the fully ripe tomato firmness increased as a function of applied force. The fruit strain increased during ripening, and it was independent of fruit size. The unripe tomato was more elastic than the ripe one. The peel at the mature green stage contributed approximately 70% of the firmness of the fruit and approximately 90% at the pink stage and red stage. The rupture force by the puncture test (traditionally, peak force) was correlated well with other textural parameters, which indicated that it could be used as a firmness representative parameter, as has been used by many researchers. The degree of elasticity was a better indicator for elasticity than the relaxation ratio.     

Measurement of the spreadability of margarine and butter using a single pin maturometer

Single pin maturometer (SPM) readings were taken on samples of margarine and butter having temperatures in the range 0–25°C. The spreadability of the same samples at the same temperatures was also assessed by a panel of twenty adults using an hedonic scoring scale. The SPM readings and scores for spreadability varied markedly with the type of product and its temperature. The temperature corresponding to maximum scores for spreadability for a hard margarine and butter was about 20°C and for a soft butter was about 15°C. A soft margarine received scores of more than 6(= very good) on the 7 point hedonic scale over the temperature range 0–10°C and the data indicated that spreadability may also be 'very good' at temperatures just below 0°C. The SPM reading corresponding to the maximum score for spreadability was about 100 g for all samples. The SPM was shown to be suitable for the routine assessment of the spreadability of margarine and butter.     

Nondestructive estimation of maturity and textural properties on tomato ‘Momotaro’ by near infrared spectroscopy

Near infrared spectroscopy offers the possibility to classify and predict the internal quality of fruits and vegetables. The objective of this study was to evaluate the ability of near infrared spectroscopy to classify the maturity level and to predict textural properties of tomatoes variety “Momotaro”. Principal component analysis (PCA) and Soft independent modeling of class analogy (SIMCA) were used to distinguish among different maturities (mature green, pink and red). Partial least squares (PLS) regression was used to estimate textural properties, alcohol insoluble solids and soluble solids content of the tomatoes. The PCA calibration model with mean normalization pretreatment spectra of mature green tomatoes, gave the highest distinguishability (96.85%). It could classify 100.00% of red and pink tomatoes. The SIMCA model could not give better accuracy in maturity classification than individual PCA models. Among the textural parameters measured, the bioyield force from the puncture test with the near infrared (NIR) spectra (between 1100 and 1800 nm) pretreated by multiplicative scatter correction (MSC) had the highest correlation coefficient between NIR predicted and reference values (r = 0.95) and lowest standard error of prediction (SEP = 0.35 N) and bias of 0.19 N. The ratio of standard deviation of reference data of prediction set to standard error of prediction (RPD) was 2.71. In the case of Momotaro tomato, NIR spectroscopy by using PLS regression could not predict alcohol insoluble solids in fresh weight accurately but could predict soluble solids content well with r of 0.80, SEP of 0.210 %Brix and bias of 0.022 %Brix.     

An Evaluation of Marinated Southern Peas (Vigna unguiculata)

Cooked southern peas (Vigna unguiculata) of two levels of maturities were soaked in sweet- or hot-flavored marinades. Marinade treatments and maturity level of the peas affected most attributes tested. Treated peas had less moisture, protein and nitrogen-free extract and more fat, crude fiber, ash and caloric content than unmarinated peas. Luminosity was reduced, redness was varied and yellowness was increased by marinating. Firmness of marinated peas was increased. PER was not affected and averaged 1.83. pH was lowered from 6.6 to 3.9; acidity was raised from 0.1% to 1.9%. Neither treatment nor maturity affected the microbiological counts. Samples were scored as “like slightly.”     

A Puncture Testing Method for Monitoring Solid Substrate Fermentation

Meitauza, an indigenous Chinese food made from fermented okara (soymilk residue), was used as a model system for monitoring solid substrate fermentations. The Instron Universal Testing machine and Chatillon hand operated force gauge were used to measure the force to penetrate meitauza as an estimation of mycelial binding. Increased firmness during fermentation was caused by fungal growth and not by water loss and surface crusting. Puncture force readings with the Instron were werll correlated (r = 0.86) with Chatillon measurements. The results of this study indicate that textural measurements using puncture force may have valuable application in monitoring the degree of mycelial growth or fermentation in a solid substrate.     

Ein Beitrag zur Biosynthese amylosereicher Erbsenstärken

Contribution to the Biosynthesis of High-amylose Pea Starches Biosynthesis of starch is a complex process but few details are still unknown. This paper describes an investigation upon pea starch biosynthesis. Peas as a source of starch offer two qualities, a pea starch with 40% amylose content (smooth pea starch) and a pea starch with more than 60% amylose content (wrinkled pea starch). Samples for analysis were taken during growth. According to the quantitative determination of starch and amylose the accuracy of amylose detection was tested. Furthermore a qualitative analysis was carried out by molecular weight estimation of the starch. Both kinds of peas showed a high amylose synthesis during the last few days of growth, whereas amylopectin synthesis was highly in earlier stages. Wrinkled peas have shown only little synthesis activity of amylopectin during maturity. Therefore the amylose content of these peas was higher, instead of equal amylose synthesis quotas of both smooth and wrinkled peas.