Cut Kernels Research Articles

First Report of Nut Rot Caused by Neofusicoccum parvum on Hazelnut (Corylus avellana) in Italy.

Hazelnut (Corylus avellana L.), which is native to Europe and Western Asia, is a widely distributed and economically important crop in Italy, cultivated on 82,104 ha and its production is 110,618 t (ISTAT 2021). A total of one hundred and eleven black rotted nuts (incidence: 41%) with sunken lesions from Lu and Cuccaro (45°00'21.8"N/8°28'59.6"E), north-western Italy, were collected during the ripening stage of hazelnuts during October-December 2020. Symptomatic half cut kernels were sterilized in 1% NaClO for 1 min, washed in sterile water twice, and dried on sterile filter paper. The fragments were placed onto potato dextrose agar (PDA) containing streptomycin. After 48 to 72 h of incubation at 25°C, fast-growing white colonies with abundant aerial mycelia were observed. On the opposite side of the plates, colonies were initially white, then turned to dark-grayish olive after one week of incubation. Dark colonies produced globose, hyaline, ellipsoidal, unicellular conidia ranging from 12.23-15 μm x 5-6.71 μm. Morphologically, the causal agent was identified as Neofusicoccum parvum (Pennycook & Samuels) Crous, Slippers & A.J.L. Phillips (Crous et al. 2006; Zhang et al. 2021). The DNA from the isolates HMa-19-2 and Hwb-4b-2 was extracted with the E.Z.N.A. Fungal DNA mini kit (Omega Bio-tek) according to manufacturer instructions. Molecular identification was confirmed by sequencing of rDNA internal transcribed spacer (ITS) using primers ITS1/ITS4 (White et al. 1990) and translation elongation factor 1-alpha (tef-1α) gene by using the primers EF1-728F/EF1-986R (Carbone & Kohn, 1999). The sequences of both isolates were deposited in GenBank for ITS (accession numbers MZ848132 and MZ848133) and for tef-1α gene (accession numbers MZ913266 and MZ913267). The BLAST analysis showed 99% identity with ex-type strain of N. parvum (CMW9081) for ITS and tef-1α. Maximum likelihood method based on combined sequences of ITS and tef-1α genes was performed and the isolates of N. parvum clustered with ex-type strain of N. parvum (CMW9081; eXtra file). Pathogenicity of both isolates were tested on ripening hazelnuts (BBCH: 85) to evaluate Koch's postulates. Three nuts per isolate, and per three replicates, were surface disinfected with 1% NaClO. A piece of shell (5 mm diameter) from nuts was removed with a sterile cork borer, then nuts were inoculated with PDA mycelium plugs of the same diameter cut from 7 days old PDA colony (Seddaiu et al. 2021). The control nuts were treated with sterilized PDA plugs. All inoculated nuts produced black lesions with softening pulp (eXtra file). Additionally, abundant white-gray mycelium developed on the inoculation sites. Control nuts showed no symptoms. Neofusicoccum parvuwas recently reported in Italy on chestnut (Seddaiu et al. 2021) and blueberry (Guarnaccia et al. 2021). The fungal pathogen was also reported as agent of grey necrosis of hazelnut in Chile (Duran et al. 2020). However, this is the first report of N. parvum on hazelnut nut in Italy. The findings suggest that N. parvum could severely affect hazelnut production in Italy. Accurate identification of the pathogen will support the growers to manage the disease.

Influence of sweet corn harvest date on kernels quality

Sweet corn has a very short period of optimum harvest maturity, and its quality changes rapidly close to and following the peak. The aim of this study was to determine the sweet corn quality on the ground of some physicochemical properties of intact kernels (moisture content, compression, shear and puncture force, bulk density, sugar and starch contents) and cut kernels (processing recovery, cut corn yield) at four subsequent harvest dates. The moisture content, sugars level, and ear yield decreased. The starch level, bulk density (intact and cut kernels), compression force, shear force and puncture force, processing recovery and cut corn yield increased. The first harvest date showed a greater advantage in the higher sweet corn quality for processing than the following harvest date. The moisture decreased from 77.41% to 69.83% with delayed harvest date. A decline was observed of sweet corn quality (increase of force in compression, shear and puncture tests, raise in the starch level). However, the following harvest date had an advantage in a higher processing recovery and cut corn yield.

Evaluation of Quantitative and Qualitative Losses of the Cutting Process for Sweet Corn Kernels

Sweet corn kernels for the food processing industry are mechanically removed from the cob. This mechanical process causes large quantitative and qualitative losses. The goal of this research was to determine the effect of cutter head speed on kernel losses, kernels of inferior quality, and sugars losses during the process of the cutting the kernel off the cob. The quantitative and qualitative sweet corn kernel losses were determined at three angular speeds of the corn cutter head: 167.5, 230.4, 293.2 rad/s with three standard sweet corn varieties (su-1): Boston, Jubilee, and Spirit. The kernel losses were determined as the percentage of the mass of kernels left on the cob core after removal. The condition of the cut kernel section was used as the index of the quality of kernel cut-off. The quality of cutting was estimated to be good if the cutting surface was smooth and no mass losses were observed. When the cutting surface was ragged or if mass loses were observed this indicated kernels of inferior quality. The data obtained confirmed statistically the effect of increasing cutter head speeds from 167.5 to 293.2 rad/s on the quantity and quality of cut kernels. The studies showed that kernel losses decreased from 51% to 27%, the number of kernels of inferior quality decreased from 64% to 44% and sugar losses from 48% to 33%. The cut kernel yield increased from 29% to 52%.

BROWNING OF FRESH-CUT SWEET CORN KERNELS AFTER COOKING IS PREVENTED BY CONTROLLED ATMOSPHERE STORAGE

Reduced O2 plus elevated CO2 (2% O2 + 10% CO2) was very beneficial in maintaining the visual quality of fresh-cut sweet corn kernels and reduced sugar and flavor losses during 10 days storage at 5 °C compared with storage in air. The main benefit of this controlled atmosphere (CA) was to prevent after cooking browning. Preliminary results indicate that after cooking browning is not associated with a Maillard reaction since 5-hydroxymethylfurfural (HMF), the characteristic intermediate compound produced during the Maillard reaction, is not present in cooked sweet corn kernels exhibiting browning. There were no significant changes in the total soluble phenolics content during storage in air or CA, but the soluble phenolic levels decreased with cooking, which suggests that the after cooking brown color may be due to as yet unidentified insoluble phenolic-protein complexes in the cooked sweet corn tissue The total aerobic microbe count increased with storage and the increase was significantly greater in air. This suggests that the browning could be a response of the sweet corn tissue to the microorganisms, or it may be associated with some product of microbial enzyme activity. INTRODUCTION Fresh-cut sweet corn is a very perishable product since the kernels have a very high respiration rate that increases the rate of deterioration compared to intact sweet corn. Previous work with fresh-cut sweet corn showed that this product can be stored for 10 days in low temperature (0-1 °C). Using atmosphere modification (2% O2 plus 10% CO2) allows storage even at higher temperature (5 °C) without much loss in visual or chemical quality (Brecht, 1999; Riad and Brecht, 2001). There are two main problems associated with this product: loss of sugar and flavor (dimethyl sulfide, the main component of sweet corn aroma), and browning that can occur after cooking when the cut kernels are stored in air at higher than optimum temperatures (Riad and Brecht, 2001). Blanchard et al. (1996) described a similar after cooking browning problem in air-stored diced onion, which was eliminated by storage in 10% CO2. After-cooking browning as a result of the Maillard reaction (a nonenzymatic reaction between sugars and free amino acids usually associated with thermal processing) is common in the food processing industry. This reaction produces 5-hydroxymethylfurfural (HMF) (Bayindirli et al., 1995; Gogus et al., 1998). In the case of sweet corn, the possibility of Maillard reaction would seem to be very high since sweet corn has high levels of free amino acids and sugars (Courter et al., 1988; Grunau and Swiader, 1991), and because the brown color does not develop until the kernels are cooked. Another possibility for this browning is the autooxidation of phenolic compounds that cause polymerization of polyphenolic compounds (Talcott and Howard, 1999). It is well known that phenolic acids increase after wounding (Babic et al., 1993a,b; Howard and Griffin, 1993; Ramamurthy et al., 1992). Brecht (1999) noticed that the browning is severe in cut kernels but there is no browning in intact kernels, which also suggests that the cutting or injured tissues in the kernels might result in elevated levels of phenolics that may play a role in the after cooking browning. Fresh-cut products may have high microbial loads (circa 10 to 10 CFU/g) and these populations may increase during storage and reach high levels (e.g., 10 CFU/g) in Proc. XXVI IHC – Issues and Advances in Postharvest Hort.

Evaluation of Color Characteristics of Cross-Sectioned Wheat Kernels

The color of wheat flour is an important commercial factor and improvement of the color characteristics of kernels is one of the breeding objectives in Japan. Methods were developed to measure color characteristics of both wheat kernels and wheat flour. Wheat kernels were fixed on a newly developed holder with light-curing resin, and a smooth cut-surface was prepared by a programmed cutting of a diamond wheel. Binder-free wheat flour was formed into cylindrical pellets to remove trapped air by repeated compression with a hydraulic press machine. Cut kernels and flour pellets were moistened and analyzed by a two-dimensional colorimetric method. Color changes of both specimens were stabilized after 3 h of moistening. And a comparison of their colorimetric results revealed the possibility of evaluating wheat flour color without milling the kernels. This is useful as an early generation selection method of breeding of wheat because the dissected embryo side retains the germination ability.

Aflatoxin Production among Almond Genotypes Is Not Related to Either Kernel Oil Composition or Aspergillus flavus Growth Rate

Genetic differences were observed in levels of aflatoxin production following controlled inoculations of California almonds [Prunus dulcis (Mill.) D.A. Webb, syn. P. amygdalus, Batsch.; P. communis (L.) Arcangeli, non Huds.]. Genetic variation was also observed in kernel oil composition, and in susceptibility to Aspergillus flavus Speare as indicated by rate of mold expansion on the surface of cut kernels. Several almond lines resulting from the introgression of peach [P. persica (L.) Batsch] germplasm had very low aflatoxin levels relative to commercial cultivars tested. Peach-derived almond breeding lines and cultivars also produced some of the highest oil quality as determined by the proportion of oleic acid, and by the oleic to linoleic acid balance. The proportion of linoleic acid to total oil ranged from 16% to almost 30%. No correlations were detected between aflatoxin production in inoculated almond kernels and either kernel oil composition or mold growth rate on injured kernel tissue.

Feeding and Mortality of Sitophilus granarius (L.) Adults During Simulated Winter Farm Bin Temperatures 1

After gradual cold-temperature acclimation, granary weevils, Sitophilus granarius (L.) (Coleoptera: Curculionidae), fed on cut wheat kernels, but not on undamaged kernels, at 4.4°C. Mortality was greater for weevils confined with single, uncut kernels than for those confined with cut kernels, and males died sooner than females.

Influence of Insecticides on Sweet Corn Quality and their Effectiveness in Control of Corn Earworm1

Abstract Six insecticides (methomyl, permethrin, dicarbosulf, fenvalerate, fluvalinate, UBI-W439) were evaluated for their effect on quality of fresh cut kernels of sweet corn (Zea mays L.) and control of corn earworm, Heliothis zea (Boddie), Lepidoptera: Noctuidae. Corn color, moisture, and soluble solids were unaffected by any of the insecticides, and all, except UBI-W439, provided acceptable earworm control.

FLAVOR AND TEXTURE OF PRESERVED INTACT SWEET CORN: COMPARISON WITH CUT SWEET CORN AND STORAGE TESTS

ABSTRACTSensory studies were conducted to determine if intact or unit kernels of sweet corn (i.e. kernels which are detached at their normal abscission layer and lack a cut surface) can replace cut kernels. Samples of intact or unit kernel sweet corn were compared hedonic‐ally and by relative preference with samples of cut sweet corn after appropriate processing. Stability of the frozen and canned intact kernels was studied for one year. Hedonic ratings for frozen intact corn yielded values of 7.4–7.6 and compared to values of 6.0–6.2 for cut corn. Hedonic ratings for canned intact corn yielded values from 6.4–6.8 and compared to values of 5.9–6.1 for cut corn. Laboratory taste panels expressed preference for intact samples in 86–89s of the judgements of frozen corn and in 64–86s of the judgements of canned corn. Both flavor and texture of the intact corn were most frequently cited as the reasons for preference. Frozen samples of intact kernels were stable for at least 1 yr at −18°C. Canned samples of intact kernels of Golden Jubilee and Golden Happiness were stable for 1 yr at 18°C. Sensory differences were detected in Stylepak samples at the 12‐month evaluation.

IDENTIFICATION AND MEASUREMENT OF THE RESISTANCES TO ABSCISSION OF INTACT OR UNIT KERNELS OF SWEET CORN

ABSTRACTThe successful detachment of sweet corn kernels as intact kernels promises large yield and effluent advantages over cut kernels during processing but requires a low strength of kernel attachment to the cob. This work describes the development of a test method for measuring the strength of kernel attachment and applies it to the identification of %varietal differences. Two components resisting detachment were identified: a base or abscission component and a side or frictional component. Base components as low as 1.3 Newton (N) (Golden Happiness) and as high as 5.5N (Illini Xtra Sweet) and side components as low as 1.3N (Vanguard) and as high as 4.0N (Golden Happiness) were observed. Abscission strength was found to correlate with prototype machine processing variables such as kernel mass production rates and the completeness of kernel removal from the cob.